Recent itsdavis_ucprc items

2025 Condition Survey of High RAP Pilot Projects on El Dorado 49, San Bernardino 215, and San Joaquin 26

Wed, 17 Jun 2026 00:00:00 +0000

Three pilot projects were constructed using hot mix asphalt (HMA) with higher percentages of recycled asphalt pavement (RAP) (25% to 40%) and recycled asphalt shingles (RAS) used at 0% or 3%. The three projects were paved between 2021 and 2022 on State Route 49 in El Dorado County (ED 49), State Route 215 in San Bernardino County (SBD 215), and State Route 26 in San Joaquin County (SJ 26). Two and a half to three years later, pavement condition surveys were conducted to observe surface distresses. On ED 49, the 3% RAS mix exhibited 6% low-severity wheelpath alligator cracking, often with mild pumping. The other mixes on ED 49 exhibited lower levels of alligator and total cracking. No alligator cracking was observed on SBD 215, which includes a cement-treated base not present in the other pilot projects. On SJ 26, all test sections exhibited some form of cracking, though mostly of low severity. Among the mixes, the 25% RAP/3% RAS mix showed the most alligator cracking on SJ 26...

RAP and RAS in HMA Pilot Project on SJ 26: Material Testing, Observations, and Findings

Tue, 9 Jun 2026 00:00:00 +0000

A pilot project for the inclusion of high percentages of reclaimed asphalt pavement (RAP) and recycled asphalt shingles (RAS) in hot mix asphalt (HMA) was built on State Route 26 in San Joaquin County in September 2022. Six mixes were included in short test sections: (1) a control mix with no RAS or RAP, (2) a mix with 25% RAP and recycling agent (RA) (3) a mix with 30% RAP and RA, (4) a mix with 35% RAP and RA, (5) a mix with 40% RAP and RA, and (6) a mix with 25% RAP, 3% RAS, and RA. A seventh mix, which was a typically used mix with 12% RAP and no RA, was used for construction of the rest of the overall project. This technical memorandum presents the laboratory test results from plant mix produced for job mix formula verification and from one or two quality assurance (QA) samples, depending on the test, taken during test section construction, as well as observations of plant production and construction. None of the mixes passed the Delta Tc specification, which is not uncommon...

Performance Evaluation of Recycled and Virgin Fibers in Fiber-Reinforced Concrete for Pavement Applications—Laboratory Test Results

Mon, 8 Jun 2026 00:00:00 +0000

This study evaluates the performance of recycled and virgin fibers in fiber-reinforced concrete (FRC), with a focus on workability, concrete production, and mechanical properties. Fibers were directly sourced from manufacturers and used at dosages recommended by manufacturers and supported by the literature. All fibers improved the modulus of rupture of plain (control) concrete. The fibers investigated included plastic, steel, composite, glass, and basalt fibers. Across most fiber types—regardless of whether they were virgin or recycled—FRC demonstrated improved post-cracking load-carrying capacity, resulting in enhanced residual strength and ductility. Plastic fibers exhibited the best post-cracking performance, with high residual strength, toughness, and effective flexural strength ratios, though they reduced workability. Recycled plastic fibers performed comparably to virgin plastic fibers in terms of post-cracking behavior. Steel fibers had minimal impact on workability and...

Preliminary Assessment of Effects of Gross Vehicle Weight Limit Increases for Trucks on Pavement Life and Cost

Mon, 18 May 2026 00:00:00 +0000

In January 2022, the Caltrans Pavement Program asked the University of California Pavement Research Center (UCPRC) to provide a quick high-level estimate of the effects of gross vehicle weight limit increases for trucks on pavement performance and the associated impact on the costs of pavement maintenance (Maintenance budget) and rehabilitation (SHOPP budget). Caltrans is considering increasing the limit from current 80 kips to 88 kips. This technical memorandum was delivered in February 2022. It was updated based on Caltrans comments in the same month and used internally by Caltrans but was not published. In September 2024 the Pavement Program requested that the UCPRC publish the technical memorandum. The results show that the high-level estimate is that the Maintenance and SHOPP budgets for pavement will need to increase by approximately 6% over the current projected 10-year total cost of $20.2 billion, resulting in a 10-year total increase of approximately $1.2 billion.

Investigation into the Use of Reclaimed Asphalt Pavement in Gap- and Open-Graded Asphalt Rubber Mixes: Phase 2: Laboratory Testing of Aggregate Replacement and CalME Simulation

Wed, 25 Mar 2026 00:00:00 +0000

This report presents data and analysis completed to evaluate changes in mix properties and simulated mix performance in pavement structures when using coarse reclaimed asphalt pavement (RAP) materials in new gap- and open-graded rubberized hot mix asphalt (HMA) (structural performance for gap-graded mixes only) and to prepare recommendations and suggested specification language, if considered appropriate, for allowing the use of coarse RAP in gap- and open-graded rubberized hot mix asphalt. This report includes laboratory binder and mix testing, as well as CalME fatigue and reflective cracking simulation results for four plant-produced gap-graded rubberized hot mix asphalt (RHMA-G) mixes used on the Heavy Vehicle Simulator test track at the UCPRC. The four mixes had the same base binder and two aggregate gradations, both with and without RAP. Six laboratory-produced mixes were also tested, using rubberized binders from two field projects and two RAP sources. Three mixes were...

Twenty-Year Performance Review of Asphalt Concrete Long-LifePavements with Performance-Related Specifications

Wed, 18 Mar 2026 00:00:00 +0000

The first asphalt concrete long-life (AC Long Life) project was constructed in Los Angeles County on Route 710 (LA-710) near Long Beach in 2001/2004 and is now over 20 years old. Four more AC Long Life projects have been completed in California since then, three between 2011 and 2014 (TEH-5, SIS-5, SOL-5), and one in 2021/2022 (SAC-5). The goal of these AC Long Life projects was to achieve design lives of 30 years or 40 years (the standard Caltrans asphalt pavement design life was 20 years at the time). Measures taken to achieve those lives included the use of performance-related specifications for job mix formula approvals, higher compaction requirements, and the use of a three-layer asphalt concrete system for structural capacity. These measures required additional costs. Calculations indicate that the longer lives will result in life cycle cost reductions if they achieve the design lives. Hence, periodic performance evaluations are important, which is the purpose of this technical...

Evaluation of Sustainable and Cost-Effective Concrete Pavement Life

Thu, 12 Mar 2026 00:00:00 +0000

Caltrans jointed plain concrete pavements (JPCP) and continuously reinforced concrete pavements (CRCP) are currently designed for a 40-year life (based on 10% fatigue transverse cracking and 10 punchouts per mile criteria, respectively). While this is already a long-life design, there is the concern that it may not result in the minimum possible life cycle cost and environmental impacts. The current Caltrans Highway Design Manual (HDM), including the Rigid Pavement Design Catalog, and the Standard Specifications applicable to concrete pavements, are based on this 40 year design life. This study includes recommendations for the materials, design, and construction of concrete pavements aimed at extending the design life up to 100 years. These recommendations are based on existing knowledge and tools and indicate the changes necessary to Caltrans’s existingspecifications and practices. However, uncertainties remain in traffic load and climate predictions, as well as the limitations...

Cold Central Plant Recycling Study: Preliminary Determination of Maximum Time That Processed Material Can Be Stockpiled and Compacted

Tue, 17 Feb 2026 00:00:00 +0000

The objective of this preliminary study was to investigate the effect of delayed compaction and/or stockpiling of cold central plant recycled materials with foamed asphalt recycling agents and cement active fillers. The results are also considered applicable for emulsified asphalt recycling agents and in-place cold recycling. Given that hydrated lime is currently not permitted as an active filler for cold recycled materials in Caltrans specifications, no tests were conducted with lime, and no recommendations are made regarding stockpile time if lime is considered in the future. A separate study will need to be completed for lime if justified.

The following conclusions were drawn from the test results: (1) delayed compaction or stockpiling results in reduced material workability—characterized by lower densities, strengths, and stiffnesses—which in turn will result in shorter pavement life, (2) delayed compaction or stockpiling can further increase variability in terms...

RAP and RAS in HMA Pilot Project on SBD 215: Material Testing, Observations, and Findings

Tue, 17 Feb 2026 00:00:00 +0000

A pilot project for the inclusion of high percentages of reclaimed asphalt pavement (RAP) in hot mix asphalt (HMA) was built on State Route 215 in San Bernardino County in September 2022. Five mixes were included in short test sections: (1) a control mix with no recycled asphalt shingles (RAS) or RAP, (2) a mix with 25% RAP and recycling agent (RA), (3) a mix with 30% RAP and RA, (4) a mix with 35% RAP and RA, and (5) a mix with 40% RAP and RA. A sixth mix, which was a typically used mix with 23% RAP, was used for construction of the rest of the overall project. This technical memorandum presents the laboratory test results from plant mix produced for job mix formula verification and from one or two quality assurance (QA) samples, depending on the test, taken during test section construction as well as observations of plant production and construction. Only the control mix binder consisting of the virgin PG 64-28M base binder and the mix with PG 58-34M, 25% RAP, and RA passed...

Update of the PG Binder Map in California Using the Enhanced Integrated Climate Model (EICM) and LTPPBind Online

Wed, 19 Nov 2025 00:00:00 +0000

Nine climate regions in California for mechanistic-empirical pavement design were identified in 2005 using data from weather stations in the National Climatic Data Center (NCDC) from 1961 to 1990, along with data from the Climatic Database for Integrated Model from 1976 to 1995. The climate data were analyzed using the Enhanced Integrated Climatic Model (EICM) software to predict pavement temperatures at different depths, including 28 different flexible pavement structures. For asphalt pavement, the most important environmental variable is temperature. The 2005 climate region map also included asphalt binder performance grades (PG) for each climate region, developed using EICM and Long-Term Pavement Performance (LTPPBind) (v.2.0), resulting in four different PG grades for the nine regions. The number of PG grades was reduced from a larger number identified by the PG binder grade specification criteria to simplify the number of grades that would need to be produced in the state.

This...

Feasibility of Cold Central Plant Recycling Asphalt Mixtures for Airports: Task 1 Report

Thu, 6 Nov 2025 00:00:00 +0000

This report summarizes the work completed in Phase 1 of a study to investigate the feasibility of using cold central plant recycled (CCPR) asphalt mixtures on airport pavements. Tasks within this phase included a literature review, laboratory and limited accelerated wheel load testing, development of a procedure for designing airport pavements that include a recycled layer, development of test plans for accelerated pavement testing at the FAA’s William J. Hughes facility, development of specifications for constructing the cold central plant recycled layers on the test track, and development of just-in-time training for all personnel participating in the construction of the test track. The specifications and just-in-time training deliverables will be revised for general use based on observations and feedback from construction of the test track.

The primary conclusions from the study include the following: (1) there is limited published literature on the use of cold recycled...

Development of Thin Bonded Concrete Overlay of Asphalt Design Method: Evaluation of Existing Mechanistic-Empirical Design Methods

Sun, 10 Aug 2025 00:00:00 +0000

The California Department of Transportation (Caltrans) is interested in advancing the technology needed to implement thin bonded concrete overlay of asphalt (BCOA) on its road network. Recent accelerated pavement tests showed that thin BCOA exhibited promising results for structural performance and constructability in California’s dry environment when made with the high early-strength concrete mixes typically used by Caltrans. However, to continue moving forward, Caltrans needs to adopt a thin BCOA design method since the current Caltrans Highway Design Manual does not consider this type of pavement. In order to help Caltrans decide how to adopt a thin BCOA design method, this technical memorandum includes an evaluation of two existing mechanistic-empirical methods: BCOA-ME, developed by the University of Pittsburgh, and MEPDG, as implemented in Pavement ME Design versions 2.3 (2016) and later. The evaluation includes a sensitivity analysis that considered the most important factors...

Cold Recycling Study: Testing to Develop Standard Mix Design and Quality Control/Quality Assurance Testing Procedures for Cold Recycling Project Specifications (Metric Units)

Tue, 5 Aug 2025 00:00:00 +0000

This report summarizes the research to evaluate cold recycling mix design procedures and to standardize specifications for cold recycling. The study focused on a review of different test methods for specimen compaction and strength testing and different specification limits for emulsified and foamed asphalt. Important findings from the study include the following: (1) specimen densities from Marshall compaction are higher than gyratory compaction and nuclear gauge field densities, (2) gyratory compaction using 30 gyrations is typically marginally higher than field density, (3) indirect tensile strength (ITS) and stability are strongly correlated to density, (4) mix designs done with Marshall compaction may underestimate binder and cement content requirements, (5) using Marshall compaction to compact specimens for quality control testing can result in strengths that are not representative of those on the road (i.e., higher), thereby potentially meeting the passing requirement in...

Cold Recycling Study: Testing to Develop Standard Mix Design and QualityControl/Quality Assurance Testing Procedures for Cold Recycling Project Specifications (Imperial Units)

Tue, 5 Aug 2025 00:00:00 +0000

This report summarizes the research to evaluate cold recycling mix design procedures and to standardize the specifications for cold recycling in California. Questions were developed based on a review of relevant test methods surrounding the options for specimen compaction and the difference in strength testing method and specification limits for emulsified asphalt and foamed asphalt. Important findings from the study include the following:• Specimen densities from Marshall compaction are higher than gyratory compaction and field densities measured with a nuclear gauge and corrected for gravimetric moisture content.• Gyratory compaction using 30 gyrations is typically marginally higher than field density.• Indirect tensile strength (ITS) and stability are strongly correlated to density.• Mix designs done with Marshall compaction may underestimate binder and cement content requirements.• Using Marshall compaction to compact specimens for quality control testing can result in strengths...

Cold Central Plant Recycling Study: First-Level Analysis of Heavy Vehicle Simulator Testing

Mon, 4 Aug 2025 00:00:00 +0000

This first-level analysis research report summarizes the construction and instrumentation of a test track to study the behavior of cold recycled layers containing 100% recycled asphalt pavement (RAP) materials in a pavement structure (recycled in place or through a central plant), a first-level analysis of the results from six Heavy Vehicle Simulator (HVS) tests, and a forensic investigation. The six HVS tests covered three recycling agents, testing at two pavement temperatures (30°C [86°F] and 50°C [122°F] at 50 mm [2 in.] depth), and two moisture conditions (as-compacted and under constant water flow). The same loading program was followed on all sections, and testing was continued until either terminal rut (12.5 mm [0.5 in.]) or terminal cracking (2.5 m/m2 [0.76 ft./ft2]) was reached. A review of all HVS test data, together with observations from the forensic investigation, indicates that localized shear failures in the aggregate base after heavy rainfall and issues associated...

Test Method Selection and Validation to Replace the R-Value Test

Thu, 29 May 2025 00:00:00 +0000

This technical memorandum summarizes a study that investigated the use of a confined compressive strength (CCS) test to replace the R-value test currently used for some pavement design and for quality control/quality assurance in California. The report covers a literature review, development of an alternative test, and a comparison of the results from the proposed test with R-value results.

The following are conclusions made based on the findings. First, California Test 216 needs revision. The compaction density reported by the test method is lower than the physical density of the compacted specimen in the CT 216 apparatus. The reported CT 216 density is approximately 88% of Modified Proctor density. Second, the proposed specimen compaction procedure, using Modified Proctor as the reference density, produced unbound specimens that could be handled and tested in a triaxial cell. Third, there is no correlation between the R-value test and the CCS test for the materials...

100% RAP Pilot Project on SBD 40: Material Testing, Life Cycle Assessment, Observations, and Findings

Fri, 16 May 2025 00:00:00 +0000

This report presents data and analysis of a new mix type that has 100% replacement of aggregate and asphalt binder with reclaimed asphalt pavement (RAP) and the addition of a recycling agent. The data were collected from construction of a pilot project on Interstate 40 in San Bernardino County, which included the new mix , HyRAP® (a registered trademark owned by Brooks Construction Company, Inc. and licensed to Manhole Adjusting Inc. but produced under a non-proprietary Caltrans Non- Standard Special Provision), the control gap-graded rubberized hot mix asphalt (RHMA-G), and a dense-graded polymer- modified mix (HMA-M) that was used in wheelpath digouts on the project. The report includes performance-related testing, a life cycle assessment, and a summary of observations from the construction of the pilot project. It also includes deflection testing results for the test sections and outside the test sections to check if they have similar underlying support. The life cycle assessment...

Final Noise and Smoothness Monitoring on Concrete Pilot Projects of Grind and Groove and Continuously Reinforced Concrete Pavements

Wed, 30 Apr 2025 00:00:00 +0000

The goal of this report is to conclude the project titled “Quieter Pavement Long-term Monitoring” by completing the measuring of noise and smoothness on previously built jointed plain concrete pavements (JPCP), surfaced with conventional diamond grinding (CDG) or the new grind and groove (GnG), and on continuously reinforced concrete pavement (CRCP). Previous studies have initiated the investigation into both the noise properties of GnG and CRCP. This project gathered data in 2018 and again in 2020 on the performance of these concrete pavements in terms of noise and smoothness. These data were added to the noise database to further the development of specifications, guidelines, and standardized field test methods toward quieter pavements. The GnG technology on test sections in Caltrans pilot projects was evaluated in terms of measured tire/pavement noise, smoothness, friction, and surface drainability. The results of this study are to be used to further incorporate quieter pavement...

Literature Review and Industry Survey of Recycled Fibers from Novel and Existing Source Materials for Concrete Use

Mon, 7 Apr 2025 00:00:00 +0000

Research has demonstrated the multiple benefits of fibers for the early and late-age performance of concrete pavements and bridge decks. Many research studies have also shown that the expected enhancements in properties of concrete with recycled fibers could be commensurate with those of concrete reinforced with virgin fibers. However, compared with virgin polymeric fibers and steel fibers from primary steel, recycled fibers and fibers from natural sources are not as commonly implemented in construction due to several barriers. Some of these obstacles include a lack of research on recycled fibers, leading to gaps in technical performance data, case studies, test tracks, and pilot projects. The primary reason for the lack of research is related to gaps in information regarding the quality of recycled fibers compared to virgin fibers. To help overcome some of these barriers, this study included a comprehensive survey of concrete fiber suppliers. Those suppliers with recycled fiber...

Analysis of 30 Years of Pavement Temperatures using the Enhanced Integrated Climate Model (EICM)

Wed, 26 Mar 2025 00:00:00 +0000

In this study, databases for rainfall and temperatures were developed for six climate regions of California. The weather data was obtained from National Climatic Database Center (NCDC). The pavement temperatures were simulated using Enhanced Integrated Climatic Model (EICM) software. Hourly pavement temperatures at the critical depths in the pavement layers were obtained using EICM for six cities, one in each of the identified climate regions.The objectives of the study presented in this report are:- Create a database of hourly pavement temperatures predicted using EICM for 30 years (1961-1990) for typical California pavements including hourly averages and standard deviations of pavement temperatures for each of the six California climate regions.- Evaluate the stability of pavement temperatures and rainfall across different 5-year periods to determine whether 5 years of data is sufficient to characterize a climate region.- Qualitatively evaluate the effects of pavement temperatures...

Climate Regions for Mechanistic-Empirical Pavement Design in California and Expected Effects on Performance

Wed, 26 Mar 2025 00:00:00 +0000

Chapter 2 contains an outline of the methodology of this study. The methodology includes a characterization of the climates studied, a brief introduction to the software used to estimate pavement temperatures, and an outline of assumptions. Chapter 3 presents analysis of the pavement temperature and thermal gradient data. The analysis is organized according to pavement type and distress type. Chapter 4 presents an overview of the rainfall data. Chapter 5 presents the conclusions drawn from the data analysis and recommendations for inclusion of the results in current Caltrans operations and in the mechanistic-empirical design procedure being developed for Caltrans by the University of California Berkeley Contract Team.

State Route 138: Test Site Evaluation Update of Evaluation Activities in March and October 2002

Wed, 26 Mar 2025 00:00:00 +0000

In 2001, Caltrans Maintenance selected a segment of State Route 138 in Los Angeles County to create test sections for the evaluation of pavement/tire noise measurements and performance of several maintenance treatments. In March 2001, the Caltrans Partnered Pavement Research Center (PRC) Contract Team (staff from University of California Pavement Research Center and Dynatest Consulting Inc.) collected and analyzed pavement data from the segment, and recommended test section locations that would provide the most uniform underlying pavement structures possible.(1) The objective of identifying uniform underlying pavement structures was to provide the most unbiased evaluation possible of the performance of the various treatments.The data used to select the sections included:- Visual surface condition survey to identify existing distresses,- Deflection testing using a Falling Weight Deflectometer (FWD) and accompanying deflection analysis and back-calculation of stiffnesses,- Coring...

Goal 4 Long Life Pavement Rehabilitation Strategies—Rigid: Laboratory Strength, Shrinkage, and Thermal Expansion of Hydraulic Cement Concrete Mixes

Wed, 26 Mar 2025 00:00:00 +0000

This report presents the results of laboratory work on flexural and compressive strength, free shrinkage, coefficient of thermal expansion, and elastic modulus performed on six concrete mixes. The six concrete mixes are typical of those used, or have been considered for use, for the Caltrans Long Life Pavement Rehabilitation Strategies for rigid pavements (LLPRS-Rigid).

The work presented in this report was completed as part of Goal 4 of the Partnered Pavement Research Program Strategic Plan, and completes the following objectives of the test plan for that research goal: - -

- Evaluation of, and development of recommendations for test methods for strength gain, ultimate strength and stiffness, thermal expansion, and shrinkage.

- Development of laboratory data regarding the properties of various high earlystrength concrete mixes, and comparison with a typical Type I/II mix.

- Development of laboratory data regarding the effects of important mix design...

Durability Testing of LCB and CTB Materials Supplied by Caltrans

Wed, 26 Mar 2025 00:00:00 +0000

Carbonation of cement-stabilized layers under concrete pavements in California was investigated as a potential reason for faulting of these pavements. In discussions with personnel from the Pavement Research Center, it was mentioned that a layer of loose material is often observed between the concrete slab and the supporting cement stabilized layer. Samples of materials commonly used under concrete slabs were sent to South Africa for durability testing using South African test methods. These test methods were primarily developed at the CSIR, Transportek, for the purpose of durability assessment of stabilized materials. The materials supplied by Caltrans consisted of samples of two aggregates used to make cement treated base (CTB) and lean concrete base (LCB). The aggregate sources for these materials were, named Mission Valley and Lake Herman. Details of gradings, water content, and cement content were provided with the samples. These materials were tested for durability using...

Performance of Drained and Undrained Flexible Pavement Structures in Accelerated Loading Under Wet Conditions–Summary Report Goal 5 Partnered Pavement Performance Program

Wed, 26 Mar 2025 00:00:00 +0000

The California Department of Transportation (Caltrans) requires that all new flexible pavements include a 75-mm layer of asphalt treated permeable base (ATPB) between the asphalt concrete and the aggregate base layers. The purpose of the ATPB layer is to intercept water entering the pavement because of high permeability resulting from insufficient compaction or through cracks in the asphalt concrete layer and transport it away from the pavement before it reaches the unbound materials.This reports summarizes the results of a study using Heavy Vehicle Simulator (HVS) trafficking to evaluate the performance of drained and undrained flexible pavements under wet (saturated base) conditions. A drained structure is a pavement section that contains an ATPB layer between the asphalt concrete and the aggregate base. An undrained structure is a pavement section that does not contain an ATPB layer. Wet conditions used in this study were intended to simulate approximate surface infiltration...

Stiffness, Strength, and Performance of Unbound Aggregate Material: Application of South African HVS and Laboratory Results to California Flexible Pavements

Wed, 26 Mar 2025 00:00:00 +0000

Caltrans specifies the use of a 75-mm Asphalt Treated Permeable Base (ATPB) layer as standard practice for all new flexible pavement designs in California.(1) The ATPB acts as a drainage layer beneath the asphalt concrete (AC) and is supported by an aggregate base layer. However, the potential exists for water to enter the unbound aggregate base layer from the ATPB layer through the prime coat that separates them. The stiffness, strength, and performance of unbound aggregate layers are largely influenced by moisture content.The assessment of the performance of two types of flexible pavement cross section, one with and one without an ATPB layer, were included in the strategic plan of the CAL/APT program (1994-2000). Goal 1 and Goal 5 of the CAL/APT project (continued in the Partnered Pavement Research Program after 2000) consist of the evaluation of these two sections under dry and wet base conditions, respectively.The evaluation includes accelerated pavement testing using the...

Evaluation of Recycled Asphalt Concrete Materials as Aggregate Base

Wed, 26 Mar 2025 00:00:00 +0000

This technical memorandum summarizes the evaluation of a rehabilitation strategy that involves recycling an existing asphalt concrete surface and a portion of the base material into a new base layer. A series of field and laboratory tests were conducted to evaluate this rehabilitation strategy. Field tests included destructive and non-destructive testing conducted on a pavement section located on California State Highway 395 between PM 13 and PM 10, which is about 10 miles south of Alturas, CA. For purposes of analysis and discussion, the starting station is 0.0 (m) at PM 13 and the ending station is 4800.0 (m) at PM 10. The recycling process was conducted between stations 0.0m and 3125.0 m. Laboratory tests included static and dynamic tests on the recycled asphalt concrete and two California aggregate base class 2 materials.The objectives of the study are (1) to evaluate the performance of the recycling process in the field by analyzing destructive and non-destructive data before...

Accelerated Laboratory Testing for Alkali-Silica Reaction Using ASTM 1293 and Comparison with ASTM 1260

Wed, 26 Mar 2025 00:00:00 +0000

A great deal of work on alkali-silica reactivity (ASR) has been reported since1940. ASR is a reaction in which certain aggregates react with the highly alkaline pore solution of concrete. As the name of the reaction implies, the reactive aggregate contains silica. However, not all siliceous aggregates are reactive.In general, the aggregates that cause harmful reactions in concrete are those containing amorphous silica (glasses and opal), unstable crystalline polymorphs of silica (cristobalite and tridymite), poorly crystalline forms of silica (andesite and rhyolite), and microcrystalline quartz-bearing rocks (quartzite and greywacke). The highly alkaline pore fluids of concrete are able to depolymerize the reactive silica present in the aggregates, forming products of different compositions in the concrete pores. In the presence of moisture, the reaction products (gel products) change in volume and may expand to such a degree that the concrete tensile strength is reached and the...

Performance of Drained and Undrained Flexible Pavement Structures Under Wet Conditions – Accelerated Test Data, Test Section 545–Undrained

Wed, 26 Mar 2025 00:00:00 +0000

This report is the third in a series that describes the results of accelerated pavement testing conducted on full-scale pavements at the Richmond Field Station (RFS). The report contains a summary of the results and associated analyses of a pavement section composed of three lifts of asphalt concrete and an untreated aggregate base layer on top of a prepared subgrade. The pavement section is termed an undrained pavement because it does not include an ATPB layer between the asphalt concrete layers and the untreated aggregate base. The pavement structure was designated Section 545. The tests on this test section have been performed as part of the Goal 5 Accelerated Test Program for the evaluation of drained and undrained pavements under conditions of water infiltration. The main objective of the test program is to develop data to quantitatively compare and evaluate the performance of reduced thickness asphalt rubber hot mix (ARHM) and full thickness of dense graded asphalt concrete...

CAL/APT Program – Construction of the Goal 3 Overlays and Recommendations for Improved Overlay Performance in California

Wed, 26 Mar 2025 00:00:00 +0000

This report describes the construction of the CAL/APT Goal 3 overlays and details observations regarding current Caltrans procedures which are intended to help improve the performance of Caltrans overlays. The main objective of Goal 3 is the comparison of the performance of a Gap Graded Asphalt Rubber Hot Mix (ARHM-GG) overlay with that of a conventional Dense Graded Asphalt Concrete (DGAC) overlay. Based on Caltrans design procedures, ARHM-GG overlay thicknesses are typically half of the equivalent DGAC overlay. These overlays represent typical pavement structures currently in use throughout California (1). The complete plan for HVS and laboratory testing and associated analyses is outlined in the Goal 3 test plan (9).

CAL/APT Program: Test Results from Accelerated Pavement Test on Pavement Structure Containing Asphalt Treated Permeable Base (ATPB)–Section 502CT

Wed, 26 Mar 2025 00:00:00 +0000

This report is the third in a series which describe the results of tests and their interpretation on full-scale pavements designed and constructed according to the procedures of the California Department of Transportation (Caltrans) at the Richmond Field Station (RFS) of the University of California at Berkeley (UCB). It describes the results of the Heavy Vehicle Simulator (HVS) test on the third of four pavement test sections, an asphalt-concrete section containing an asphalt treated permeable base (ATPB) designated Section 502CT. The tests on these four test sections have been performed as part of Goal 1 of the Strategic Plan of the Caltrans Accelerated Pavement Testing, or CAL/APT program (1).

Analysis of Sensitivity of Plain Jointed Concrete Pavement in California to Early-Age Cracking Using HIPERPAV

Wed, 26 Mar 2025 00:00:00 +0000

The work included in this report completes the first of the three objectives of the earlyage cracking investigation plan. This report also presents preliminary recommendations for the use of HIPERPAV and for the mitigation of early-age cracking based on the HIPERPAV sensitivity analysis.

Normalizing the Behavior of Unsaturated Granular Pavement Materials

Wed, 26 Mar 2025 00:00:00 +0000

One of the important components of a flexible pavement structure are granular material layers. The unsaturated granular pavement materials (UGPMs) in these layers influence stresses and strains throughout the pavement structure, and can have a large effect on asphalt concrete fatigue and pavement rutting, which are two of the primary failure mechanisms for flexible pavements. The behavior of UGPMs is highly dependent on water content, but this effect has been traditionally difficult to quantify using either empirical or mechanistic methods.This report presents a mechanistic framework for normalizing the behavior of UGPMs within the range of water contents, densities, and stress states likely to be encountered under field conditions. Both soil suction and generated pore pressures are calculated and compared to applied confinement under typical field loading conditions. The framework utilizes a new soil suction model that has three density-independent parameters, and can be determined...

Assessing the Economic Benefits from the Implementation of New Pavement Construction Methods

Wed, 26 Mar 2025 00:00:00 +0000

This report is organized in the following way: Section 2 provides a brief overview of the current state of the art in road building technologies and methods. The new methods of road building and maintenance that are being advocated are described in detail in Section 3. In Section 4, the attributes of the sample of roadway sections selected for analysis are identified and the methodology is described. Section 5 compares the differential costs of old and new approaches to pavement technologies as well as discusses calculations of the projected savings to Caltrans if it were to adopt the new approach as standard practice in roadway maintenance and rehabilitation. Section 6 contains estimates of the differential returns from the application of different types of new pavement technology including, increased compaction, use of a tack coat, and use of a rich bottom layer. Section 7 contains the summary and conclusions.

Analysis and Estimation of Effective Built-In Temperature Difference for North Tangent Slabs: Data Analysis from the Palmdale, California Rigid Pavement Test Site

Wed, 26 Mar 2025 00:00:00 +0000

As part of the California Department of Transportation (Caltrans) Long Life Pavement Rehabilitation Strategies (LLPRS), a high early strength hydraulic cement was field tested using the Heavy Vehicle Simulator (HVS). This fast-setting hydraulic cement concrete (FSHCC) was designed to gain enough strength to allow it to be opened to traffic within 4 hours of placement. The objective of the HVS tests was to evaluate the performance of this concrete under the influence of simulated loads along with pavement design features such as dowels, tied concrete shoulder, and a wide truck lane that had not previously been implemented in California.Two full-scale test pavements, each approximately 700 ft. (215 m) in length, were constructed on State Route 14 about 5 miles (8 km) south of Palmdale, California using FSHCC. The South Tangent was constructed along State Route 14 southbound and was used to conduct a fatigue evaluation of the FSHCC with three thicknesses of PCC [4, 6, and 8 in. (100,...

CAL/APT Program: Test Results from Accelerated Pavement Test on Pavement Structure Containing Untreated Aggregate Base–Section 503RF

Wed, 26 Mar 2025 00:00:00 +0000

This report is the fourth in a series which describe the results of tests and their interpretation on full-scale pavements constructed at the Richmond Field Station (RFS) which have been designed and constructed according to Caltrans procedures. It describes the results of the Heavy Vehicle Simulator (HVS) test on the fourth of four pavement test sections, an asphalt-concrete section containing an untreated aggregate base designated Section 503RF. The tests on these four test sections have been performed as part of Goal 1 of the CAL/APT Strategic Plan.

Shrinkage and Thermal Cracking of Fast Setting Hydraulic Cement Concrete Pavements in Palmdale,California

Wed, 26 Mar 2025 00:00:00 +0000

Jointed Plain Concrete Pavement (JPCP) test sections were constructed using Fast Setting Hydraulic Cement Concrete (FSHCC) as part of the California accelerated pavement testing program (CAL/APT). Many of the longer slabs cracked under environmental influences before any traffic load was applied to them. Cores drilled through the cracks indicated that cracking initiated at the top of the slabs and propagated downwards. Concrete shrinkage and thermal strain data from field instrumentation was recorded and analyzed along with laboratory test data to determine the cause of the cracking. Finite element analysis using the measured strains and temperatures predicted high tensile stresses at the top of the test section slabs as a result of the differential drying shrinkage between the top and base of the slab and the non-linear nature of the negative temperature gradients through the slab. Laboratory free shrinkage tests on the test section cement indicated significantly higher shrinkage...

Accelerated Laboratory Testing for High Early StrengthConcrete for Alkali Aggregate Reaction

Wed, 26 Mar 2025 00:00:00 +0000

Aggregate makes up a significant portion of concrete. However, unlike cement, there are limited choices as to the composition and source of aggregate to be used. It has been shown in the laboratory and in the field that certain types of aggregate can cause deleterious expansion through a reaction known as alkali-silica reaction (ASR). In order to ensure the durability of new pavements and projects, the susceptibility of aggregates and cements need to be investigated. An accelerated test for ASR susceptibility was used in which mortar bar length changes were measured and used to indicate the potential of being reactive. Aggregate consisting of granite, mylonite, phyllonite, and ultramylonite were tested. These aggregates have the same chemical and mineralogical composition, however they all have differences in grain size. For the samples studies, smaller grain size indicated a higher amount of deformation. Two aggregate types were chosen for which the different types of cements...

Evaluation of the Maturity Method for Flexural Strength Estimation in Concrete Pavement

Wed, 26 Mar 2025 00:00:00 +0000

The primary purpose of the work presented in this report is to provide Caltrans with information regarding the accuracy and feasibility of the maturity method for the measurement of concrete flexural strength. Information is also provided regarding use of the maturity method for measurement of compressive strength.

Palmdale South Tangent Slab Built-In Curling and Cracking: Preliminary Analysis Report

Wed, 26 Mar 2025 00:00:00 +0000

This report presents a preliminary analysis of slab cracking at the South Tangent sections tested at Palmdale, California using the Heavy Vehicle Simulator (HVS). The data collected on the South Tangent include corner and edge deflections, thermocouple data representing temperature distribution through the slabs, visual and photographic crack surveys, crack activity measurement data, multi-depth deflection data representing deflections at various depths beneath the pavement surface, slab strains measured at critical locations using strain gages, and falling weight deflectometer (FWD) data. The primary focus of this report is the preliminary cracking analysis of the South Tangent slabs. The chief tool used in this analysis is the finite element program, ISLAB2000, which is used to estimate pavement responses for a given geometry under the influence of wheel loadings and layer temperature profiles. The key data used in the analysis include measured corner deflections, thermocouple...

Rutting of Caltrans Asphalt Concrete and Asphalt-Rubber Hot MixUnder Different Wheels, Tires and Temperatures – AcceleratedPavement Testing Evaluation

Wed, 26 Mar 2025 00:00:00 +0000

This report presents results from accelerated pavement tests using the Caltrans Heavy Vehicle Simulator (HVS) of DGAC and ARHM-GG overlays placed at the University of California, Berkeley Pavement Research Center. The results in this report are from tests conducted at elevated temperatures to evaluate the rutting performance of the two overlay strategies. The tests also investigated the effects of tire type, temperature and thickness of the ARHM-GG overlay. The overlays were placed on existing flexible pavement structures, sections of which were previously tested as part of CAL/APT Goal 1 (5-9). The mix designs and thickness designs for the overlays and their construction are included in References (10, 11).

HVS Test Results on Fast-Setting Hydraulic Cement Concrete, Palmdale, California Test Sections, South Tangent

Wed, 26 Mar 2025 00:00:00 +0000

As part of the Caltrans Long Life Pavement Rehabilitation Strategies (LLPRS), a fast setting strength hydraulic cement concrete (FSHCC)/Type I/II portland cement concrete (PCC) blend was evaluated under Heavy Vehicle Simulator (HVS) tests as detailed in the Test Plan for CAL / APT Goal LLPRS - Rigid Phase III (1). Because it is expected to be used on projects where heavy trucks are expected to be allowed on the slabs within 4 to 8 hours after placement, this newly placed concrete is specified to obtain a flexural strength of 2.8 MPa within 4 to 8 hours of placement. Two full-scale test sites, each approximately 210 m in length, were constructed using this concrete on either side of State Route 14 about 5 miles south of Palmdale, California. Various test sections were constructed at these two sites. The site in the southbound direction included sections with different thicknesses of concrete placed on compacted granular base. The site in the northbound direction included 200-mm...

Performance of Caltrans Asphalt Concrete and Asphalt-Rubber Hot Mix Overlays at Moderate Temperatures—Accelerated Pavement Testing Evaluation

Wed, 26 Mar 2025 00:00:00 +0000

This report presents results from accelerated pavement tests using the Caltrans Heavy Vehicle Simulator (HVS) of DGAC and ARHM-GG overlays placed at the University of California Berkeley Pavement Research Center. The results presented in this report are from four tests conducted at 20 degrees C to evaluate the performance of the two overlay strategies with respect to cracking (fatigue or reflection), and rutting of the unbound pavement layers. Both overlay strategies were evaluated on previously tested drained and undrained flexible pavement structures. The overlays were placed on existing flexible pavement structures, sections of which were previously tested as part of CAL/APT Goal 1. The mix designs and thickness designs for the overlays and their construction are included in References (10, 11).

Data Mining of the Caltrans Pavement Management System (PMS) Database

Wed, 26 Mar 2025 00:00:00 +0000

Since 1977, Caltrans has been routinely collecting performance information for its pavement network and using a pavement management system (PMS) to manipulate this information in order to aid in the management of the network. This report details the "mining" of this database to extract environmental performance indicators for the various climate regions in California, and to extract section information for portland cement concrete (PCC) pavements that have been overlaid with asphalt concrete (with the specific goal of obtaining information regarding the reflection cracking performance). The first objective of this study is to provide the best possible estimate of the performance of the standard Caltrans strategy for asphalt concrete overlays of PCC pavements, to provide an estimate to Caltrans, and to provide calibration data for the development of mechanistic-empirical models for reflection cracking. The second objective of this study is to provide recommendations for short-term...

Constructability and Productivity Analysis for Long Life Asphalt Concrete Pavement Rehabilitation Strategies

Wed, 26 Mar 2025 00:00:00 +0000

A large portion of the highway system in the United States has exceeded its design and its service life. Deterioration of the existing highway system adversely affects the safety of road users, ride quality, the operational cost of vehicles, and the cost of highway maintenance. This report presents the results of a constructability and productivity analysis for the Caltrans Long Life Asphalt Concrete Pavement Rehabilitation Strategies (LLACPRS), focusing on optimizing the maximum production capability within a 55-hour weekend closure.With the assistance of California asphalt concrete paving contractors, the constructability analyses explored the effects of the following parameters: rehabilitation materials, design profile [Crack Seat and Overlay (CSOL) and Full-Depth Asphalt Concrete (AC) replacement of different thickness], cooling time, number and capacity of construction resources, and alternative lane closure strategies. The experiment design consisted of a hierarchical structure...

High Percentages of Reclaimed Asphalt Affect the Performance of Asphalt Binder

Wed, 12 Mar 2025 00:00:00 +0000

More than 90 percent of the road and highway network in the United States is paved with asphalt concrete. Maintenance and periodic rehabilitation require a continuous supply of aggregates and asphalt binder, both of which are becoming increasingly scarce and expensive. Recycling and reusing these resources can reduce costs and improve sustainability. The most common recyclable material used in road construction is reclaimed asphalt pavement (RAP), which is milled asphalt surface layers that have been removed from existing pavements before new asphalt overlay is placed. Reclaimed asphalt roofing shingles (RAS) are another potential source of asphalt binder.

There is growing interest in allowing significantly higher percentages of RAP and RAS in asphalt mixes used on state and local roadways. However, making this change has raised concerns regarding how these composite binders may influence the performance and durability of asphalt mixes, depending on the blends of different...

Development of Hot Mix Asphalt Pavement Performance Properties for Long-Life Pavement Design: Caltrans District 4, Interstate-80 Solano County, California

Wed, 5 Mar 2025 00:00:00 +0000

In the period 2012 to 2014 Caltrans designed and built three long-life asphalt pavement (LLAP) rehabilitation projects. Two projects were in District 2 on Interstate 5—one just north of the city of Red Bluff and the other on the interstate running through and north of the city of Weed—and one in District 4 on Interstate 80 in Solano County between the cities of Dixon and Vacaville. This technical memorandum describes the processes by which performance criteria were developed for a pavement section that is part of the LLAP project on Interstate 80. This pavement section, designed and constructed as an LLAP section, consisted of the following pavement components: A hot mix asphalt (HMA) surface course containing a polymer-modified asphalt (PG 64-28PM) with 15 percent reclaimed asphalt pavement (RAP) and a representative virgin aggregate from the local area treated with 1.2 percent lime (marinated). An HMA intermediate course containing a conventional asphalt binder (PG 64-10), and...

Pavement Environmental Life Cycle Assessment Tool for Local Governments

Wed, 5 Mar 2025 00:00:00 +0000

The processes in the pavement life cycle can be defined as: material extraction and production; construction; transport of materials and demolition; the use stage, where the pavement interacts with other systems; the materials, construction, and transport associated with maintenance and rehabilitation; and end-of-life. Local governments are increasingly being asked to quantify greenhouse gas emissions from their operations and identify changes to reduce emissions. There are many possible strategies that local governments can choose to reduce their emissions, however, prioritization and selection of which to implement can be difficult if emissions cannot be quantified. Pavement life cycle assessment (LCA) can be used by local governments to achieve the same goals as state government. The web-based software environmental Life Cycle Assessment for Pavements, also known as eLCAP has been developed a project-level LCA tool. The goal of eLCAP is to permit local governments to perform...

Early-Age and Premature Cracking in Jointed Plain Concrete Pavements: Literature Review

Mon, 3 Mar 2025 00:00:00 +0000

This technical memorandum includes a literature review about the factors that may lead to early-age and premature cracking of jointed plain concrete pavements (JPCPs). The review shows that many factors are involved and that many different circumstances can result in these types of cracking. In most of the cases reported in the literature, the early-age and premature cracking were related to poor construction practices. The early-age cracking of JPCP has already received considerable attention, and there is agreement regarding the mechanisms that result in this type of cracking and about the practices recommended to reduce it. The current version of the Caltrans Standard Specifications addresses most of these practices, but Caltrans specifications for paving in adverse weather conditions are not completely clear. Unlike the causes of early-age cracking on JPCP, premature cracking of JPCP has not been studied extensively. Further, even though it is widely recognized that the early-age...

Performance Based Specifications: Literature Review on Increasing Crumb Rubber Usage by Adding Small Amounts of Crumb Rubber Modifier in Hot Mix Asphalt

Fri, 28 Feb 2025 00:00:00 +0000

A comprehensive review of the literature covering more than 100 published journal articles, conference proceedings, and reports found that although considerable research has been undertaken to understand the advantages and disadvantages of using recycled tire rubber to modify asphalt binders, no published information on PG+X-type initiatives (i.e., focused more on using additional waste tires in asphalt mixes rather than on improving performance of the binder and mix) was found. A number of states have specifications that allow tire rubber as a substitution for styrene-butadiene-styrene (SBS) modification (e.g., California [PG-M], Florida [PG-ARB], and Louisiana [PG-CRM]). The quantities of rubber added and the properties of the rubber particles used are similar to one of the four approaches discussed in this Technical Memorandum: PG+X Approach-1. No published research on adding very small quantities (i.e., less than 0.5 percent by total weight of the mix) in a dry process...

Life Cycle Assessment of Asphalt Binder, Warm Mix Asphalt Additives, and Bonded Concrete Overlay of Asphalt for California Conditions

Fri, 28 Feb 2025 00:00:00 +0000

The UCPRC is updating and expanding the life cycle inventories (LCIs) that are available for materials, pavements, and practices being used in or introduced to California for use in the project-level design software, eLCAP, and in the Caltrans pavement management system,PaveM. This report presents the results of developing LCI for use in life cycle assessment (LCA) for three types of materials or pavement structures being used in California: (1) asphalt binder regionalized to California from a national average, (2) warm mix asphalt (WMA) technologies, and (3) bonded concrete overlay of asphalt (BCOA). These LCIs fill important gaps because asphalt binder environmental product declarations (EPDs) will not be available for several years and very few WMA EPDs are available. The results of the binder LCI showed that California has a typical asphalt binder global warming (GW) of 0.456 kgCO₂ eq/kg of binder compared to Petroleum Administration for Defense...

Evaluation of the Effect of Deflection Waveform on Fatigue Test Results for Hot Mix Asphalt

Fri, 28 Feb 2025 00:00:00 +0000

An experimental study was conducted to determine the effect of deflection waveform on four-point flexural fatigue test results for hot mix asphalt. Seven asphalt mixtures, comprising a wide variety of gradations, binder types, and binder contents, were selected for this study. Four of the mixes were tested at the University of California Pavement Research Center (UCPRC) and three were tested in Australia by the ARRB Group. The mixes were tested at different strain levels under both haversine and sinusoidal deflection-controlled modes without introducing rest periods between load cycles. The haversine and sinusoidal testing modes were compared to each other from different perspectives. This comparison showed no indications of differences in damage as measured by stiffness reduction between the haversine and sinusoidal waveforms for six of the seven mixtures. This outcome was attributed to the viscoelastic nature of asphalt mixes. Because of this viscoelasticity, it is believed...

Continued Noise and Smoothness Monitoring on Concrete Pilot Projects of Grind and Groove on Existing Pavement and Current Texture Types on Continuously Reinforced Concrete Pavements

Fri, 28 Feb 2025 00:00:00 +0000

The goal of this project, titled “Quieter Pavement Monitoring,” is to continue measuring noise and smoothness on previous concretepavement surfacing techniques and the new grind and groove (GnG) surface, and on continuously reinforced concrete pavement (CRCP).Previous studies have initiated the investigation into both the noise properties of GnG and CRCP. This project gathered data in 2016 andearly 2017 on the performance of these concrete pavements in terms of noise and smoothness. These data will be added to the noisedatabase to further the development of specifications, guidelines, and standardized field test methods toward quieter pavements. TheGnG technology on test sections in Caltrans pilot projects was evaluated in terms of measured tire/pavement noise, smoothness, friction,and surface drainability. The results of this study are to be used to further incorporate quieter pavement research into standard Caltranspractice and may serve as a basis for changes in quieter pavement...

Effects of Milling and Other Repairs on Smoothness of Overlays: Additional Testing on Construction Under Profiler-Based Smoothness Specifications

Fri, 28 Feb 2025 00:00:00 +0000

This technical memorandum provides additional information regarding smoothness on several thin asphalt overlay projects constructed soon after changes in Caltrans specifications for constructed pavement surfaces using the International Roughness Index (IRI) as the quality metric. The IRI data were collecting using inertial profilers, before and after construction, on overlaid surfaces employing one of three repairs—digouts, cold in-place recycling (CIR), mill and filling—or none. Because the data were collected after the close of the construction contract, they include the effects of any grinding that Caltrans required the contractor to perform prior to that close. However, the data provide a preliminary look at whether changes in the construction smoothness specification necessitate changes to any of the recommendations in a previous report regarding repairs before overlay. The results indicate that the recommendations in the previous report are generally being followed. The...

Permeability Testing on Dense-Graded Hot Mix Asphalt (HMA) and Gap-Graded Rubberized Hot Mix Asphalt (RHMA-G) Surfaces

Fri, 28 Feb 2025 00:00:00 +0000

Falling head permeability tests were conducted on seven projects, four with dense-graded hot mix asphalt surfaces and three with gap-graded rubberized hot mix asphalt surfaces. Tests were conducted between the two wheelpaths and in the right wheelpath, and in both directions of traffic. Averaging all the test results shows that the permeability of RHMA-G is much greater than that of HMA: 2.9E-3 cm/sec versus 6.1E-4 cm/sec, respectively. However, one of the three projects with a gap-graded rubberized hot mix asphalt surface had permeabilities not consistent with the other two. When data from that gap-graded rubberized hot mix asphalt surface was removed, the average value for the surface permeability dropped over 80 percent, to 4.2E-4 cm/sec. This average is lower than the average permeability for dense-graded hot mix asphalt, and the data remaining from the six projects—four dense-graded and two gap-graded—showed no statistical difference in the average surface permeability of...

Pavement Recycling: Literature Review on Shrinkage Crack Mitigation in Cement-Stabilized Pavement Layers

Fri, 28 Feb 2025 00:00:00 +0000

The California Department of Transportation (Caltrans) has been using full-depth reclamation (FDR) as a rehabilitation strategy since 2001. Most projects to date have used a combination of foamed asphalt and portland cement as the stabilizing agent. Recently, the increasing cost of asphalt binder coupled with the relatively complex mix-design procedure for foamed asphalt has generated interest in the use of portland cement alone as an alternative stabilizing agent, where appropriate. However, shrinkage cracking associated with the hydration and curing of the cement-stabilized layers remains a concern, especially with regard to crack reflection through asphalt concrete surfacings and the related problems caused by water ingress. Considerable research has been undertaken on crack mitigation, and a range of measures related to improved mix designs and construction practices have been implemented by road agencies. One of the most promising measures, used in conjunction with appropriate...

2021 Cold Recycling Pilot Projects: Construction and Quality Control

Fri, 28 Feb 2025 00:00:00 +0000

The construction of three partial-depth recycling (PDR) pilot projects was monitored in late 2021. These studies focused on the benefits of adding supplemental aggregates to PDR materials, comparison of emulsified asphalt (EA) and foamed asphalt (FA) recycling agents in PDR applications, comparison of the gradations produced by single- and multi-unit recycling trains, and the effect of recycling train forward speed on gradation. Initial findings from the study can be summarized as follows:• Statistical analyses of quality control results on in-place recycling projects are challenging given the variability in materials and pavement structure along the length of the project. The problem is intensified on pilot projects with multiple experimental sections on which performance is being compared. • Supplemental aggregates can be used to reliably increase the density and strength of PDR layers without increasing the recycling agent or active filler contents and by not requiring pre-milling...

Preliminary Results: Measurement of Macrotexture on Surface Treatments and Survey of Bicyclist Ride Quality on Mon-198 and SLO-1 Test Sections

Fri, 28 Feb 2025 00:00:00 +0000

This memorandum summarizes the results of measurements of macrotexture on a set of Caltrans pavement surface treatments, and the results of bicycle vibration measurements and a survey of bicyclists ride quality on a subset of those sections. The work was performed to address concerns raised by local bicyclists regarding the ride quality after a modified binder seal coat (chip seal) was placed on State Route 1 in San Luis Obispo County (SLO-1). The subset includes test sections for various surface treatments on existing chip seals on State Route 198 in Monterey County (Mon-198) and several locations on SLO-1. Macrotexture was measured in terms of mean profile depth (MPD). Three different test methods were used to measure MPD: the sand patch method and the laser texture scanner (LTS), which provide measurements on a small area at a single location (about 12 square inches [100 square cm]); and the inertial profiler (IP), which is mounted on a vehicle and provides a continuous measurement...

Impact of Silo Storage on the Performance of Plant-Produced Mixes Containing High Content of Reclaimed Asphalt Pavement or Reclaimed Asphalt Shingles

Fri, 28 Feb 2025 00:00:00 +0000

Use of recycled materials, such as reclaimed asphalt pavement (RAP) and reclaimed asphalt shingles (RAS), is gaining widespread interest. Currently the California Department of Transportation standard specifications do not allow the use of RAS and limit the use of RAP contents to a maximum of 25% by dry weight of aggregate, though there is a non-standard special provision that allows use of up to 3% RAS by mass of aggregate and 40% RAP content by binder replacement. Nevertheless, mixes with high RAP and RAS are being produced across California for local agencies and commercial use. This study investigated the performance of four plant-produced high RAP or RAS mixes collected from different regions in California. The mixes were not designed and produced following Caltrans specifications. However, they provide insight into the effects of silo storage time on blending of virgin and RAP binder, the performancerelated properties of these mixes, and the measurement of properties by...

Mix Design and Analysis and Structural Section Design for Full Depth Pavement for Interstate Route 710

Fri, 28 Feb 2025 00:00:00 +0000

This report summarizes the results of an investigation to design both a suitable asphalt concrete mix and a full-depth asphalt concrete structural section containing the mix, or mixes for a “Long Life Pavement” for a portion of Interstate 710 in Southern California. A companion report (Technical Memorandum, TM UCB PRC-99-3) desribes the asphalt concrete section for use as an overlay on the existing portland cement concrete pavement.

First-Level Analysis of Heavy Vehicle Simulator Testing on Three RHMA-G Mixes to Investigate Performance with Reclaimed Asphalt Pavement Aggregate Replacement

Fri, 28 Feb 2025 00:00:00 +0000

This technical memorandum summarizes a literature review update, elements of the construction of a test track to assess various aspects of gap-graded rubberized asphalt concrete (RHMA-G) mixes with and without the addition of reclaimed asphalt pavement (RAP) as aggregate replacement, and a first-level analysis of the results from the first three Heavy Vehicle Simulator (HVS) tests. Four different RHMA-G mixes were placed on seven sections on the test track at the UCPRC. Mixes differed by nominal maximum aggregate size (NMAS, 1/2 and 3/4 in.) and the addition of 10% RAP by weight of the aggregate as an aggregate replacement. Single and double lifts of each mix were placed. Apart from the addition of RAP, the mix designs all met current Caltrans specifications. Although Caltrans currently does not permit more than one lift of RHMA-G on projects, the placement of each lift of each mix on the test track met current Caltrans specifications for RHMA-G layers. The first three HVS tests...

Calibration of the CalME Rutting Model Using 2000 NCAT Data

Fri, 28 Feb 2025 00:00:00 +0000

CalME is a software package under development for Caltrans that is intended to help in the evaluation and design of flexible pavement structures. Building on existing design methods, CalME provides an Incremental-Recursive Mechanistic-Empirical (IRME) method in which the materials properties for the pavement are updated in terms of damage as the simulation of the pavement life progresses. The IRME design method incorporates various mathematical models to describe material behaviors and predict structure performances. These models need to be calibrated before they can be used to evaluate performance of different flexible pavement structures. This technical memorandum focuses on calibration of the incremental-recursive rutting model used in CalME when employing data collected during the APT (accelerated pavement testing) conducted in the first research cycle (years 2000–2002) at the NCAT (National Center for Asphalt Technology) pavement test track. It was found that the shift factor...

Updating Weigh-in-Motion (WIM) Spectra in PaveM

Fri, 28 Feb 2025 00:00:00 +0000

Weigh-in-motion (WIM) devices measure and record highway vehicle axle loads. The data they collect include axle loads and spacing, vehicle classification and gross weights, and travel speed. These WIM data are used for pavement design, management, and performance studies. In 2016, there were 123 WIM devices operating on sites throughout the California state-owned highway network, one of the densest and best maintained in the United States. The University of California Pavement Research Center (UCPRC) has studied California’s WIM data with the California Department of Transportation (Caltrans) since 2007 to advance mechanistic-empirical (ME) pavement design procedures. Previously, the UCPRC completed the first analysis of the WIM data collected from 1998 to 2003 to discover similarities in axle load distributions at the WIM sites and then grouped them using cluster analysis to generate default traffic inputs for pavement design software. For this research, the UCPRC processed WIM...

Development of Hot Mix Asphalt Pavement Performance Properties for Long-life Pavement Designs: Caltrans District 2, Interstate 5, Weed, California

Fri, 28 Feb 2025 00:00:00 +0000

In the period 2012 to 2014 Caltrans designed and built three long-life asphalt pavement (LLAP) rehabilitation projects. Two were in District 2 on Interstate 5 and one was in District 4 on Interstate 80. This technical memorandum describes the processes that were followed to develop the performance criteria for a pavement section to be designed and constructed as a long-life asphalt pavement (LLAP) section on Interstate 5 through and north of Weed, California. Appropriate layers of the structural pavement included 25 percent reclaimed asphalt (RAP), based on the availability of this material. Two designs were included in the development process. The planned structural pavement design included the following two hot mix asphalt mixes: An HMA surface course containing a polymer-modified asphalt (PG 64-28PM) and a representative aggregate from the Weed area treated with 1.2 percent lime (marinated) plus 15 percent RAP, and An HMA intermediate course containing a conventional asphalt...

Summary of a Computer Modeling Study to Understand the Performance Properties of Fully Permeable Pavements

Fri, 28 Feb 2025 00:00:00 +0000

This technical memo presents a summary of the methods and results from a computer modeling study, undertaken to understand the performance under loading of fully permeable pavements. Input data for the models was obtained from the comprehensive laboratory investigation undertaken as part of the study and from California Department of Transportation databases. The results presented in this tech memo will be used to prepare pavement designs for fully permeable pavement pilot studies in California and to identify under what conditions they are appropriate to use. The preliminary pavement designs will be presented in a separate report.

Sensitivity Analysis of 2002 Design Guide Rigid Pavement Distress Prediction Models

Fri, 28 Feb 2025 00:00:00 +0000

The AASHTO 2002 Design Guide (2002DG) has been calibrated using LTPP sections throughout the nation but with very few sections from the state of California. This created the need to validate the models in 2002DG and recalibrate them if needed so that they may be used for pavement design and rehabilitation in California. In order to validate the design guide, a three-stage process has been identified: bench testing or sensitivity analysis, verification using accelerated pavement testing data, and verification using field data. The study presented in this report includes performing sensitivity analysis of the rigid part of 2002DG.

Sensitivity analysis helps to check the reasonableness of the model predictions, to identify problems in the software, and to help understand the level of difficulty involved in obtaining the inputs. The reasonableness of the model predictions is checked by varying key design variables including traffic volume, axle load distribution, climate...

Life Cycle Assessment and Life Cycle Cost Analysis for Six Strategies for GHG Reduction in Caltrans Operations

Fri, 28 Feb 2025 00:00:00 +0000

California state government has established a series of mandated targets for reducing the greenhouse gas (GHG) emissions that contribute to climate change. With a multiplicity of emissions sources and economic sectors, it is clear that no single change the state can make will enable it to achieve the ambitious goals set by executive orders and legislation. Instead, many actors within the state’s economy—including state agencies such as the California Department of Transportation (Caltrans)—must make multiple changes to their own internal operations. The focus of this study and technical memorandum is to examine several strategic options that Caltrans could adopt to lower its GHG emissions in operating the California (CA) state highway network and other transportation assets so it can help meet the state’s GHG reduction goals. Although many GHG reduction strategies appear to be attractive, simple, and effective, most also have limitations, trade-offs, and unintended consequences...

Pavement ME JPCP Transverse Cracking Model Calibration and Design Catalog Framework (Version 2.5.5)

Fri, 28 Feb 2025 00:00:00 +0000

The Mechanistic-Empirical Pavement Design Guide (MEPDG) is a comprehensive method, including models and guidance, developed in 2002 by the American Association of State Highway and Transportation Officials (AASHTO) to analyze and design both flexible and rigid pavements. The MEPDG is implemented in a software called Pavement ME. The MEPDG models were calibrated using data from the Long-Term Pavement Performance (LTPP) sections from throughout the United States, including some from California. The MEPDG recommends that nationally calibrated models be validated using local data and, if necessary, recalibrated. This recommendation is particularly applicable to the Caltrans road network, considering the climate and materials differences between California and the rest of the nation. The first step in recalibrating Pavement ME is to perform a sensitivity analysis to identify which variables are most important and to look for results that do not match expected performance. This was...

Development of Performance-Based Specifications for Asphalt Rubber Binder: Phase 2g Testing of Plant-Sampled Binders and RHMA-G Mixes

Thu, 27 Feb 2025 00:00:00 +0000

The work discussed in this interim report is part of a larger study, funded by the California Department of Transportation. The study objective focuses on developing and recommending testing procedures and criteria for performance-based specifications of asphalt rubber binders used in gap-graded and open-graded mixes using current Superpave performance grade (PG) equipment. Work in this phase covered the testing of 19 plant-produced binders and the base binders used to produce them. Plant-produced gap-graded rubberized hot mix asphalt mixes from five of the projects were also tested. The following important observations from the binder rheology tests were made:

--Although the low-temperature performance grades appeared to be reasonable, the high-temperature grades appeared to be unrealistically high, while the intermediate-temperature grades appeared to be potentially lower than anticipated, when comparedto the base binders. Fourteen of the binders tested with concentric...

Use of Recycled Asphalt Pavement in Rubberized Hot Mix Asphalt—Gap-Graded

Fri, 31 Jan 2025 00:00:00 +0000

Current Caltrans Standard Specifications for rubberized hot mix asphalt–gap-graded (RHMA-G) do not allow the inclusion of reclaimed asphalt pavement (RAP). This report summarizes the research conducted by the UCPRC in support of the Caltrans-industry initiative “10% RAP in RHMA-G,” whose goal is to evaluate the use of up to 10% RAP (by aggregate replacement) in RHMA-G mixes, provided that the research does not identify significant potential problems for durability. Five pilot projects were built by Caltrans as part the initiative. In each of the pilots, a control RHMA-G (without RAP) and an RHMA-G with 10% RAP were placed. The mixes were sampled during production and tested using performance-related tests at the UCPRC laboratory. The results of the testing of the mixes—including stiffness, four-point bending fatigue resistance, and rutting resistance—indicate that the addition of 10% RAP had minor effects on the mechanical properties of the RHMA-G. With just a few exceptions related...

Analysis of Recycling Agent Effects on the Mechanical Properties of HMA with High Recycled Binder Ratios

Mon, 16 Dec 2024 00:00:00 +0000

The goal of the research presented in this report is to study how the mechanical properties of hot mix asphalt change upon the addition of high contents of reclaimed asphalt pavement (RAP) and the inclusion of any amount of recycled asphalt shingles (RAS), with between 25% and 50% binder replacement and to consider the addition of recycling agents to reduce the increase in stiffness and corresponding decrease in fatigue resistance. To achieve this goal, 16 mixes and the corresponding binders were fabricated and tested in the laboratory. The mix factorial includes a control gradation, two virgin binders (PG 64-16 and PG 58-28, from different sources), two RAPs with different levels of aging (PG high temperatures of 102°C and 109°C), one RAS, and two recycling agents (a petroleum-derived aromatic and a tall oil). The testing of the binders included performance grade (PG), shear stiffness, and Fourier transform infrared spectroscopy. The testing of the mixes included stiffness, four-point...

Rest Period Characteristics Under Highway Truck Traffic for Mechanistic-Empirical Designs of Asphalt Concrete Pavements

Tue, 10 Dec 2024 00:00:00 +0000

Fatigue cracking due to repeated truck traffic loads is the leading cause of failure of asphalt concrete pavement in many locations. Rest periods, referring to the time intervals between successive trucks, may allow for partial or full recovery from fatigue damage and in turn extend pavement fatigue life. This study examines the characteristics of rest periods using traffic data from 40 weigh-in-motion (WIM) stations installed on California state highways and evaluates their effects on pavement performance using a mechanistic-empirical simulation program, CalME. Truck traffic data were extracted from these WIM stations at selected periods throughout 2015. Rest periods, the probability distribution of rest periods, and quantiles of cumulative rest periods were calculated. Regression and statistical analyses of the 0.5 quantiles (i.e., median) of rest periods were also performed for different spectrum groups and seasons. It was found that rest periods are strongly correlated...

Twenty-Year Performance Review of Long-Life Jointed Plain Concrete Pavements

Wed, 4 Dec 2024 00:00:00 +0000

This technical memorandum evaluates the half-life performance of three long-life jointed plain concrete pavements (JPCPs), a combined total of 260 lane-miles, that were built in Southern California in the early 2000s. The pavements were designed for a 40-year life, which was twice the standard 20-year design life used for JPCP at that time. The projects are located in or close to the Mojave Desert on heavily trafficked interstate highways with 2022 annual average daily truck traffic levels between 2,800 to 5,100. The performance of the pavements has been evaluated based on data from the Caltrans pavement management system (PMS) databases (with software system PaveM), including pavement condition surveys with data about lane-based cracking, transverse joint faulting, and smoothness data, and the as-built database that includes all maintenance, rehabilitation, and reconstruction activities conducted on the Caltrans road network. The PMS databases were complemented with an in-situ...

Identification of Likely Alternative Supplementary Cementitious Materials in California: A Review of Supplies, Technical Performance in Concrete, Economic, and Climatic Considerations

Sun, 22 Sep 2024 00:00:00 +0000

This report is a comprehensive review of natural and human-made materials with the potential to reduce cement content in concrete by partially replacing portland cement or as additives. The review aims to reveal possible source materials as alternative supplementary cementitious materials (ASCMs) to coal-burned fly ash and ground granulated blast furnace slag as these SCMs supplies rapidly decline. Information required to estimate supplies of each ASCM was gathered, and ASCM candidates with enough abundance to support California’s concrete paving sector were identified for further laboratory evaluation. In addition, the required chemical, thermal, and mechanical treatments of the source materials were gathered so the environmental and economic impacts of the processes could be considered. A review of scientific literature on the technical performance of the studied materials in cement paste, mortar, or concrete was also conducted when that information was available.

The...

Life Cycle Cost Analysis Input Framework for Full Depth Recycling and Application on State Route 113 and State Route 84

Fri, 26 Apr 2024 00:00:00 +0000

Full depth recycling (FDR) has emerged as a feasible rehabilitation alternative in California. This study focuses on addressing the economic feasibility of example FDR structures using life cycle cost analysis (LCCA) that included probabilistic and deterministic life cycle agency costs and deterministic life cycle road user costs. Two LCCA case studies were performed to provide an initial understanding of the agency cost variation. Estimating roadway construction costs plays a key role in pavement LCCA and long-term planning. Materials costs per functional unit are the major input values affecting pavement cost and total construction cost, and they are dependent on project scale, market, region, risk, climate, and economic circumstances. Publicly available contract cost data from past roadway construction activities on the California state highway network were used in this study. Economies of scale suggest that high quantities of materials would have lower unit costs. Unsupervised...

Pavement Recycling: Shrinkage Crack Mitigation in Cement-Treated Pavement Layers—Phase 2b Laboratory Testing and Performance Modeling

Fri, 26 Apr 2024 00:00:00 +0000

The California Department of Transportation (Caltrans) has been using full-depth recycling (FDR) as a pavement rehabilitation strategy since 2001. Early projects were recycled with foamed asphalt and cement. Cement-only treatments were permitted from 2015 to improve the properties of more marginal materials. However, shrinkage cracking associated with the hydration and curing of the cement-treated layers remains a concern, especially with regard to crack reflection through asphalt concrete surfacings and the related problems caused by water ingress.Crack mitigation has been studied for decades, and a range of measures related to improved mix designs and construction practices have been implemented by road agencies. One of the most promising measures, used in conjunction with appropriate mix designs, is that of microcracking the cement-treated layer between 48 and 72 hours after construction. In theory, this action creates a fine network of cracks in the layer that limit or prevent...

Drying Shrinkage Response of Full-Scale Thin Concrete Overlay on Asphalt Sections

Thu, 28 Mar 2024 00:00:00 +0000

Moisture-related shrinkage is regarded as one of the phenomena that has the largest impacts on the performance of jointed plainconcrete pavements. Still, most mechanistic-empirical design methods oversimplify or ignore predictions of moisture-relatedshrinkage and its effects on concrete pavements. This study evaluates how moisture-related shrinkage accumulates in concretepavements and the structural response of the concrete pavement slabs to the shrinkage action. The experimental data comefrom six thin concrete overlay of asphalt pavements that were instrumented with sensors to measure the structural andhygrothermal response of the slabs due to temperature and moisture-related actions. After an analysis of the predictions madeby current shrinkage models, a new shrinkage model was developed. This new model, which is based on the incremental-recursive application of the B4 shrinkage model, provided an excellent prediction of the moisture-related shrinkage measured inthe field. In...

Thin Concrete Overlay on Asphalt Pilot Project at Woodland SR 113: Initial Performance

Mon, 27 Nov 2023 00:00:00 +0000

This report presents the initial performance of the Woodland SR 113 thin concrete overlay on asphalt (COA) project built in 2018-2019.The project comprises approximately four miles of a two-lane highway. The COA had 6 ft. transverse joint spacing, a slab thickness of 6in., and an asphalt base that was overall in very poor condition. The performance of the project between the date of construction andOctober 2020 is presented in this report. The performance was evaluated by different means, including periodic visual inspections andlongitudinal profiler evaluations; falling weight deflectometer (FWD) testing; real load testing (RLT), where the concrete strains undertruck loading were recorded; and continuous monitoring of slab temperatures and drying shrinkage deformations. Overall, the projectperformed as expected. Visual inspection of the COA did not indicate any cracking, faulting, or other structural distress. FWD and RLTevaluations indicate that the COA structure has remained...

Preliminary Study on Developing a Surrogate Performance-Related Test for Fatigue Cracking of Asphalt Pavements

Tue, 18 Jul 2023 00:00:00 +0000

Currently, no performance-related test exists for fatigue cracking for use in routine asphalt mix design to approve job mix formula (JMF) and quality control and quality assurance (QC/QA) in California. The existing four-point bending (4PB) test was developed to evaluate the fatigue performance of asphalt pavement, but it is not necessarily appropriate for use in routine JMF and it is too slow for QC/QA. The objective of this study is to evaluate potential surrogate fatigue performance-related testing methods and identify a test that is simple and easy to perform but also able to provide guidance for asphalt mix design on routine projects and QC/QA on all projects. This report compares potential performance-related tests with 4PB tests for simplicity, repeatability (variability), and their relationship to stiffness and fatigue life. Tests evaluated in this study included the semicircular bend (SCB) test, indirect tensile asphalt cracking test (IDEAL-CT), and fatigue testing on...

Development of Performance-Based Specifications for Asphalt Rubber Binder: Interim Report on Phase 1 and Phase 2 Testing

Sun, 16 Jul 2023 00:00:00 +0000

In the United States, the Superpave Asphalt Binder Performance Grading (PG) system proposed by the Strategic Highway Research Program (SHRP) is the most common method used to characterize the performance-related properties of unmodified and polymer-modified asphalt binders. Dynamic shear modulus (G*) and phase angle (δ) are the two main binder properties and they are measured using a dynamic shear rheometer (DSR) with parallel plate geometry and either a 1-mm or 2-mm gap between the plates. Since these Superpave parameters were developed for binders that do not contain additives or particulates, the California Department of Transportation (Caltrans) does not use them for asphalt rubber binder specifications. Instead, penetration and viscosity are used as acceptance of quality control; however, these parameters do not necessarily provide a satisfactory link between the measured binder properties and potential performance in the field over a range of operating temperatures. In California,...

Smoothness Monitoring of Selected Concrete Surfaces

Mon, 10 Jul 2023 00:00:00 +0000

In late 2015, Caltrans requested that 26 recently constructed concrete projects be tested for smoothness in terms of the International Roughness Index (IRI). The stated purpose was to observe measured IRI on projects accepted after a standard special provision (SSP) change that Caltrans made in 2013 and that was incorporated into the 2015 Construction Contract Standards. The projects provided 52 test sections for evaluation, consisting of three types of paving work: (1) diamond grind on existing pavement, (2) new continuously reinforced concrete pavement, and (3) new jointed plain concrete pavement. The project plans had completion dates from May 2010 to December 2014, and contract acceptance dates from April 2014 to October 2015. Caltrans did not identify which projects had the new SSP or specification change in its contract documents. The IRI data were collected from October 2016 to December of 2016. The IRI data collected included the effects of paving, any corrective grinding...

Cold Central Plant Recycling Study: Test Track Construction, Layout, and Instrumentation

Mon, 26 Jun 2023 00:00:00 +0000

This technical memorandum summarizes the construction and instrumentation of a test track to study the behavior of cold central plant recycled (CCPR) layers in a pavement structure. Two recycling agents will be tested including emulsified asphalt from two different producers and foamed asphalt from one binder supplier. The pavement structure includes an aggregate subbase, an aggregate base, the recycled layer, and a gap-graded rubberized hot mix asphalt (RHMA-G) surfacing. The structure was constructed on prepared subgrade. Material properties and construction procedures met all relevant Caltrans specifications. Instrumentation includes multi-depth deflectometers, strain gauges, pressure cells, and moisture sensors. The test track was considered to be representative of a highway project and was approved for Heavy Vehicle Simulator testing.

First-Level Analysis of Phase 1 Heavy Vehicle Simulator and Laboratory Testing on Four RHMA-G Mixes to Investigate Nominal Maximum Aggregate Size, Layer Thickness, and Performance with Aggregate Replacement from Reclaimed Asphalt Pavement

Thu, 15 Jun 2023 00:00:00 +0000

This research report summarizes a literature review update, construction of a test track to assess various aspects of gap-graded rubberized asphalt concrete (RHMA-G) mixes with and without the addition of reclaimed asphalt pavement (RAP) as aggregate replacement, a first-level analysis of the results from five Heavy Vehicle Simulator (HVS) tests, and a first-level analysis of laboratory test results on the four mixes.

Four different RHMA-G mixes were placed on seven cells on the test track at the UCPRC. Mixes differed by nominal maximum aggregate size (NMAS, 1/2 and 3/4 in.) and the addition of 10% RAP by weight of the aggregate as an aggregate replacement. Single and double lifts of each mix were placed. Apart from the addition of RAP, the mix designs all met current Caltrans specifications. Although Caltrans currently does not permit more than one lift of RHMA-G on projects, the placement of each lift of each mix on the test track met current Caltrans specifications...

Development of Performance-Based Specifications for Asphalt Rubber Binder: Phase 2g Additional Testing of Five Plant-Sampled Binders and RHMA G Mixes

Thu, 15 Jun 2023 00:00:00 +0000

The work discussed in this interim report is part of a larger study, funded by the California Department of Transportation, with the objective of developing and recommending testing procedures and criteria for performance-based specifications of asphalt rubber binders used in gap-graded and open-graded mixes using current Superpave performance grade (PG) equipment. Work covered the testing of five plant-produced binders, the base binders used to produce them, and the gap-graded rubberized hot mix asphalt mixes produced with them. The following important observations from the binder rheology tests were made:

Although the low-temperature performance grades appeared to be reasonable, the high-temperature grades appeared to be unrealistically high, while the intermediate-temperature grades appeared to be potentially lower than anticipated when compared to the base binders. A comparison of the concentric cylinder and parallel plate (3 mm gap) geometries indicated that the...

RAP and RAS in HMA Pilot Project on ELD 49: Material Testing, Observations, and Findings

Mon, 5 Jun 2023 00:00:00 +0000

A pilot project for the inclusion of recycled asphalt shingles (RAS) in hot mix asphalt (HMA) was built on State Route 49 in El Dorado County in November 2021. Four mixes were included in short test sections: (1) a control mix with no RAS or recycled asphalt pavement (RAP), (2) a typically used mix with 10% RAP that was also used for construction of the rest of the overall project, (3) a mix with 3% RAS, and (4) a mix with 10% RAP and 3% RAS. This technical memorandum presents the laboratory test results from plant mix produced for job mix formula (JMF) verification and from two quality assurance (QA) samples taken during test section construction as well as observations of plant production and construction. The results showed that the mixes submitted for JMF verification and tested as part of QA all met the two performance-related specifications. Most of the QA samples had binder and mix testing results that were similar to or better than those of the JMF verification samples,...

Framework and Demonstration of Simulations of Environmental Impacts from Traffic on Highway Construction Work Zones

Fri, 21 Apr 2023 00:00:00 +0000

The objective of this study was to develop a framework for determining the fuel use and environmental impacts caused by construction work zones (CWZs) on a range of vehicles and to produce initial calculations of these impacts by modeling traffic closure conditions for highway maintenance and rehabilitation (M&R) activities. The framework was developed and demonstrated in several scenarios. The study included three common highway categories—freeways, multi-lane highways, and two-lane highways—and common California vehicle types. The framework uses realistic drive cycle values and CWZ operation scenarios as inputs to the simulation software MOtor Vehicle Emission Simulator (MOVES) to estimate total fuel consumption and air pollutant emissions. In this study, the framework was demonstrated using three CWZ operations under different traffic congestion levels: light, medium, and heavy.

Fuel consumption and pollutant emissions results obtained for the CWZ operation scenario...

Water Quality and Toxicity Evaluation of Discharge Generated from Asphalt Pavement Surfacing Materials

Mon, 17 Oct 2022 00:00:00 +0000

Pavement engineers are constantly using new materials, such as polymer and rubber modified binders, recycled materials, and new types of asphalt mixes, such as open-graded surface courses. With their broader application, concern has been raised about the water quality of surface and subsurface runoff from modified pavement mixes used in the State of California. There are limitations in current worldwide research into runoff water quality regarding which contaminants are directly attributable to the pavement surfacing materials. This research project aims to provide that information, as part of ongoing stormwater runoff management program from the Division of Environmental Analysis of the State of California Department of Transportation (Department).

This controlled experimental study was undertaken by the Department of Civil and Environmental Engineering and the University of California Pavement Research Center (UCPRC) for the California Department of Transportation (Caltrans),...

Development of Caltrans Concrete Overlay on Asphalt Pavement Design Catalog Tables Using Pavement ME

Fri, 16 Sep 2022 00:00:00 +0000

This report summarizes the work completed to develop the concrete overlay on asphalt (COA) tables of the new Caltrans Highway Design Manual (HDM) Rigid Pavement Design Catalog. The tables consider the different pavement structures that are candidates for rehabilitation with COA with short transverse joint spacing on the Caltrans road network. The tables were developed using Pavement ME (version 2.5.5) with the nationally calibrated COA cracking model. Pavement ME inputs were determined by considering the state’s climate, traffic, materials, and construction practices. The design tables reflect the recommendations from previous Caltrans research about COA, including slab size, shoulder type, and load transfer efficiency. The Pavement ME inputs for developing the tables include a design life of 20 years, 10% target cracking, and 95% design reliability. The tables will be included in the printed version of the new HDM Rigid Pavement Design Catalog.

Development of Caltrans Jointed Plain Concrete Pavement Design Catalog Tables Using Pavement ME

Thu, 1 Sep 2022 00:00:00 +0000

This report summarizes the work conducted to develop the jointed plain concrete pavement (JPCP) tables of the new Caltrans HighwayDesign Manual (HDM) Rigid Pavement Design Catalog. The tables consider the different pavement structures that are expected toperform properly on the Caltrans road network. The tables were developed using Pavement ME (version 2.5.5) with the nationallycalibrated transverse cracking model. Pavement ME inputs were determined by considering the state’s climate, traffic, materials, andconstruction practices. A design life of 40 years, 10% target transverse cracking, and 95% design reliability were chosen for developmentof the tables. Transverse joint faulting and the International Roughness Index (IRI) were also determined for the sections in the JPCPtables using Pavement ME (version 2.5.5) nationally calibrated models and compared to Caltrans faulting and IRI limits of 0.15 in. and170 in./mi., respectively. The tables will be included in the printed version...

Pavement Life Cycle Inventories for California: Models and Data Development in the Last Decade for Caltrans

Tue, 28 Jun 2022 00:00:00 +0000

Pavement Life Cycle Inventories for California: Models and Data Development in the Last Decade for Caltrans

Site Investigation Guide for Mechanistic-Empirical Design of California Pavements

Tue, 28 Jun 2022 00:00:00 +0000

This document provides guidance on conducting site investigations for new highway construction and widening, rehabilitation, and reconstruction of existing roads. Site investigation is an important part of the pavement design process. This guide has been developed as an integral part of the mechanistic-empirical pavement design procedures for new pavement and rehabilitation and reconstruction of existing pavement. An investigation requires four steps: (1) the preliminary site investigation and desktop data collection, (2) the detailed site investigation and data collection for design, (3) the site investigation data analysis, and (4) the project investigation report.

Pavement Recycling: Shrinkage Crack Mitigation in Cement-Treated Pavement Layers — Phase 2a Literature Review and FDR-C Test Road Construction and Monitoring

Fri, 18 Mar 2022 00:00:00 +0000

The California Department of Transportation has been using full-depth recycling (FDR) as a rehabilitation strategy since 2001. Early projects were recycled with foamed asphalt and cement, but cement-only treatments were permitted from 2015 to improve the properties of more marginal materials. However, shrinkage cracking associated with the hydration and curing of the cement-treated layers remains a concern, especially with regard to crack reflection through asphalt concrete surfacings and the related problems caused by water ingress.

Considerable research has been undertaken on crack mitigation, and a range of measures related to improved mix designs and construction practices have been implemented by road agencies. One of the most promising measures, used in conjunction with appropriate mix designs, is that of microcracking the cement-treated layer between 24 and 72 hours after construction. In theory, this action creates a fine network of cracks in the layer that limit...

Investigation of the Effect of Pavement Deflection on Vehicle Fuel Consumption: Field Testing and Empirical Analysis

Tue, 15 Mar 2022 00:00:00 +0000

The results presented in this report are part of Phase II of a two-phase study. Based on the results from mechanistic models of additional fuel consumption in vehicles due to the structural response of the pavement structure, Phase I of this study concluded that pavement has a small but important enough effect on vehicle fuel consumption to warrant field investigation. The goal of the Phase II study was to measure vehicle fuel consumption in the field on different pavement types in winter and summer and at different speeds, and to use the data collected to develop empirical models for this fuel-consumption effect. The field investigation presented in this report included 21 California pavement sections with different pavement types: flexible, semi-rigid, jointed plain concrete, continuously reinforced concrete, and composite structures. The vehicles selected and instrumented for the fuel economy measurements included a five-axle semi-trailer tractor, a diesel truck, a sports utility...

Pavement ME Sensitivity Analysis (Version 2.5.3)

Tue, 15 Mar 2022 00:00:00 +0000

The Mechanistic-Empirical Pavement Design Guide (MEPDG) is a comprehensive tool developed in 2002 by the American Association of State Highway and Transportation Officials (AASHTO) to analyze and design both flexible and rigid pavements. The models in the MEPDG are implemented in software called Pavement ME, a program calibrated using Long-Term Pavement Performance (LTPP) sections from throughout the United States, including some from California. The MEPDG recommends that nationally calibrated models be validated using local data, and if necessary, recalibrated, which makes sense when considering the climate and materials differences between California and the rest of the nation. The first step in recalibrating Pavement ME is to perform a sensitivity analysis to identify which variables are most important and to look for results that do not match expected performance. The factorial for the sensitivity analysis was designed to identify sensitivity and is not the factorial to be...

Lessons Learned from Caltrans Pilot Program for Implementation of EPDs

Tue, 1 Mar 2022 00:00:00 +0000

An environmental product declaration (EPD) is a transparent, verified report used to communicate the environmental impacts (e.g., resource use, energy, emissions) associated with the manufacture or production of construction materials such as asphalt, cement, asphalt mixtures, concrete mixtures, or steel reinforcement. EPDs, which are also called Type III Environmental Declarations, are product labels developed by industry in accordance with International Organization for Standardization standards. The scoping document for an EPD, which is also referred to as a product category rule (PCR), defines the requirements for EPDs for a certain product category. Beginning in 2019, Caltrans initiated a pilot study requiring EPDs for hot mix asphalt, aggregates, and concrete in addition to the materials specified by the Buy Clean California Act (BCCA) (Assembly Bill 262). The requirement to submit EPDs for these materials is how plans made several years prior to passage of the BCCA, for...

Concrete Overlay on Asphalt Pilot Project at Woodland SR 113: Construction

Wed, 16 Feb 2022 00:00:00 +0000

This report documents the design and construction of a concrete overlay on asphalt (COA) pavement on State Route 113 in Woodland, California, one of the first COA projects in the Caltrans road network. The project site extended over approximately 4 mi. of a two-lane secondary road. The concrete slabs were a half-lane wide (6×6 ft.) and 6 in. thick. The transverse joints were undoweled, but tie bars were installed at all the longitudinal joints. The outside slabs were 2 ft. wider than the interior slabs to provide a concrete shoulder. The project included a section with newly placed, rubberized, gap-graded asphalt mix base. A rapid-strength concrete mixture with Type II/V portland cement designed to be opened to traffic in 24 hours was used for construction of the overlay. The northern part of the project (PM 14.760 to PM 17.580) was built in October and November 2018, while the southern part (PM 11.860 to PM 12.890) was built in April and May 2019. The concrete mixture was produced...

Increasing Crumb Rubber Usage by Adding Small Amounts of Crumb Rubber Modifier in Hot-Mix Asphalt. Phase 1: Laboratory Tests and CalME Simulations

Wed, 16 Feb 2022 00:00:00 +0000

In 2015, Caltrans expressed interest in studying the addition of small amounts of crumb rubber (CRM) in dense-graded asphalt mixes toincrease the total amount of recycled tire rubber used. Small amounts were defined as 5% to 10% CRM by weight of the binder orapproximately 0.25% to 0.5% CRM by weight of the aggregate. In this report, the terms “CRM binder” and “CRM mix” are used todenote the modified mixes. Four approaches for adding the rubber were proposed: 1) Addition of 5% to 10% CRM particles smaller than250 μm to the asphalt binder, not resulting in a change to the PG of the base binder, achieved by blending softer base binders and/orpolymers with the rubber at the refinery/terminal; 2) Addition of 5% to 10% CRM particles smaller than 2.36 mm to the asphalt binder,with allowable changes to the PG of the base binder, and produced using a field-blending process similar to that used for producingasphalt rubber binders with between 18% and 22% CRM; 3) Adding 0.25% to 0.5%...

eLCAP: A Web Application for Environmental Life Cycle Assessment for Pavements

Fri, 11 Feb 2022 00:00:00 +0000

The California Department of Transportation (Caltrans) has a growing need to be able to quantify its greenhouse gas (GHG) emissions and the other environmental impacts of pavement operations, and to consider GHG and those other impacts in pavement management, conceptual design, design, materials selection, and construction project delivery decisions. Caltrans also needs to be able to evaluate the life cycle environmental impacts as part of policy and standards development. All these tasks can be performed using life cycle assessment (LCA), although there are different constraints and requirements with respect to the scope of the LCA and the data available for each of these different applications. The web-based software environmental Life Cycle Assessment for Pavements (eLCAP) is a project-level LCA tool that uses California- and Caltrans-specific life cycle inventories (LCIs) and processes. The LCI database has been critically reviewed by outside experts following ISO standards....

Pavement ME Evaluation of the NCHRP 1-61 Thin Concrete Overlay on Asphalt Sections

Fri, 11 Feb 2022 00:00:00 +0000

The thin concrete overlay on asphalt (COA) longitudinal cracking model of Pavement ME was calibrated with empirical data from COA sections with half-lane width slabs in Minnesota, Illinois, and Colorado. The NCHRP Project 1-61 has considerably expanded the range of climatic conditions for which reliable performance data are available by adding projects from Iowa, Kansas, and Philadelphia (in addition to Minnesota, Illinois, and Colorado). This technical memorandum assesses Pavement ME predictions based on the longitudinal cracking measured on 13 COA sections with half-lane width slabs evaluated as part of NCHRP Project 1-61. None of the 13 sections had more than 3% of slabs with longitudinal cracking, despite four of them being subjected to relatively high traffic volumes (annual average daily truck traffic over 500 vehicles on the design lane) and having been in service between 9 and 19 years. When design values were adopted for the different input variables, Pavement ME predicted...

eLCAP: A Web Application for Environmental Life Cycle Assessment for Pavements

Wed, 9 Feb 2022 00:00:00 +0000