Research on the performance and strengthening mechanism of composite-enhanced recycled aggregate concrete

Abstract

The application of recycled aggregate concrete (RAC) greatly promotes the sustainable development of engineering construction, and improving its performance can further expand its practical application range. In order to obtain higher performance RAC, this article selects two composite pre-treatment methods: cement silica mortar wrapping organosilicon immersion, water glass soaking, and organic silicon soaking to enhance the performance of recycled aggregate (RA). Subsequently, the composite reinforced RAC was poured, and their mechanical and durability properties were tested. The strengthening mechanism of the composite pre-treatment method was analyzed. The results show that compared with the single-treatment method, the composite strengthening method has an effect of increasing the apparent density of RA by 0.2%∼4%, and the effects of reducing the crushing value and water absorption are increased by 0.5%∼7.2% and 0.4%∼4.7%, respectively; both composite strengthening methods can improve the mechanical and durability properties of RAC. Analysis of the samples using SEM, TG, and XRD showed that both composite strengthening methods filled the microcracks and pores on the surface of the old mortar layer of RA and promoted the hydration of cement in the transition zone between the RAC interfaces, thereby increasing the interface strength and improving the mechanical and durability properties of RAC.