Sustainable use of stabilized flood mud as subgrade soil for low volume traffic roads

This research was carried out to identify the basic properties of flood mud and the efficiency of biomass silica (SH85) as a stabiliser to improve the strength of this mud. Unconfined Compressive Strength (UCS) testing was carried out on untreated soil and soil treated with 2%, 4%, and 9% SH85 at three and seven curing days. The microstructure of SH85 treated flood mud was investigated via field-emission scanning electron microscopy (FESEM) and Energy-Dispersive X-Ray spectrometry (EDX) analyses. It was found that the strength of treated soil increases two to seven times that of the untreated soil strength where the highest strength was recorded at 949 kPa after the soil had been treated with 9% of SH85 for seven days. A polynomial trend was observed with an R2 greater than 95% relationship between SH85 content versus UCS, with different curing periods. The seven-day UCS of SH85 treated flood mud meets the strength requirement of 0.8 MPa for Malaysian subgrade material of low traffic volume roads and the compressibility was significantly reduced when SH85 content was greater than 4%. It was found from the FESEM and EDX results that cementitious products leading to strength improvement fill the voids of the treated soil.