Comparative study on the effects of nano-SiO_2, nano-Fe_2O_3 and nano-NiO on hydration and microscopic properties of white cement

摘要

This paper presents the effects of nano-SiO2 (NS), nano-Fe2O3 (NF) and nano-NiO (NN) on hydration and microscopic properties of white cement. Cement was partially replaced by NS of 15 nm and 50 nm, NN of 15 nm, and NF of 50 nm, respectively. Results show that nanoparticles can promote cement hydration and shorten the induction period. The initial setting time and final setting time of cement paste are shortened by introducing different nanoparticles, and NS with the average diameter of 15 nm has the best performance in terms of shortening the setting time. Besides, compressive strength of mortars containing nanoparticles are higher than that of pure cement mortar. Furthermore, the mass loss of the mortar containing NS of 15 nm is the slowest during drying process. Compared with pure cement paste, the calcium hydroxide content is reduced in the systems containing NS due to pozzolanic activity and increases in the NN and NF systems due to nucleation promoting hydration. The lowest porosity of NN system is mainly attributed to nucleation and filling effect. (C) 2019 Published by Elsevier Ltd.