Study on the Modification of Sulphoaluminate-ordinary Portland Cement-based Materials by Silica Fume Content

The water demand of the composite cement increased and the setting time was prolonged by adding silica fume to the sulphoaluminate cement with large amount of ordinary Portland cement.When the silica fume content was 6%,the dry shrinkage rate of the composite cement mortar reached the minimum value of 0.0403% at 60 days.The appropriate amount of silica fume can improve the strength and carbonation resistance of cement mortar in the middle and late stages,and the addition of 4% silica fume has the best effect on the freeze-thaw resistance of mortar.The hydration mechanism of composite cement system with silica fume was analyzed by means of micro-test from the degree of cement hydration and the micro-morphology of hydration products.