Chemical modification of sustainable bagasse fiber and its absorption mechanism on SBS-modified emulsified bitumen

Abstract

At present, there are few reports on the application of bagasse fibers (BFs) in the pavement field, and the interaction mechanism between BFs and bitumen is still blank. In this paper, novel chemical modified BFs were introduced as sustainable additives and absorption mechanism between chemical modified BFs and styrene–butadiene–styrene (SBS)-modified bitumen was also revealed through theoretical models and experimental methods. The results show that the concentration of sodium hydroxide solution as 1.5 %, reaction temperature of 40 °C and soaking time of 100 min are the optimal experimental parameters of chemical modification. Compared to virgin BFs, the chemical modified BFs increase the oil absorption rate from 6.46 times to 8.96 times, heat loss decreases from 7.76 % to 1.65 % and total pore volume, micro-pore area and volume increase by 241 %, 170 % and 276 %, respectively. The main component of modified BFs adsorbing SBS-modified bitumen is resin and per unit mass of adsorbed resin by modified BFs decreases gradually with the increased contents of modified BFs. The equilibrium adsorption capacity calculated by quasi-second-order model is closer to the experimental results than that calculated by the pseudo-first-order model. The resin is first adsorbed by adsorption sites on outer surface of fiber, and then diffuses into interior of fiber. With the decrease of resin concentration during absorption, the gradually saturation of adsorption sites leads to weakening adsorption, which finally reaches equilibrium.