Feasibility of concrete mixtures containing coarse and/or fine recycled brick aggregates

This paper assesses the feasibility of concrete mixtures containing high replacement rates of fine and/or coarse waste brick aggregates. Three mixture series prepared with different water-to-cement ratios are tested for workability, compressive strength, split tensile strength, modulus of elasticity, water permeability (by capillary or under pressure), and drying shrinkage. Test results showed that the concrete properties remarkably degrade when the coarse natural aggregate fraction (i. e., retained on sieve No. 4) is fully replaced by recycled waste bricks, given their increased porosity that reduces the concrete density and weakens its skeleton. In contrast, the strength and durability remained almost unaltered when the fine natural aggregate fraction was replaced by 50 % recycled waste bricks, and considerably better than equivalent mixtures made using the same amount of recycled fine aggregates derived from hardened waste concrete.