Effect of Hydroxide Sludge Waste on Mechanical Properties of Masonry Bricks

The aim of this work focuses on the behavior of the masonry bricks incorporating hydroxide sludge wastes (in the calcined state (600 ℃) named CHS). Chromium and copper were the predominant metal oxides in the waste. Brick samples were formed with mixtures of different proportions of CHS and clay (ie: x = 5, 10, 15, and 20 wt% of CHS and 100-X of clay) and fired at 950 ℃ for 1 h. Open porosity decreases from 39% to 32% with 0 to 20% of CHS, respectively. Moreover, the incorporation of the CHS into the clay mix clearly decreased the linear shrinkage and the water absorption. The compressive strength decreased by a maximum of 10 wt% of CHS giving a value of 33 MPa. The evaluation of the release of the chemical species (Cr³⁺, Zn²⁺, and Cu²⁺) by a leaching test indicates successful stabilization of the pollutants in the bricks.