Abstract
Hassan Darwish
The effect of silica nanoparticles (SNP) addtion on the specific characteristics of Portland cement pastes was investigated. The results revealed that the addition of SNP to the fresh Portland cement pastes reduced both w/c ratio and setting times, but increased significantly the early age strength development. The presence of the water-reducing admixture (Na-lignosulphonate) further improved the wokability and performance of cement pastes.The replacing of SNP up to 1.5 wt. % at the expense of cemen improved and enhanced the combined water content, bulk density, total porosity and compressive strength at all curing ages of hydration. The cement mix incorporated 1.5 wt. % (Sn3) is considered to be the optimum cement patch, where it exhibited the best results and were becoming better and higher than those of the pure cement (Sn0) at all curing stages of hydration. With the addition of more than 1.5 wt. % SNP to the cement (Sn4 and Sn5), all cement properties were adversely affected. Therefore, the higher additions of NSP must be avoided.
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