EFFECT OF ADDING MICRO AND NANO SILICA ON THE PROPERTIES OF CEMENT MORTAR

Abstract

Nano Silica is a very soft and highly reactive substance, it is a pozzolanic material and can be used as an additive to Ordinary Portland Cement for the manufacture of cement mortar in order to improve some properties. Nano Silica and Micro Silica were imported for this investigation. Nano Silica was added to cement in several ways including; the method of normal mixing, mixing with water, and mixing with grinding. Tests were carried out to assess these different methods and the results showed that the best method is mixing with grinding. In this study, Nano Silica was added in substitution of 1, 3 and 5%, and Micro Silica in substitution of 3, 6 and 10% of the weight of ordinary Portland cement. The experimental program of this study included the mixing and pouring the samples of cement mortar to test the initial and final setting times and pressure resistance after 7, 28 and 90 days of curing. All samples were cured by immersion in water, where the results showed that the addition of Nano Silica improves the properties of cement mortar and has a positive effect on the early compressive strength compared to the Ordinary Portland Cement. It was noted that the best addition ratio was 3% which achieved a higher strength than the reference sample with an increase of 52%. Moreover, the addition of Nano Silica influenced the initial and final setting times, and this clearly occurs with the increase in the percentage of the addition where the setting times decreased. This effect can be attributed to the role of Nano Silica in accelerating the initial and final times which lead to get early resistance.