Strengthening of Dune Sand with Sodium Alginate Biopolymer

Abstract

Improvement of soil characteristics has always been of interest to civil engineers. This research aims to propose an environmentally-friendly material to improve dune sand strength using sodium alginate biopolymer. For this purpose, unconfined compressive tests were performed. The effect of temperature on the variation of compressive strength was also studied. It was shown that curing at temperatures of higher than 45°C led to a gradually decrease of compressive strength up to 80°C. Curing time was also an effective parameter on the compressive strength which considerably increased until 7 days and samples reached to 90% of their total strength. CBR tests were also conducted to evaluate the ability of using sodium alginate for base and subbase of road stabilization. The results indicated that sodium alginate as a biodegradable material greatly increased the CBR strength in comparison to pure sand. A microstructural analysis was also carried out through SEM images which showed that sodium alginate effectively linked soil articles together through different types of chemical bonds. Consequently, it was pointed out that sodium alginate has a good potential to improve the mechanical properties of poorly graded sand, and also it has no detrimental effects on the environment.