Laboratory Evaluation of Recycled Concrete Aggregate and Recycled Clay Masonry Blends in Pavement Applications

Abstract

Abstract This paper presents the assessment of blends of recycled clay masonry (RCM) with recycled concrete aggregate (RCA) for applications in pavements. The study reviewed materials from two South Australian suppliers with the proportion by dry mass of RCM being up to 30 % of the total aggregate mass. Testing included drying shrinkage, static undrained triaxial shear strength and multi-stage repeated loading triaxial testing (RLTT). Although the target dry density ratio was set at 98 % of maximum dry density (MDD) for all compacted specimens, moulding moisture content was varied to investigate the influence of moisture on strength and stiffness of the materials. Static shear strength decreased almost linearly as the initial moisture content increased. The importance of shear strength was demonstrated on RLTT testing and the applied stress states in later stages of the test. A review of the RLTT data showed that both resilient modulus and permanent strain were sensitive to molding moisture content, as well as the applied stresses. Recommendations based on the permanent strain behavior and resilient modulus of the tested specimens, were made regarding the general applications of the various blends in road construction. Potential applications ranged from upper or lower sub-base and base for various traffic levels, depending on percentage of crushed masonry, or RCM, initial moisture content, and product supplier.