Development of Improved Guidelines and Designs for Thin Whitetopping: Literature Review

Thin whitetopping, also known as thin bonded concrete overlay on asphalt (BCOA), is a rehabilitation alternative consisting of a 0.33 to 0.58 ft (100 to 175 mm) thick portland cement concrete (PCC) overlay of an existing flexible or composite pavement. It has been frequently used in different U.S. states and in other countries in the Americas, Europe, and Asia. This technical memorandum constitutes the literature review for Partnered Pavement Research Center Strategic Plan Element (PPRC SPE) Project 4.58B, whose primary goal is to develop recommendations and guidance on the use of thin BCOA as a rehabilitation alternative in California. Different state-of-practice documents as well as specific technical papers and reports have been analyzed. This analysis shows that even though thin BCOA is a mature technology, further development and improvement will help to optimize its design as a rehabilitation alternative for California. The analysis shows that some critical elements do not seem to have been adequately explored to date. Performance of the interface between PCC and asphalt is one of these elements. Other critical elements are the characterization of the asphalt base, the interaction between asphalt and PCC distresses, and the mechanics of thin BCOA faulting. The application of internalcuring concrete technology, the use of fibers, and the optimization of Caltrans PCC mixtures for thin BCOA rehabilitation projects are also considered to warrant further research. Furthermore, little experience exists concerning the use of new asphalt mixtures before BCOA overlays, and no reference was found where rubberized mixtures had been used. Thin BCOA has been used as an alternative for the rehabilitation of asphalt pavements that were not highly deteriorated, which has limited the number of rehabilitation projects where the technique could be applied.