Modeling for Predicting Triaxial Mechanical Properties of Recycled Aggregate Concrete Considering the Recycled Aggregate Replacement

To theoretically investigate the triaxial mechanical behavior of recycled aggregate concrete (RAC), four series of samples, a C30 conventional concrete (CC) and three RACs with different recycled aggregate (RA) replacement ratios (20 %, 50 % and 80 %), were prepared. The triaxial compression tests with 0, 2, 4 and 8 MPa confining pressures were performed. Experimental results showed that the difference in failure stress decreased from 30.0 % to 2.7 % with increasing the confining pressure for the four series of concretes. This means that for failure stress, the influence of RA replacement ratios on the low confining pressure condition should be taken into account while its effect trends to decrease or even can be neglected with increasing the confining pressure. Furthermore, the elastic properties and the evolution of plastic characteristics were also related to the RA replacement ratio. Based on the test results, this study develops a modified elastoplastic model to accurately predict the triaxial mechanical behavior of RAC. The proposed non-integer high order failure criterion can better reflect the confining pressure sensitivity, while the associated flow rule can well describe the elastoplastic transition with increasing the confining pressure. Moreover, the influence of RA replacement was analyzed, and the parameters related to RA replacement ratios were considered in this model. Comparing the numerical simulations with the experimental results, it was concluded that the present modeling can well predict the main mechanical behavior of both CC and RACs by introducing RA dependent parameters.