Compressive strength and ultrasonic pulse velocity of concrete with metakaolin

Abstract

The intention of the present study is to assess the possibility of using Metakaolin as a partial replacement of Portland Pozzolana Cement (PPC) in the concrete to improve its workability and compressive strength. It also explores the study on the connection between ultrasonic pulse velocity (UPV) on different replacement percentage of mineral metakaolin and compressive strength by using a compression testing machine for M40 grade of concrete. Concrete specimens were cast of size 150 mmx150 mm x150mm by partial replacing PPC with metakaolin in the range of 4% to 28 % by the weight of cement. For better consistency and workability the Visco-Flux superplasticizer was used. Usual procedure of water curing of specimens was done for 7, 28, and 90 days to determine the effect of curing time on strength. All 8 different mix specimens were tested for compressive strength and ultrasonic pulse velocity. It was observed that up to 24% metakaolin replacement the strength was increased but after that, the strength gets reduced as compared to the normal concrete and the optimum value of compressive strength was obtained at 16% metakaolin replacement. The increase in the UPV of test samples indicated the formation of the homogeneous structure due to the addition of metakaolin. So the use of metakaolin as a partial replacement of PPC in concrete is a good choice to reduce the cost of production and increase the strength of concrete. A mathematical model is generated by regression analysis in the form of an equation to correlate the compressive strength and ultrasonic pulse velocity.