Investigation of Bridge Scour Mitigation with Nature Binding Materials: Biopolymers

Abstract

The use of biopolymers to tackle geotechnical problems is an essential step toward the development of sustainable geotechnical systems. The strength and erosion resistance of biopolymer-treated Hot Coffee soil sampled from the bridge site in Jackson, Mississippi were examined in this research. The optimum biopolymer concentration and moisture content were tested for Agar Gum, Xanthan Gum, and Guar Gum treatment of Hot Coffee soil, respectively. The mechanical behavior and erosion resistance of biopolymer-treated soil samples were evaluated through the unconfined compressive strength test, splitting tensile test, triaxial test, and pocket erodometer test. The results indicated that all three biopolymers improved Hot Coffee soil strength, but Guar Gum improved soil unconfined compressive and tensile strength greatly. The addition of 1% Guar Gum can improve the unconfined compression stress (UCS) and split the tensile strength of Hot Coffee soil to roughly 4,000 kPa and 600 kPa, respectively. At the same time, the cohesion of Hot Coffee soil treated with biopolymer was enhanced. The cohesion of the soil treated with 1.5% Xanthan Gum increased from 0 to 41.5 kPa. In addition, the erosion resistance of biopolymer-treated soil was also increased. With a 1.5% Xanthan Gum addition, the erosion resistance level of Hot Coffee soil reduced from very high erodibility to medium erodibility. Therefore, biopolymers have great potential for bridge scour mitigation.