The effects of polyaluminum chloride (Pac) on the mechanical properties of opc-fly ash cement

Abstract

An experimental study was carried out on the effects of polyaluminum chloride (PAC) on the mechanical properties of cement mixed with ordinary Portland cement (OPC) and fly ash (FA). PAC is a flocculant for water treatment and consists of aluminum and chloride ion. FA replaced 20, 40, and 60% of the OPC mass. PACs were mixed at 0, 2, 4, 6, 8, and 10% of the mixing-water mass. As a result, the compressive strength increased and the pore diameter and total porosity decreased as the amount of PAC increased. PAC also formed Friedel’s salt. In the microstructure analysis, Friedel’s salt formed in the pores was observed. OPC-FA cement paste using PAC forms a dense hydration reactant. However, as the FA substitution rate increases, the overall compressive strength decreases, so an additional method is needed to improve the initial strength. In conclusion, PAC affects the hydration of OPC-FA paste, which changes the pore structure, the hydration reactant and improves the compressive strength. ? 2020 by Korea Concrete Institute.