Improvement of stress-strain behavior of brick-waste aggregate concrete using low-cost FCSM composites

Reusing the waste materials generated from demolishing existing infrastructures can play a vital role in minimizing their detrimental environmental impacts. A substantial portion of the total construction waste comprises brick wastes (B-waste). It has already been established that recycled aggregate concrete (RAC) fabricated using recycled clay brick aggregates (CBA) lacks adequate compressive strength and corresponding strain. This limits the application of RAC-CBA to mainly non-load-bearing works. External strengthening of RAC using fiber reinforced polymer (FRP) sheets has been found beneficial in terms of the improvement in ultimate compressive strength and ultimate strain. With massive costs associated with synthetic FRP sheets, this study proposes the use of Fiberglass Chopped Strand Mat (FCSM) sheets as a low-cost alternative to synthetic FRP sheets to improve compressive strength and behavior of RAC-CBA. To accomplish this, RAC was constructed with three different waste brick aggregates, mainly hollow-clay, solid-clay, and hydraulic cement-clay interlocking bricks. Typical cylinders of size 150 mm in diameter × 300 mm in height were cast and strengthened using 2, 4, and 6 layers of FCSM sheets. It was found that FCSM sheets successfully enhanced the ultimate compressive strength and strain of RAC-CBA irrespective of the type of constituting brick aggregates. Further, a correlation in the improvement of axial compressive behavior was found with the number of external FCSM sheets. The accuracy of existing ultimate strength-strain models was assessed in predicting the experimental ultimate stress and strain. In general, none of the existing models exhibited a consistent trend in predicting the axial behavior of RAC-CBA. Hence, the ultimate stress–strain models were proposed.