University of California Pavement Research Center

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.

This document has been prepared to guide practitioners on project investigation, recycling strategy selection, pavement structural design, environmental life cycle and life cycle cost assessment, mix design, and construction of in-place pavement recycling projects on flexible pavements in California. It provides information specific to California conditions to supplement the California Highway Design Manual (HDM), specification documents, and other available design guides.

The main changes and updates to the 2017 version of the guide (UCPRC-GL-2017-04) include the following:

• Updates to terminology used for in-place recycling

• Updates to the project investigation chapter, including alignment with the new Caltrans site investigation guide, which was under review at the time of writing this guide

• Updates throughout the guide to include cold central plant recycling (CCPR) • Inclusion of mechanistic-empirical design procedures (CalME) in the design chapter • Updates to the mix design chapter to align with the new California Test Method (CT-315) for mix design for partial depth recycling

• Inclusion of a provisional laboratory procedure for mix designs for full-depth recycling with cement (FDR-C)

• Updates to the construction chapter to align with recent specification changes

Unacceptable levels of dust, poor riding quality, impassability in wet weather, and unsustainable maintenance and gravel replacement practices are experienced on most unpaved road networks, and although it is acknowledged that unpaved roads are fundamental to local, regional, and national economies, many current management practices used on these roads leave much to be desired. Over the past 100 years a range of chemical treatments has been developed to fill the need for reducing the environmental and social impacts of road dust, improving the performance and safety of unpaved roads, and/or improving the properties of marginal materials to the extent that a road can be given all-weather status or upgraded to a paved standard. Most of these chemical treatments are proprietary and there is often little documented information regarding the chemistry of the treatment, the results of experimental trials to determine under what conditions the chemical treatment will work best, or guidelines on where and how to use the treatment. Most unpaved road chemical treatments carry no formal specification nor do they adhere to formal environmental testing requirements. Consequently, there has been no large-scale effort to establish and/or implement formal unpaved road chemical treatment programs anywhere in the world, other than those used in site-specific industrial applications such as mining operations. This guide introduces a new process for selecting an appropriate chemical treatment category for a specific set of unpaved road conditions using ranked potential performance. The process is based on the practitioner setting an objective for initiating a chemical treatment program and understanding the road in terms of materials, traffic, climate, and geometry. Using the information collected, the most appropriate chemical treatment subcategories for a given situation can be selected from a series of charts and ranked using a simple equation. This process can be completed manually using a paper form, or by using a web-based (www.ucprc.ucdavis.edu) or spreadsheet tool. Matrices for each of the objectives were developed based on documented field experiments and the experience of a panel of practitioners. Guidance on specification language for procuring and applying unpaved road chemical treatments is also provided, along with comprehensive guidance on understanding unpaved road wearing course material performance.

This document provides guidelines on subgrade soil stabilization and covers mechanical, cementitious, and asphalt methods. The following aspects are discussed: An overview of subgrade stabilization methods, Project investigation, Mechanical stabilization, Cementitious stabilization, Asphalt stabilization, Construction considerations A list of further reading is provided.

This document provides guidelines on full-depth reclamation using a combination of foamed asphalt and an active filler, typically portland cement or lime. The following aspects are discussed: Project selection, Mix design, Structural design, Construction. The references provide a list of other commonly used guidelines.

This document provides guidelines for the establishment, monitoring and reporting of pavement preservation experiments in California. Information is provided in chapters covering: Management and responsibilities, Project fundamentals, Experiment work plan, Site selection, Experiment construction, Experiment monitoring, Forensic investigations, Laboratory testing, Data analysis, reports and implementation, Data management and documentation, Example experiment work plans, checklists and form. The document aims to assist with achieving successful completion of experiments and implementation of the findings.

This document provides guidelines for the establishment, monitoring and reporting of pavement preservation experiments in California. Information is provided in chapters covering: Management and responsibilities, Project fundamentals, Experiment work plan, Site selection, Experiment construction, Experiment monitoring, Forensic investigations, Laboratory testing, Data analysis, reports and implementation, Data management and documentation, Example experiment work plans, checklists and forms The document aims to assist with achieving successful completion of experiments and implementation of the findings.