Study on the compressive mechanical properties of mixed recycled aggregate concrete with silane modified

Abstract

This study used a 10% silane solution to strengthen recycled brick aggregates (RBA). Subsequently, mixed recycled aggregate concrete (MRAC) was prepared by using recycled concrete aggregate (RCA) and RBA modified with silane (Si-RBA). The properties of RBA and RCA were compared. The effects of the Si-RBA/RCA ratio on the failure modes, compressive strengths, and characteristics of the compressive stress strain curves under monotonic loading and cyclic loading were tested. The microstructures of the RBA, Si-RBA, and MRAC were analyzed by scanning electron microscopy (SEM). The test results showed that RBA modified with silane reduced water absorption by 51.61% and improved the crushing index by 14% compared to RBA. When the Si-RBA/RCA ratio changed from 0:10 to 10:0, the failure mode of MRAC transformed from interfacial transition zone (ITZ) failure to aggregated failure, while the compressive strength decreased. The MRAC specimens exhibited similar failure phenomena, regardless of monotonic or cyclic loading. The peak stress and elastic modulus decreased as the Si-RBA/RCA ratio increased, whereas the peak strain showed a fluctuating growth trend, and the plastic strain increased. In addition, SEM images showed that the reaction products of silane filled the pores of the RBA, and the silane solution made the ITZs of the RBA much denser. Based on the test data, a constitutive model for MRAC under monotonic and cyclic loadings was proposed, which showed good accuracy in predicting the response of MRAC under a compressive load.