Recycling of construction wastes for manufacturing sustainable bricks

The purpose of this study was to manufacture sustainable bricks, based on three types of wastes generated in the building industry: wood-cutting residues, wastes from the excavation process and recycled aggregates (RA). Water was added as the kneading material, and Opuntia ficus-indica extract (mucilage) was supplemented as a natural additive to improve the workability of the mixtures. The conventional firing process was substituted by drying in a solar drying chamber. Nine mixtures were prepared using 62% excavation wastes, 5% wood-cutting residues and 33% RA. These mixtures were classified into two groups depending on their granulometries: the first one denominated cementitious RA only having granulometries from 3/8 inch (0·95 cm) and 1/4 inch (0·63 cm) to fines and the second group denominated all-in-one RA having granulometries from 1/4 inch to fines. The quality of the sustainable bricks was evaluated according to compressive strength and water absorption parameters. The results showed that the ecological bricks manufactured with the mixture of cementing RA only of 3/8 and 1/4 inch to fines meet the standard requirements, providing compressive strength values of up to 8 MPa; moreover, the use of O. ficus-indica extract as a natural additive notably improved the workability of the mixture.