Experimental study on sodium bicarbonate treated coir geotextile for enhancing subgrade stabilization

Abstract

Surface rutting and cracking have been a continuing problem on roads to date. These failures are directly attributed to poor subgrade soil quality. Hence, the potential of coir geotextile as reinforcement has been studied. Several chemical treatments were introduced on coir geotextile to improve its tensile strength further. The significant increase in the tensile strength of coir geotextile when treated with sodium bicarbonate (NaHCO3) was determined in this study. Relatively, the increase in California Bearing Ratio (CBR) on subgrade reinforced with sodium bicarbonate (NaHCO3) treated coir geotextile was determined in this study. Grab tensile strength was employed to determine the tensile strength of the untreated and treated coir geotextile having surface densities of 700g/m2 and 900 g/m2 with varying concentrations of 8wt.%, 12wt.%, and 16wt.% under 24 hours and 120 hours soaking time. The California Bearing Ratio was evaluated for the unreinforced and reinforced subgrade samples using the coir geotextile of prevailing tensile strength. It has been found that TW2-16B obtained the maximum tensile strength, which is one of the reinforcement strength factors having a surface density of 900 g/m2, 16 wt.% concentration of NaHCO3 soaked at 120 hours. Furthermore, a significant increase of 393.33% in the CBR value of treated coir geotextile reinforced subgrade was observed compared to the natural unreinforced soil. The results indicated that chemical treatment of sodium bicarbonate on coir geotextile significantly improved its tensile strength property and, hence, could have been a potential reinforcement for enhancing subgrade stabilization