Improvement of mechanical properties of high-volume recycled powder concrete by a novel compression casting method

Use of recycled powders (RPs) as partial substitutes for Ordinary Portland Cement (OPC) in concrete promotes eco-friendly construction and better resource utilization. However, high-volume RP concrete typically exhibits lower performance due to the limited reactivity of RPs. This study addresses this concern by employing a novel compression casting method to enhance the mechanical and durability properties of RP concrete. The effects of the casting method, RP types, RP proportions and water/binder ratio on the properties of RP concrete were systematically investigated. The results showed that compression casting significantly enhanced the mechanical properties, durability, and microstructure of RP concrete. Compared to normal-cast RP concrete, the maximum increases in compressive strength and elastic modulus of compression-cast specimens were 203 % and 100 %, respectively. Notably, compression-cast concrete incorporating 45 % RPs achieved comparable or superior properties to conventional concrete containing 100 % OPC. Additionally, empirical models for predicting compressive strength, elastic modulus, and stress-strain relationships for compression-cast and normal-cast RP concrete were developed and validated. The use of high-volume RPs in compression-cast concrete demonstrates significant environmental and economic benefits, highlighting this approach as a promising solution for producing sustainable, high-performance RP concrete.