A COMPARATIVE STUDY ON FLEXIBLE PAVEMENTS REINFORCED WITH COIR/SYNTHETIC GEOTEXTILES

Abstract

Geosynthetics are being widely used in highway engineering, to solve a variety of problems related to drainage, separation and reinforcement. Geotextiles with natural fibres such as coir and jute are emerging as an alternative to polymeric geotextiles for application in temporary or in non-critical structures, where a shorter life span may be adequate. Wide acceptance of geotextiles with natural fibres was hitherto hindered due to their biodegradability. As of now geotextiles with natural fibres are being used in erosion control applications. In the context of sustainable development, these environmental friendly materials can be used in developing countries, since they are abundantly available and are generally lower in cost compared to their synthetic counterpart. Research on these materials is required to understand their behavior thoroughly in order that one may use them confidently. In the present study, an effort was made to increase the life of coir geotextiles by treating it with phenol. The reinforcing effect of coir was also studied. From laboratory investigations, it was found that coir geotextiles should be soaked for 4 hrs in 5% phenol solution for best results. It was observed that reduction in tensile strength was 11.8% less for phenol treated coir than untreated coir after a period of 20 days incubation which refers to a period of 60 days in field. From the plate load test results, an increase of 42% of modulus of subgrade reaction was observed by reinforcing the subgrade with coir. It was observed that there is only 8% difference in the modulus of subgrade reaction values of synthetic and coir reinforced subgrades. It was observed that, there is only 15% and 5% difference in CBR and Modulus of elasticity values of Coir and synthetic geotextile reinforced subgrades respectively. It iii was also observed that, with the placement of coir reinforcement at 16.5 cm, there is decrease in the value of modulus of subgrade reaction, CBR and elastic modulii by 30%, 14% and 13% respectively, whereas, in case of synthetic geotextile reinforcement the decrease is 30%, 14%, 18% respectively.