Polysaccharide biopolymers in sands: properties and behaviors

Abstract

Humanity’s impact on the environment has been one of growing concern in the recent years. As industries grow and globalization becomes ever present, so too has the impact on the environment. From environmental pollution to the depletion of natural resources, there are many direct and secondary effects of human activities seen in our world today. Studies have shown that there is a direct correlation between the increasing CO2 present in our atmosphere and the increase in the occurrence of geotechnical hazards in our world. As a result, ecofriendly sustainable methods of soil improvement have been studied by various researchers around the world, one of such methods is the use of biopolymers. Several studies have shown the strengthening effects of biopolymers in soils, however, an in-depth study on how the properties of these biopolymers effect the properties of soils has not been thoroughly studied. It is the objective of this study to observe the behaviors and properties of these biopolymers and see how these properties affect the properties of sands. This study focuses on polysaccharide biopolymers, specifically xanthan and gellan gum. The strength and loading behaviors of biopolymer treated sands are correlated with the physical properties of the biopolymers themselves. Additionally, two methods of enhancing the biopolymers strength in water are discussed. Results showed that xanthan and gellan biopolymers had a critical concentration at which the behaviors shifted from a hydrogel to a biopolymer film. The biopolymer’s strengthening mechanisms in sands were shown to be mostly dependent on the tensile strength provided by the biopolymer, and higher concentrations of biopolymers the strengthening efficiency was shown to be a factor of the degree of biopolymer saturation. Loading behaviors with biopolymers showed that viscosity in sands showed highly expansive behaviors and gels in sands had slight cementation effects in which the cohesion of the sands was enhanced. It was also seen that crosslinking biopolymers and the use of hydrophobic biopolymers had capabilities of enhancing the saturated strength of biopolymer treated sands.