Assessment of the Recycled Concrete Aggregates Structural Suitability for Road Construction

In most aspects of modem life, there is a consensus among practitioners and decision makers of the importance of preserving the environment, and to find alternatives to the scarce natural materials. This can be accomplished by better utilization of the natural materials and/or recycling or reclaiming their waste, specially, if they are of finite resources. The recycled material could be an attractive alternative (both environmentally and economically) if its characteristics are proven to be close to those of the natural material. Utilizing recycled mineral aggregates in the construction field in general and in highway pavement in specific is somehow governed by its ability to meet its intended function as carrying component within the structure. In the area of pavement construction, the suitability of the recycled aggregates is primarily judged by its ability to carry the high traffic loads effectively. The primary objective of this thesis is to study the suitability of using the Recycled Concrete Aggregates (RCA) for pavement construction or rehabilitation. The RCA is intended to replace the virgin material in one of the pavement layers, namely the subabse. The general characteristics of the RCA material (such as the grade distribution) are compared against the subbase material specifications. A testing model is built to quantify the RCA-layered pavement performance under various load levels, and to comparatively assess its behavior against the virgin mineral aggregates. The model dimensions are set large enough to replicate the pavement structures in reality to ensure accurate analysis. Several experimental settings are considered to account for the possible variability in the pavement loads (generated by the various vehicle types), material gradation, composition and thickness. The performance of the RCA material is captured through the resulting load-deflection relationships of the various settings. The results of these experiments indicated the good potential of the RCA as a subbase material. The resulting load-deflection relationships of both the RCA- and virgin-materials indicated the superiority of the RCA-material as a subbase material. In general the deflection results of the experiments indicated that the pavement deflection under load is generally lesser with the RCA material