The exploitation of sludge from aggregate plants in the manufacture of porous fired clay bricks

Aggregates (gravel and sand) are, after water, the Earth's second most used natural resource, representing about 50% of all consumed mineral resources. Aggregate production generates a large quantity of waste from the aggregate washing process. This waste is made up of suspended solids - sludge - which has a great environmental impact. It is deposited in huge troughs because of the impossibility of discharging it directly into rivers. Many plants have incorporated decanters and filter presses to separate the solid from the liquid fraction. This paper evaluates the possibility of exploiting the solid fraction (i.e. sludge) in the manufacture of fired clay bricks. The added value of these bricks is, on the one hand, the exploitation of sludge as a currently useless waste product, and on the other, the use of this sludge to enhance the physical and mechanical properties of conventional fired clay brick