Investigation on alkali activated recycled cement mortar powder cementitious material

摘要

The effect of cement/sand ratio of the original mortar, type of the activators and addition of slag powder on alkali activated recycled cement mortar powder (AARCMP) pastes were studied. The results show that the cement hydrates in recycled cement mortar can be activated by alkali to reconstruct new cementitious substances. Water glass is more effective as an activator than NaOH. Recycled cement mortar with higher original cement/sand ratio yields higher strengths, and addition of slag powder can remarkably increase the strengths of the materials. AARCMP paste with the 28 day flexural and compressive strengths of 7.5 and 45.4 MPa respectively was prepared by replacing 30% slag powder for the recycled mortar powder. Scanning electron microscopy revealed that there is a great difference between the microstructures of the hardened paste of AARCMP and that of ordinary Portland cement.