Utilization of marble dust, fly ash and waste sand (Silt-Quartz) in road subbase filling materials

Large volumes of earthen materials are used in construction each year in Turkey and elsewhere. The wastes generated from these materials can be utilised in various applications including road subbase filling materials. In this study, three different types of wastes namely fly ash, marble dust and waste sand are used. These wastes were mixed with natural soils as a potential alternative filling materials in the road subbase. Two types of natural soils were replaced with 0%, 5%, 10%, 15%, 20% of fly ash, marble dust and waste sand. Standard compaction, permeability and saturated California Bearing Ratio (CBR) tests, X-Ray Diffraction (XRD) and Scanning Electron Microscopy (SEM) analysis were performed on two types of natural soils, containing three industrial waste types in different ratios. The study indicates that the fly ash, marble dust and waste sand are fairly good additive materials in road subbase fill and reaction substantially improves their CBR, swelling ratio and water conductivity. It was found that a clear optimum replacement level of 15% for all of these by products for medium and low plasticity type of soils.