Characterization of Moroccan coal waste (Jerada Mine): Impact on physical properties of mortars made of coal waste
Résumé
The exploitation of the mine of Jerada in Morocco generates significant quantities of waste rock stored in heaps. This study aims to exploit these mining wastes, as constituents in building materials. A first characterization work has been performed on coal waste, using mineralogical, thermal and physical tests on samples in powder form. The experimental results lead us to the possible recovery of such waste as partial replacement of cement or aggregates in mortars and concretes. An initial exploratory work was the use of coal waste as partial substitution in cementitious mortars, but the low index of activity showed that the waste does not present pozzolanic reactivity. Thus, the following study will be made on mortars with the addition of this waste as a volume replacement of sand with different percentages. In the second part, physical tests were conducted to characterize the mortars before and after heat treatment at 400°C and 600°C, by measuring the apparent density, porosity, gas permeability and the ultrasonic wave propagation. We have observed that porosity increases with the addition of waste and even with the heat treatment, resulting in a remarkably lightweight mortar. On the other hand, the measurement of the apparent gas permeability shows a decrease in permeability with the incorporation of waste. Furthermore, there is an increase of the gas permeability in mortars after thermal treatment, which is probably due to pore volume liberated by the combustion of coal. Measuring ultrasonic wave propagation shows that the sound velocity decreases with the addition of waste and with the heat treatment. This is attributed to the increase in porosity that will limit the waves' velocity. Thus, the thermal processing of these composites is interesting to obtain lightweight and insulating materials. © 2017 University of Mohammed Premier Oujda Morocco.