| Abstract |
The extraction and processing of phosphate ores from sedimentary deposits generates large quantities of mine waste rocks, raising environmental concerns and contributing to landscape disfiguration. This study proposes an eco-friendly approach by exploring the extraction of sand from phosphate waste rocks (PWR) to mitigate the environmental impact associated with the disposal of mine wastes. The investigation focuses on the feasibility of creating masonry cement mortar by incorporating sand obtained from PWR. Three types of sand, Flint (FS), dolomitic limestone (DLS), and phosphate flint (PFS), obtained from the intercalation layers of phosphate were tested as partial replacements for reference sand at varying rates (0 %, 25 %, 50 %, 75 %, and 100 %). The sands were sieved through a 4 mm sieve and characterized to assess their geotechnical, chemical, and mineralogical properties. The toxicity characteristic leaching test analysis was conducted to ensure the environmental safety of recycled sands. Consistent mortar formulations were prepared and cured under uniform conditions. Results showed that a 25 % replacement ratio for each sand type yielded the highest 28-day compressive strengths, exceeding 30.5 MPa. Moreover, the water absorption of mortars decreased from 10.65 % to 8.39 %, 7.29 %, and 5.97 % with the incorporation of 25 % of FS, PFS, and DLS, respectively. Furthermore, toxicity tests revealed that recycled sand met the specified limits for toxic elements Ag, Hg, As, Cd, Cr, Pb, and Zn, and affirmed that incorporating these wastes into MCM significantly reduced the leaching of these metal ions to levels below detection limits (DL=0.01 mg/L). This research contributes to sustainable construction practices by providing a viable solution to minimize mine waste and reduce the construction industry's reliance on natural resources, ultimately addressing both environmental and resource-related challenges. |