Rheological characteristics of self-compacting concrete mixtures containing metakaolin, ground granulated blast-furnace slag and fly ash

Abstract

Supplementary cementitious materials (SCMs) have been recently used in self-compacting concrete (SCC) in order to make it cost effective, better performance and also reduce the overall greenhouse gas emissions associated with the production of concrete. In this study, the rheological properties of 18 SCC mixtures with various SCMs were investigated for a constant slump flow value. In order to achieve this, Portland Cement (PC) as the main binder were replaced by various percentage of Metakaolin (MK), Ground Granulated Blast-furnace Slag (GGBS) and Fly Ash (FA) in two water/binder ratios. Results showed that MK increased high range water reducing admixture (HRWRA) demand and decreased rheological aspects due to the finer particles and also higher amount of aluminium. However the opposite tendency was observed when FA was incorporated with PC as the spherical fly ash particles makes it easier for the SCC mix to flow. Moreover, substitution of PC with GGBS increased HRWRA required in the SCC mixture having constant slump flow but no change on the other rheological properties. Scanning Electron Microscopy (SEM) and Energy dispersive X-ray spectroscopy (EDS) were used to understand the microstructural properties of SCMs.