Mechanical Properties and Microstructure of Cementitious System with Portland Cement and Silica Fume at Low Temperature

At various temperatures,influence of different mixing amount of silica fume on mechanical properties and microstructure of composite cementitious system is studied.On condition of low temperature,different mixing amount(0,2%,5%,8%,10%) of silica fume is added into Portland cement after w hich the compressive and flexure strength of the cementitious mortar is tested and the scanning electron microscope(SEM) analysis is done.With the increase of mixing amount of silica fume,mechanical properties of the composite cementitious system are improved at the beginning and then tend to depress,w hile its structure gets dense all the time.When the mixing amount of silica fume reaches 8%,14d compressive and flexure strength of the composite cementitious system reach a maximum.As a result,low temperature can influence the development of mechanical properties of composite cementitious system,but adding silica fume can promote hydration of the composite cementitious system and strengthen microstructure of set cement.