"Composite pavements have proved in Europe and the United States to have long service life with excellent surface characteristics, structural capacity, and rapid renewal when needed. Based on statistics compiled in 2000, approximately 30% of the urban interstate system and just over 20% of the rural interstate system is classified as "composite" pavement. In most cases the composite pavements are the result of maintenance and rehabilitation activities and not intentionally designed new composite pavement systems. This project developed the guidance needed to design and construct new composite pavement systems. The research determined the behavior, properties, and performance for both HMA/PCC and the PCC/PCC composite pavements under many climate and traffic conditions. Experimental composite pavements were constructed at MnROAD in Minnesota and the 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. The key to the sustainable features of new composite pavements is the ability to use higher levels of recycled materials in the lower concrete layer. Additionally, the thickness of the lower concrete layer can be reduced when considering the insulating effect of the top pavement surface. Intentionally designed and constructed composite pavements will help highway agencies meet the goal of building economical, sustainable pavement structures that use higher levels of recycled materials and locally available materials"--Foreword.