Abstract: Hand stirring, mechanical stirring and ultrasonic were used to disperse nano-SiO2.The nano-SiO2 dispersion was studied by measuring nano-SiO2 colloidal particle size and particle size distribution using Zeta potential analyzer and its effects on the strength and capillary water absorption of cement mortar were analyzed as well.The research results show that the dispersion effect of ultrasonic dispersion is the best among the three dispersion methods, the mechanical stirring is the second and the manual stirring is the worst.With the increase of ultrasonic time, the average particle diameter of nano-SiO2 colloid decreases, and dispersibility of nano-SiO2 increases.The time of ultrasonic is more than 10 min, small particles of nano-SiO2 colloid increase, but the particle size distribution curve shifts to the larger particles, resulting in no obvious improvement in dispersibility.The strength of cement mortar and capillary water absorption relate with the dispersibility of nano-SiO2.With the increase of nano-SiO2 dispersibility, strength of cement mortar increases, capillary water absorption coefficient decreases,and density of mortar is improved.

Key words: nano-SiO2;dispersion way;strength;capillary water absorption