Effect of micro-structure and mineralogical composition on the water demand and super plasticizer content of ternary blended self-consolidating paste.

Abstract

The characteristics of cement paste, mortar and the resultant concrete greatly depends on the mineralogical composition as well as the micro-structure of the cement and/or the supplementary cementitious materials. In this study, the effect of the mineralogical composition and microstructure of pulverised burnt clay (PBC) and palm oil fuel ash (POFA) on the water demand and high range water reducing admixture requirement of paste formulated from a ternary blend selfconsolidating high performance concrete was investigated. To characterise the supplementary cementitious materials, various tests were carried out. These tests include particle size analysis (PSA), X-ray diffraction (XRD), Scanning electron microscope (SEM), surface area analysis and chemical analysis (XRF). The results of the investigation revealed that POFA, OPC and PBC have a BET surface area of 23.7514 m²/g, 5.0670 m²/g and 2.9791 m²/g respectively. Although PBC has the least BET surface area, XRD results shows that it has the highest amount of quartz and glassy substances which present it as a flow enhancing material. Furthermore, paste formulated from a binary blend of OPC and PBC shows lesser flow time, lower HRWR dosage as well as water demand in comparism with paste formulated from a binary blend of OPC and POFA and also paste formulated from a ternary blend of OPC, POFA and PBC.