Producing Eco-Friendly Concrete Paving Block Using Waste Refractory Brick Aggregates

Recycled aggregates derived from construction and demolition (C&D) waste are becoming popular alternatives for aggregates used to make sustainable construction materials. However, not all recycled aggregates from C&D waste can be used for structural concrete applications, owing to their characteristics. This study proposes the use of refractory brick waste (RBW) as a natural sand replacement for the production of eco-friendly concrete paving blocks (CPB) for non-traffic applications. RBW was used to replace natural sand by 15, 30, 50, and 100% by weight, and their engineering properties (density, compressive strength, water absorption, pulse velocity, and abrasion resistance), microstructures, and cost-effectiveness were compared with those of the reference CPB without RBW. The test results revealed that the CPB properties improved with the inclusion of RBW in the formulation. The optimum performance was obtained at 100% RBW because of the denser and more compact microstructure resulting from the pozzolanic reaction provided by the fine RBW particles than that in the reference CPB. Additionally, cost-effectiveness analysis demonstrated that material and production costs could be reduced by approximately 19.75 $/m3 and 10.41 $/m3, respectively, when 100% RBW is used as a natural sand replacement in the production of CPBs for non-traffic load applications. Thus, replacing natural sand with 100% RBW in CPB production fulfills the best technical and economic criteria for sustainable construction materials and can help in the preservation of natural resources.