Use of Natural Phosphate Wastes in the Manufacture of Construction Bricks

Purpose. Valorization of phosphate waste and diversification of the range of bricks by improving their mechanical properties. In this context, our work focused on the use of phosphate wastes from Djebel Onk (Tebessa) combined with clays from the Sidi Aich region (Bejaia) to manufacture a new variety of brick. The principle consists in varying the percentage of these wastes and the firing temperature. Methodology. After mechanical preparation in the laboratory, which consists of crushing, grinding and sieving operations, the two materials of phosphate and clays are characterized by several analysis techniques (XRD, IR and XRF). The brick manufacturing tests from these two materials were carried out for different weight percentages and for different firing temperatures. Findings. The combination of these two materials constitutes a new approach to the recovery of natural phosphates, which has a very high waste rate. Tests of making bricks from these two materials have yielded promising results. From a mechanical point of view, the best flexural strengths obtained at a temperature of 900 C vary from 3 to 5 MPa depending on the type of phosphate/clay mixture. The same goes for the compressive strength, which varies from 15 to 27 MPa depending on the type of mixture as well. These results conform to ASTM-C674, 1999 construction standards. Originality. The use of natural phosphate wastes from Djebel Onk in various proportions has resulted in a quality of brick that meets the international standards. Practical value. The mechanical properties of the brick made from these two materials, such as resistance to bending and compression constitutes a real significant recovery for the phosphate wastes from Djebel Onk.