Comparative study on properties of recycled aggregate concrete using recycled aggregates coated with different pozzolanic materials

Abstract

Abstract Recycled aggregates (RA) are the aggregates obtained from reprocessing materials, which were earlier used in constructions. The use of RA contributes to reducing waste and energy consumption and achieving sustainability. Several investigators have attempted to develop concretes using RA; however, the concrete so produced exhibited poor performance concerning workability and strength properties. The poor performance is found to be mainly due to high porosity and water absorption properties occurred due to the presence of sticked mortar to the RA surface. This fact necessitated proper treatment of RA so that the recycled aggregate concrete (RAC) could enhance its performance. In this paper, M20 grade RAC has been developed using ‘RA’ without and with coating of different pozzolanic materials viz., fly ash (FA), ground granulated blast furnace slag (GGBS), microsilica (MS), ultrafine slag (US) and other ingredients viz., cement, crushed sand, water and chemical admixture. Results of the experimentation show that the average workability (slump) and strengths of RAC produced using ‘RA’ coated with different pozzolanic materials increased by 102% and 17.27% respectively when compared to the RAC produced using RA without coatings. The RAC with RA coated using GGBS has shown higher strength (31.80 MPa) amongst the others. Further, the workability and strengths of normal concrete are found to be more by 108% and 19.38% respectively when compared to normal concrete. The study concludes that, RA coated with Pozzolanic materials can be considered as an alternative to NA for producing the concretes as they satisfy the required workability and strength properties.