Selection of treated coir fabrics with oxalic acid for unpaved roads using TOPSIS technique

Abstract

Coir geotextiles due to their natural properties have significant potential in road stabilization; however, limitations like moisture absorption and degradation can constitute an obstruction in their wider application. This study focuses on developing such characteristics through oxalic acid treatment to improve mechanical properties as well as durability in the coir geotextile. 15 different samples of treated coir geotextiles with oxalic acid were prepared using the Box-Behnken design by varying concentrations, temperatures, and treatment time. Analytical Hierarchy Process (AHP) technique was used to determine the weights by creating pairwise matrix as per absolute number of priority levels for various attributes such as water absorption capacity, California bearing ratio, tensile strength, permeability, adhesion and interface friction angle. Then, the multi attribute technique i.e. technique for order preference by similarity to ideal solution method (TOPSIS), was applied to rank the various treated coir geotextiles. The best rank is achieved for coir geotextile treated with 2% oxalic acid at 35 °C for a duration of 3 h. The results of best selected treated coir geotextile and untreated coir geotextile reveals that there is reduction in water absorption capacity and permeability whereas enhancement in California bearing capacity, tensile strength, adhesion and interface friction angle, making it more suitable for road pavement applications. The FTIR and SEM analyses confirm significant surface modifications and improvements in the treated coir geotextiles.