Experimental study on the effect of chitosan biopolymer on sandy soil stabilization

Abstract

Due to the environmental impacts of conventional soil stabilization materials, such as cement, ongoing efforts have been carried out by different researchers to find alternative economical materials for substitution. Biopolymers are environmentally friendly materials that are widely used in different geoenvironmental applications such as removal of heavy metals from contaminated soils, reduction of soil hydraulic conductivity, erosion control, and soil improvement. In this research the feasibility of using chitosan biopolymer for sandy soil stabilization has been studied. The effects of biopolymer content, curing time, and curing conditions have investigated using unconfined compression tests. The results indicated that incorporation of chitosan has the potential to increase the interparticle cohesion between the particles and considerable improvement of sandy soil mechanical properties. After initial strengthening of the soil, some strength reduction over time was observed due to the degradation characteristics of the chitosan. With regards to the curing condition, better performances at dry condition compare to the wet and saturated environment were achieved. In addition to soil mechanical properties, the pore plugging effect of chitosan biopolymer on highly permeable sandy soil has been studied in this study.

The Effects of Particle Size Distribution and Moisture Variation on Mechanical Strength of Biopolymer-Treated Soil

“…Biopolymers increase the soil water retention capacity and, therefore, aid vegetation growth [ 10 , 11 , 12 , 13 ]. The compressive and shear strength properties of problematic soils have been significantly improved by adding various biopolymers, such as agar, xanthan, chitosan, alginate, and gellan gum [ 14 , 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 , 25 ].…”

“…In view of the life cycle assessment for comparing the use of biopolymers and other conventional materials in a geotechnical project, biopolymers outperform conventional polymers considering the climate impact. Even though energy and water should be supplied during the synthesis and transportation of biopolymers, by using biopolymers the environmental impacts are reduced by approximately 85% compared with conventional polymers, and the impacts are significantly lower than those of traditional adhesives such as cement and lime [ 18 ]. In the case of agar, the conventional production process includes pre-treatment, extraction, filtration, concentration, and dehydration stages, which use very little water and leave a negligible carbon footprint.…”

“…In the case of agar, the conventional production process includes pre-treatment, extraction, filtration, concentration, and dehydration stages, which use very little water and leave a negligible carbon footprint. For alginate, its low toxicity, biocompatibility, and relatively low cost suggest that alginate is a good choice for ground improvement [ 18 ]. Alginate is produced in high amounts around the world with reliable sources [ 36 ].…”

Effect of Seawater on the Mechanical Strength of Geopolymer/Cement Stabilized Sandy Soils

“…According to previous research, an eco-friendly Portland cement substitute is required due to the insufficient mechanical qualities of Portland cement in stabilizing saline soils under marine conditions [8,9]. Geopolymers are a type of alkali activated cements used as novel construction materials in various applications [10][11][12][13]. A previous study explored the possibility of using seawater to produce alkali activated cements [14].…”

Impact of Chitosan on the Mechanical Stability of Soils

“…They observed a strong effect of soil stabilization in laboratory conditions, however, under natural conditions, the effect was observed only in the initial part of the furrow, which was explained by the very strong binding of chitosan to soil components in the area close to the zone of its application. Shariatmadari et al [ 32 ] studied the effects of chitosan dissolved in acetic acid on sandy soil stabilization by using unconfined compression tests. The unconfined compression tests conducted after 7, 14 and 28 days showed the strength of samples treated in dry conditions was higher than for samples cured in saturated water conditions.…”