Development of sustainable light weight concrete tiles incorporating fine recycled brick and concrete aggregates

Unconventional lightweight concrete (LWC) can utilise waste ingredients to replace natural aggregates, providing a viable approach for waste management, decreasing LWC production costs, and reducing dependence on natural aggregates. The present study aimed to develop sustainable LWC tiles differing in waste aggregate amounts and types. The waste aggregates used originated from recycled clay bricks and recycled concrete. Six different types of concrete mixes were prepared in this experimental investigation. These are; two reference mixes (NWC and LWC without aggregate replacement), two LWC mixes with 50% and 100% fine recycled brick aggregate (RBA), and another two LWC mixes with 50% and 100% fine recycled concrete aggregate (RCA). The intended compressive strength for the reference LWC mix was 35 MPa, with a water-to-cement ratio of 0.35. The produced LWC mixes were evaluated in terms of compressive strength, splitting tensile strength, fracture load, modulus of rupture, density, and water absorption. The findings indicated that reasonable mechanical properties can be achieved when replacing natural fine aggregates with fine RBA or RCA in LWC, with densities between 1722 and 1613 kg/m3, regardless of the replacement ratio. Moreover, the test results showed that despite increases in water absorption and decreases in fracture load of tile specimens for both RBA and RCA-based LWC, all the produced tiles, except for LWC with 100% RBA, met the requirements of the Iraqi standard and can successfully be used as a sustainable structural LWC.