Characterization of metakaolin and study on early age mechanical strength of hybrid cementitious composites

In this study, the potency of using laboratory produced metakaolin as partial replacement of cement in the evolution of a hybrid cementitious composites (HCC) was investigated. Some chemical composition and phases of metakaolin were appraised with the aid of X-ray fluorescence (XRF) and X-ray diffraction. Particle size analyzer was used to study the physical properties of metakaolin produced in the laboratory from purified Kaolin. Early age mechanical strength and shrinkage properties of structural grade HCC developed by replacing fly ash in the original ECC M45 design with metakaolin (MK), colloidal nanosilica (CNS) and epoxy were examined. The designed mixtures consist of five mixtures with the control and base mix exposed to water and seawater. The control mix consists of only the fine aggregate and cement while the base mix consists of cement, fine aggregate, 10% MK and CNS with epoxy resin at 1% each by weight of the binder. Synthetic barchip fibres and some natural fibres namely, oil palm fruit bunch and coconut fibres were incorporated. The water cement ratio was designed as 0.30 for all mix ratios. The result reveals that the inclusion of MK, CNS and epoxy have a significant effect on the fresh properties of the HCC and at early age of 7, 28 and 90 days. The mechanical strengths were better improved than the standardized M45 ECC at these early ages.