Paper Title
Characteristics of Cement Mortar with Nano-SiO2 Particles

Abstract
The properties of cement mortars with nano-SiO2 were experimentally studied. The amorphous or glassy silica, which is the major com- ponent of a pozzolan, reacts with calcium hydroxide formed from calcium silicate hydration. The rate of the pozzolanic reaction is pro- portional to the amount of surface area available for reaction. Therefore, it is plausible to add nano-SiO2 particles in order to make high-performance concrete. The experimental results show that the compressive strengths of mortars with nano-SiO2 particles were all higher than those of mortars containing silica fume at 7 and 28 days. It is demonstrated that the nano-particles are more valuable in enhanc- ing strength than silica fume. In addition, the continuous hydration progress was monitored by scanning electron micrograph (SEM) obser- vation, by examining the residual quantity of Ca(OH)2 and the rate of heat evolution. The results of these examinations indicate that nano- scale SiO2 behaves not only as a filler to improve microstructure, but also as an activator to promote pozzolanic reaction. © 2006 Elsevier Ltd. All rights reserved. Keywords: Nano-SiO2; Silica fume; Compressive strength; Micro-structure; Filler; Activator