The hydration, pore structure and strength of cement-based material prepared with waste soaking solution from acetic acid treatment of regenerated aggregates

Abstract A zero-waste process to treat recycled concrete aggregates (RCAs) was carried out through immersing them in acetic acid solutions with concentrations of 0.1, 0.2 and 0.3 mol/L. The waste soaking solutions collected after the immersion process were used as mixing water for preparation of cement paste and mortar samples. After mixing and curing, setting time, fluidity, heat evolution, strength and pore structure over time were tested. Results showed that the waste soaking solution can slightly prolong the setting time and increase the initial fluidity and fluidity loss of the produced cement paste. It is found that both the flexural and the compressive strengths of the mortars at 28 d increased with the immersion treatment duration, and were higher than that of the reference group. The decrease of the porosity and the refinement of the pores in the cement paste with the waste soaking solution account for this increase of the strength with immersion treatment duration. However, the strength of the mortars decreased when the acid concentration increased from 0.2 mol/L to 0.3 mol/L. This is because more pores larger than 100 nm were produced in the pastes by the acid with higher concentration.