Influence of Mineral and Chemical admixtures in Ordinary Portland Cement on Physical and Mechanical Properties

Abstract

The supplementary cementious materials (SCMs) or mineral admixtures like fly ash, silica fume, metakaolin and ground granulated blast furnace slag (GGBS) are used in cement composite by partial replacement of cement about 20%. The effect of SCMs in Ordinary Portland cement (OPC) with regard to water requirement for consistency, setting time and cement mortar cubes with and without addition of super-plasticizer (SP) has been studied. It has been observed from the experimental studies that the cement consistency for OPC is 27.5% and addition of different mineral admixtures demands more water than cement consistency. Particularly, the mix with metakaolin demands 39% water for consistency. It is observed that with the addition of SP, the water required for consistency found reduced to 25% in all the mixes. The use of mineral admixtures influence fast setting time and with the addition of SP, the setting time is much faster. For preparation of mortar cubes demand 1 % more water as compared to IS-1489. XRD test has been conducted on cement and other cementitious materials, such as fly ash, silica fume, metakaolin, GGBS, to know the nature of particles present in that, which have more influence in imparting strength property. River sand and standard sand has been used in the present study. The compressive strength has been determined for these mixes at 3, 7, 28, 56 and 90days and the compressive strength determined at 90 days indicates that all the mixes with mineral admixtures give more or less same strength except the mix with fly ash in both conditions i.e. with river and standard sand, which gives 10.20 % less by using River sand and 16.5% less by using standard sand. With the addition of SP, the compressive strength of cubes prepared using river and standard sand is more compared to the strength of cubes prepared without SP. The compressive strength of the mortar cubes using standard sand gave better results on compared to cubes using river sand. The compressive strength of cubes for silica fume using River sand gave higher strength of about 56.38Mpa and by using standard sand cement with silica fume gave higher strength of about 57.52MPa. With the addition of SP, the compressive strength of the mortar cubes using river and standard sand, silica fume gave higher strength of about 60.25 and 61.11MPa respectively.