Utilization of coal bottom ash in recycled concrete aggregates based self compacting concrete blended with metakaolin

Abstract

Conservation of natural products and recycling in concrete industry wastes are the foremost needs of the current period. Intense utilization of alternate materials in concrete manufacturing has already been initiated from the past few decades. The present investigation has been piloted to evaluate the overall feasibility of Self Compacting Concrete (SCC) prepared with Coal Bottom Ash (CBA) and Recycled Coarse Concrete Aggregates (RCA) by replacing of Normal Fine Aggregates (NFA) and Normal Coarse Aggregates (NCA) respectively. The performance of SCC prepared with coal industry by-products [Fly Ash (FA), CBA] and construction industry wastes (RCA) has been evaluated experimentally. Various mechanical (compressive and tensile) and long-term (chloride permeability, capillary suction, accelerated carbonation, electrical resistivity, ultrasonic pulse velocity) properties of SCC prepared with different proportions of RCA and CBA have been estimated. The investigation inferences that the incorporation of constant amount of CBA (10%) along with varying content of RCA (up to 50%) has been proved to be advisable for the use in construction industry as enhanced/equivalent performance compared to that of control SCC has been achieved. Ample variation in the results of experiments conducted on SCC mixes has been noticed with increase in content of RCA. To capture the observed loss in the behavior of SCC prepared with higher alternate levels (>50% RCA) and CBA, Metakaolin (MK) has been inculcated. The attained findings revealed that the inclusion of MK (along with other by-products) results in comparable/at-par performance for SCC prepared up to full alternate levels (100%) of NCA with RCA.