Characteristics of Concrete Prepared with Metakaolin and Recycled Coarse Aggregates

Abstract

The study tries to demonstrate the effect of metakaolin to enhance the qualities of concrete prepared with natural coarse aggregates (NCAs) and recycled coarse aggregates (RCAs). Recycled aggregate concrete (RAC) mixes are made by substituting NCA with 100% RCA and ordinary Portland cement with 10, 15 and 20% metakaolin. The workability of fresh concrete mixes is evaluated by slump test. Mechanical properties of concrete are evaluated by means of compressive strength, splitting tensile strength and flexural strength after 28-day curing, and the corresponding results are collated with reference concrete. The outcomes of the study indicate that the compressive strength as well as splitting tensile and flexural strength decrease when natural aggregates are replaced with 100% RCA. However, the use of metakaolin up to 15% enhances the properties of both natural and recycled aggregate concrete. The recycled aggregate concrete mixes show optimum performance at 15% metakaolin replacement level and hence can be used in practical fields.