Combined Effect of Biopolymer and Fiber Inclusions on Unconfined Compressive Strength of Soft Soil

Abstract

The utilizing of traditional chemical stabilizers could improve soil engineering properties but also results in brittle behavior and causes environmental problems. This study investigates the feasibility of the combined utilization of an ecofriendly biopolymer and fiber inclusions as an alternative to traditional cement for reinforcing soft soil. A series of unconfined compression tests were conducted to examine the combined effect of the biopolymer and fibers on the stress–strain characteristics, strength improvement, failure pattern, and reinforcement mechanism of soft soil. The results show that the biopolymer associated with fibers has an unconfined compressive strength similar to that of fiber-reinforced soil. However, it then increases with different curing times and conditions, which can be up to 1.5 MPa–2.5 MPa. The combined effect of fibers and the biopolymer is not simply equivalent to the sum of the effects of each individual material. The fiber shows its role instantly after being mixed into soil, whereas the effect of biopolymer gradually appears with sample curing time. The biopolymer plays a dominant role in increasing the peak unconfined compressive strength and brittleness of soil, while the amount of fiber is crucial for reducing soil brittleness and increasing ductility. It is shown that the biopolymer not only contributes to the particle bonding force but also facilitates the reinforcement efficiency of fibers in the soil. The fibers in return assist in reducing the soil brittleness arising from biopolymer cementation and provide residual resistance after post-peak failure.

Study on the impact of a biopolymer-fiber combination on soil reinforcement

“…At the same time, the spatial network structure formed by the fibers provides a space skeleton for the biopolymer reinforced soil. When the soil is subjected to external force, the existence of the space skeleton increases the ductility and reduces the brittleness of the soil [28]. Under the coaction of biopolymer and fibers, it shows multiplying effect The schematic diagram of the interaction among biopolymer, fibers and soil particles is shown in figure 5.…”

Investigating combined effects of saturation–desaturation cycles and cyclic stress resistance of reinforced biopolymer-treated soil

“…Microorganism-based biopolymers, including xanthan gum, gellan gum, and dextran, are polysaccharides produced by Xanthomonas campestris, forming helical structures mainly composed of two glucose, two mannoses, and one glucuronic acid unit [12]. Previous studies, such as those by Chen et al [13]. Overall, the inter-particle relations and strengthening behavior of the biopolymer-soil matrices are considered suitable for subgrade treatment owing to their net-zero benefits and mechanical strength improvements.…”

Laboratory Experiments and Numerical Simulation Study of Composite-Material-Modified Loess Improving High-Speed Railway Subgrade

“…Additionally, it has been widely recognized that the improvement of soil mass by adding a variety of composite materials with a certain mixing ratio is better than that by adding a single material [ 30 , 31 ]. At present, the addition of lime-ash or cement-lime mixes to soil is the most-used method for the improvement of loess subgrade, while few studies were found on the improved materials improve loess subgrade by combining new materials with traditional materials [ 32 ].…”