Project snapshot. More details below.
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Products
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Impact on Practice
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Product Status
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COMPOSITE PAVEMENT SYSTEMS (R21)
Guidelines, validated models, techniques, and specifications for using two composite pavement systems: a thin, high-quality hot-mix asphalt layer over a Portland cement concrete (PCC) structural layer; and a thin, superior PCC surface over a second, less-expensive, recycled PCC layer. Guidelines include practical recommendations for construction specifications and techniques, life-cycle costing, quality management procedures, and training materials. Revisions to AASHTO MEPDG software and to the Manual of Practice.
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Composite pavements have delivered longer service life with excellent surface characteristics and structural capacity, while being economical and sustainable. But objective studies of their use and installation have been inadequate to support widespread adoption. This project conducted the validation and produced needed documentation so that transportation agencies can have confidence that the composite pavement systems they install and maintain will be long-lasting and have predictably low life-cycle costs.
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Staff Responsibility: James Bryant
Composite pavements have been proven in Europe and in the United States to have long service life with excellent surface characteristics, structural capacity, and rapid renewal when needed. Composite pavements also reflect the current direction of many highway agencies to build economical, sustainable pavement structures that use recycled materials and locally available materials. However, while many transportation agencies may have performance data and models for conventional pavement systems, the behavior of new composite pavements is not well understood. Models for the performance of these hybrid systems are needed for design, performance prediction, and life-cycle cost analysis. Guidance on specifications, construction techniques, and quality management procedures are also needed.
The objective of this project was to investigate the design and construction of new composite pavement systems, but not those resulting from the rehabilitation of existing pavements. The research focused on two promising applications of composite pavement systems: (1) an asphalt layer(s) over a PCC layer and (2) a PCC surface over a PCC layer.
This project determined the behavior, material properties, and performance for each type of composite pavement under many climate and traffic conditions. Experimental composite pavements were constructed at MnROAD in Minnesota and University of California Pavement Research Center at Davis, where the pavements were instrumented and monitored under climate and heavy traffic loadings. A composite pavement consisting of HMA over jointed plain concrete also was constructed in the field, by the Illinois Tollway north of Chicago. At the Tollway, extensive field surveys were performed on 64 sections of the two types of composite pavements.
This project also evaluated, improved, and further validated applicable structural, climatic, material, and performance prediction models, and design algorithms that are included in the AASHTO MEPDG and DARWin-ME, CalME, NCHRP 1-41 reflection cracking, NCHRP 9-30A rutting, and the Lattice bonding model. The current DARWin-ME overlay design procedure for HMA/PCC and a special R21 version of the Mechanistic-Empirical Pavement Design Guide (MEPDG [v. 1.3000:R21]) can be used for new PCC/PCC composite pavements.
To facilitate implementation, the project developed practical recommendations for construction specifications and techniques, life-cycle costing, and training materials.
In May 2008, a survey of in-service composite pavement sites in the Netherlands, Germany, and Austria was conducted to assess the design, construction, and performance of composite pavement systems. The results of this survey were published as First Fruits Report S2-R21-RW-1(2008 Survey of European Composite Pavements).
