The effect of recycled concrete powder (RCP) from precast concrete plant on fresh and mechanical properties of cementitious pastes

This study aims to evaluate the effect of RCP from a precast concrete plant on rheological and mechanical properties of cementitious pastes. In the study, Portland cement was replaced by RCP in 10, 20, and 30% (in mass). The hydration kinects of cement with RCP was studied through isothermal calorimetry. The fresh properties were assessed using mini-slump test and rotational rheometry. The mechanical properties were evaluated through compression tests and the microstruture was studied using Scanning Electron Microscopy. RCP reduces fluidity of the pastes, by increasing both yield stress and plastic viscosity. The addition of RCP accelerates the hydration of cement, while reducing the released heat. RCP also reduces the compressive strength and elastic modulus of the pastes. The use of RCP as partial substitute for cement is viable, due to its size distribution and specific surface area.