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

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

(2022)

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.

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

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

(2022)

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 of the new HDM Rigid Pavement Design Catalog.

  • 1 supplemental PDF
Cover page of Continued Noise and Smoothness Monitoring on Concrete Pilot Projects of Grind and Groove and Continuously Reinforced Concrete Pavements

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

(2022)

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 policy and specifications. This report presents the results of testingcompleted in 2016 and 2017 on sections first tested in 2012 and 2013. Recommendations include continued monitoring of GnG,considering use on CRCP, and continued use of diamond grinding. Additional testing will be performed between 2017 and 2020.

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

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

(2022)

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 less than 5% longitudinal cracking in 12 of the 13 sections, which agrees with measured cracking. The root mean square error (RMSE) of Pavement ME predictions was 2.4% for the set of 13 sections. The RMSE of the Pavement ME predictions improved to 1.2% when constructed slab thickness measured with ground penetration radar was used instead of the design thickness. However, Pavement ME predictions did not improve when measured values for concrete strength or load transfer efficiency were used rather than design values. The recommendation is that the nationally calibrated COA cracking model, implemented in Pavement ME version 2.5.5 (the current version as of the writing of this technical memorandum), be used for developing the California COA design catalog.

Cover page of 2021 Cold Recycling Pilot Projects: Construction and Quality Control

2021 Cold Recycling Pilot Projects: Construction and Quality Control

(2022)

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 of the road to accommodate the materials without changing grade height.• There was no discernable difference in the density and strengths of PDR layers produced with the single- and multi-unit trains. The main benefit of the multi-unit train is better control of maximum aggregate size by the on-board screens and crushing unit. However, the crushing unit does not appear to change or improve the finer portion of the gradation (i.e., material passing the #4 [4.75 mm] sieve), which will have a larger influence on compaction density, air-void content, strength, and moisture resistance.• On coarse gradations, higher foamed asphalt contents were required to achieve the minimum indirect tensile strength requirement compared to emulsified asphalt. This is attributed in part to the coating action provided by emulsion treatments being more effective than the “spot welding” action provided by foam treatments on coarse, high air-void content gradations.• Marshall compaction overestimated the in-place density of PDR layers to a greater extent than gyratory compaction.• Rerolling can result in a small increase in density on PDR-EA layers. The timing of rerolling will influence the extent of this increase.• The densities recorded on specimens produced for strength and stability tests were not always consistent with the density results measured on the layer. This difference was attributed in part to inherent variability in the materials and pavement structure, sampling and handling procedures, and different specimen preparation procedures used by the contractors.• Relationships between gradations of field samples and field densities were inconsistent, which was also attributed to inherent variability in the materials that may not be captured in the small samples taken to represent a relatively large area of the layer.The pilot projects should be monitored to evaluate long-term performance. Monitoring should include annual visual surveys, annual or biannual falling weight deflectometer testing, and biannual coring and dynamic cone penetrometer testing. This study has highlighted a number of issues and suggested changes within the PDR mix design and quality control procedures followed in these projects (CT 315), which have been discussed with the method owner.

Cover page of eLCAP: A Web Application for Environmental Life Cycle Assessment for Pavements

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

(2022)

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. eLCAP models the life cycle history of a pavement project by allowing a user to specify any number of construction-type events, occurring at a user-specified date, followed by an automatically generated Use Stage event that begins immediately afterward and lasts until the next construction-type event or the end-of-life date. The Use Stage models currently consider the effects of roughness in terms of International Roughness Index and use the same performance models that are used in the Caltrans pavement asset management system software, PaveM. eLCAP performs a formal mass-balancing procedure on a pavement LCA project model and then computes 18 different impact category values—including Global Warming Potential, Human Health Particulate Air, Acidification, and different forms of Primary Energy—and generates a detailed Excel report file to display graphs and tables of results. The results can be presented in terms of life cycle stage, material types, and other details.

  • 1 supplemental PDF
Cover page of Investigation of the Effect of Pavement Deflection on Vehicle Fuel Consumption: Field Testing and Empirical Analysis

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

(2022)

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 vehicle (SUV), a gasoline-fueled car, and a diesel-fueled car. Vehicles were run on cruise control and data were recorded at 45 and 55 mph on state roads and at 35 and 45 mph on local roads. The data from the field investigation were analyzed and used to develop an empirical modeling framework considering road geometry, wind, temperature, and pavement structural and surface (roughness and texture) effects on vehicle fuel consumption. Based on the final framework, a final empirical model was developed for each section. The report presents results of a factorial analysis of the effects of each variable using the final model for each vehicle type on each pavement type and in different California climate regions. The within-section variability is almost always greater than the variability between sections for a given pavement type and efficiency condition (tailwind, speed, and climate region) and the within-section variability is also usually larger than the variability between pavement types. Only the data for the heavy heavy-duty truck (HHDT) showed any meaningful difference in results between sections, but that variability is not tied to pavement type and is only present under certain conditions of speed, tailwind, and air temperature (tied to climate region). These results indicate that missing variables (or errors in the existing variables) need to be reduced in further experiments to observe measurable effects of pavements on fuel consumption in real-world driving. While air temperature interacted with cruise control speed for the HHDT, there was a lack of clear evidence that asphalt roads cause more fuel consumption for the HHDT even under the conditions where the most possible effect of pavement type was found. This suggests that pavement type is not the correct explanation for that variation. Instead, the variation in the effect of air temperature by cruise control speed for the HHDT likely has to do with differences in engine efficiency under different conditions.

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

(2022)

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. eLCAP models the life cycle history of a pavement project by allowing a user to specify any number of construction-type events, occurring at a user-specified date, followed by an automatically generated Use Stage event that begins immediately afterward and lasts until the next construction-type event or the end-of-life date. The Use Stage models currently consider the effects of roughness in terms of International Roughness Index and use the same performance models that are used in the Caltrans pavement asset management system software, PaveM. eLCAP performs a formal mass-balancing procedure on a pavement LCA project model and then computes 18 different impact category values—including Global Warming Potential, Human Health Particulate Air, Acidification, and different forms of Primary Energy—and generates a detailed Excel report file to display graphs and tables of results. The results can be presented in terms of life cycle stage, material types, and other details.

  • 1 supplemental PDF
Cover page of Lessons Learned from Caltrans Pilot Program for Implementation of EPDs

Lessons Learned from Caltrans Pilot Program for Implementation of EPDs

(2021)

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 use of EPDs to help achieve environmental goals, are being implemented. While the BCCA considers only the greenhouse gas emissions contributing to global warming, the Caltrans pilot program for pavement and bridge materials also looks for other emissions in the EPDs, primarily emissions that cause air pollution. This project consisted of the University of California Pavement Research Center reviewing and helping develop Caltrans’s plans for collecting EPDs, reviewing PCRs and EPDs for consistency and inconsistencies, helping to communicate strategy with industries and the Federal Highway Administration, supporting Caltrans’s development of a web-based portal for entry of EPD data and the underlying database, and writing of a summary report. This technical memorandum is the summary report. This report documents the roadmaps developed for collecting and using EPDs, other support activities for the Caltrans EPD program, and a review of the EPDs supplied to Caltrans as of the summer of 2020 and their underlying PCRs. The PCRs for the materials in the Caltrans EPD program have inconsistencies that should be relatively simple to resolve with direction from Caltrans. In their current form, consistent data entry is difficult in the Caltrans EPD portal. To improve the consistency and quality of EPDs, Caltrans staff must receive guidance on how to review EPDs, and staff at materials producers require training about how to interpret PCRs to produce EPDs. Systems for inputting data from EPDs into department of transportation (DOT) reporting systems that include data quality checks, system consistency, and certification are also needed. Similarly, a nationally accepted and adopted data quality assessment standard is needed for EPDs as DOTs move toward their use in procurement. A single data quality matrix should also be included in a harmonized PCR.