Improvement of engineering properties of sandy soils using biopolymer

Nowadays, several methods are used in the field of construction engineering in order to make low bearing capacity soils more suitable for receiving and supporting infrastructure. These methods are vibroflotation, sand drain, lime stabilization, cement stabilization, fly ash stabilization etc…. However, these methods are somewhat harmful and gradually contribute to the degradation of the environment. Cement is a construction material whose implementation releases a huge amount of CO2 which is harmful to the ozone layer. Given the environmental problems (pollution) facing humanity, it is necessary to find more ecological methods that will not contribute to the progressive destruction of the environment. During this experimental study, two biopolymers were used to improve the mechanical properties of fine sand collected in Adana city. These biopolymers are xanthan gum and guar gum. In order to evaluate the mechanical properties of the treated sand biopolymer, a series of laboratory tests was performed. The method consists in analyzing through laboratory tests, the shear strength resulting from the sand-guar gum and sand-xanthan gum mixture. Natural fine sand was washed, oven-dried, and then sieved using US sieve before being mixed with a solution of different concentrations of guar gum/ xanthan gum (1%, 2%, 3%, 4% and 5% of guar gum/xanthan gum). Treated sand-biopolymer mixture cylindrical samples were molded and cured for 1 day, 1 week, 2 weeks 3 weeks, and 4 weeks. Direct shear tests, unconfined compression tests, standard proctor tests, consolidation tests, permeability test, and triaxial tests were performed. According to the results of strength tests, guar gum and xanthan treatment increased significantly the shear strength of sand for certain curing time.