EFFECTS OF PHOSPHORUS SLAG ON HYDRATION PROPERTIES AND PORE STRUCTURE OF CEMENT PASTE

Effects of phosphorus slag on the hydration properties and pore structure of cement paste were studied by determining the setting time, the hydration heat and the compressive strength of cement pastes, and using scanning electron microscopy and differen- tial thermal-thermo gravimetric analysis. The results show that an increase of phosphorus slag replacement causes a longer setting time of cement pastes, a decrease of hydration heat and compressive strength at 7 d. However, the compressive strength of hardened pastes at 90 d is close to or surpasses that of pure cement paste, the influence of phosphorus slag replacement on the compressive strength at later age is not significant. The calcium hydroxide contents in the pastes decrease with the increase of the phosphorus slag replacement, but increase with the extension of the hydration days. The pozzolanic activity and filling function of phosphorus slag efficiently improve the microstructure and pore structure of cement pastes at later hydration age.