Laboratory evaluation of the geotechnical characteristics of two waste materials: Stone powder blends with brick dust

Rapidly increasing urbanization and industrialization are results of the demand generated by the growing human population, and hence leads to a large amount of waste materials. Recycling of waste materials have become an important issue worldwide, due to reasons such as limited natural resources, increasing harmful greenhouse gas emissions, increasing landfill and disposal costs. Based on this, the geotechnical characteristics of the two major waste materials, stone powder (SP) and brick dust (BD), were investigated. In this study, geotechnical properties of mixtures obtained by adding 5%, 10%, 20%, 30%, 40% and 50% (by total dry weight of mixture) brick dust to waste stone powder were examined. This study was conducted with a comprehensive test program. The addition of brick dust has a dramatically reducing effect on compression index (cc) and swelling index (cs). It was observed that the particle size of the brick used in the California Bearing Ratio (CBR) tests have a critical role on the experiment results. The results of the direct shear test showed that cohesion is the main parameter that increases the shear strength. In general, the maximum dry density decreased with the addition of brick dust, while the optimum moisture content increased. SP blend with addition of 5% BD had the highest unconfined compressive strength value while SP blend with addition of 30% BD had the lowest value. Lastly, the use of waste materials has significantly reduced the cost of base course construction compared to traditional natural aggregate.