An Investigation of the use of Ternary Blended Cement in the production of High Strength Concrete

Abstract

This study focused on the possibility of producing high strength concrete using ternary blended cement i.e. three part blended cement produced by partial replacement of OPC with a blend of metakaolin and limestone in a ratio of 2 : 1. The compressive strength of three replacement mixes i.e. with 15%, 30% and 45% replacement of OPC with a metakaolin-limestone blend was compared to that of a control mix (100% OPC) at 3, 7, 28, 56 and 91 days using the Strength Activity Index (SAI) method. The 15% replacement mix had the highest strength at all ages. The 30% and 45% replacement mixes achieved 90% and 60% (respectively) of the control mix strength by 91 days. The replacement mixes especially the 15% replacement mix exhibited high early age strength as compared to the control mix predominantly due to the filler effect of the limestone and metakaolin fine particles. The replacement mixes also exhibited strength gains at later ages predominantly due to the extended pozzolanic reaction of the metakaolin particles. Basing on the SAI values, we concluded that this ternary blend has potential for applicability in production of high strength concrete at OPC replacement levels between 15 and 30%. This study also highlighted the need for further research into optimum blend ratios between metakaolin and limestone and the optimum replacement percentage of OPC with a metakaolin-limestone blend in concrete mixes