Mechanical Properties and Frost Resistance and Durability of Fully Mixed Recycled Aggregate Concrete Modified with Nano-SiO2 and Fiber Composite for Soil Solidification Rock

To sum up, using SSR instead of cement as a cementitious material to make concrete has positive social and economic benefits and significant ecological and environmental benefits, which is in line with the global industrial policy of energy saving and emission reduction and the development of the circular economy. The introduction of NS, PPF, and recycled carbon fiber (RCF) effectively improves the inherent defects of RAC. However, the mechanism of SSR, RCF, and PPF composite concrete is complex, and the influence of SSR on the mechanical properties and frost resistance of concrete needs to be further explored. This study provides practical technical support for the engineering application of SSR RCAC. As shown in Fig. 1, the compressive and flexural strength tests were conducted after 7 days, 28 days, and 60 days of curing cycles by adjusting the amount of SSR (9%, 12%, 15%) and adding different proportions of NS, PPF (0.1%, 0.3%, 0.5%) and RCF (0.25%, 0.5%, 0.75%). To evaluate the mechanical properties of concrete. In the freeze-thaw (F-T) cycle test, the frost resistance of concrete was comprehensively studied by analyzing the mass loss rate (MLR), relative dynamic elastic modulus (RDEM), and residual compressive strength of concrete. At the same time, the microstructure of concrete was deeply analyzed by SEM, and the mechanism of composite reinforcement of RCF, PPF, and NS in SSR RCAC was revealed.