Title : Industrial by products of granular character management issues and valorization approach in Civil Engineering
Every year, billions of tonnes of waste are generated worldwide, with humanity discharging 12 billion tonnes of industrial and household waste annually. The production of this waste has increased incredibly over time due to rapid urbanisation, population growth and industrial development. Among the most abundant industrial wastes, we can mention household waste incineration bottom ash, coal ash, steel and lead slag. Indeed, about 58.4% (5357 million tonnes) of the global industrial waste rate is produced by six countries: China, Japan, India, South Korea and Australia. Landfilling of this waste. Of course, the management of these huge quantities of waste presents a great challenge to the producing countries. In addition to the gases emitted during the production process, landfilling is a direct threat to the environment, especially to water and soil. In addition, economic growth, driven by infrastructure development, requires increased demand for construction materials, especially aggregates and sand. Today, many developing countries suffer from the problem of depletion of natural aggregates, which requires the search for alternative products. Researchers have become aware of the geotechnical characteristics of some of these wastes, notably coal ash and slag, which has led to their use in civil engineering, particularly in the road sector.
Morocco has a subsoil rich in varied mineral resources spread throughout the kingdom. The main mining operations concern, among others, phosphate, coal, lead, iron, zinc, copper and nickel. There are officially 240 mining sites in the Kingdom, among which 200 are closed and abandoned. Today, several storage sites have been generated in the country, of which two are considered to be the main ones. The first storage site is located in the WEST of the country in the Jorf Lasfar industrial zone in the city of El Jadida, which contains: a large thermal power plant, a steel mill and phosphate processing units. The waste generated is mainly in the form of : Coal ash, iron slag and phosphogypsum. The second storage area is located in the east of the country near the cities of Jerada and Touissite, in addition to coal ash, the waste stored in this area is in the form of lead and zinc slag.
Our research work has proven the possibility of using these by-products in road construction. Indeed, the treatment of coal slag with lime improves its properties for use in sub-base courses, and our results show the possibility of using lead slag as a substitute for sand in asphalt and gravel. This will make it possible to meet the increased local need for aggregates while mitigating the environmental risks of landfills.