Influence of Metakaolin Content on the Properties of Pavement Quality Concrete

Abstract

The use of ordinary portland cement in infrastructure construction needs to be regularized due to sustainability issues. In this regard, there has been an emergence of supplementary cementing materials possessing pozzolanic characteristics. The objective of this paper is to partially replace the cement with metakaolin and investigate the effects of metakaolin on properties of Pavement Quality Concrete. Concrete mixtures with varying MK content of 0%, 5%, 10%, 15%, 20%, and 25% were prepared and various parameters were evaluated. The results showed that fresh concrete properties like plastic density and workability decreased when the MK content in the concrete was increased. As far the mechanical properties viz. compressive strength, flexural strength, splitting tensile strength and elastic modulus are concerned, an improvement was observed with the introduction of MK up to a MK content of 10%, but it reduced when MK content was further increased. The durability parameters such as water permeability and water absorption exhibited a decreasing trend which suggests that MK concrete exhibits high resistance compared to cement concrete. Regarding the ultrasonic pulse velocity (UPV) test, all the tested concrete specimens are ‘good’ quality concrete. The pulse velocity increased up to a MK content of 10% but, similar to strength parameters, UPV too reduced beyond the MK content of 10%. Hence, the study recommends an optimum replacement amount of 10% of cement content by MK. The study confirmed the positive effects of the utilization of metakaolin for partial replacement of cement in PQC as a supplementary cementing material.

Keywords: OPC, Metakaolin, PQC, Workability, Mechanical properties, Durability, UPV