Effect of Varying Curing Conditions on the Strength of Biopolymer Modified Sand

Recently, the improvement of the engineering properties of soil has been centered on using sustainable and eco-friendly materials. This study investigates the efficacy of three biopolymers: Acacia, sodium alginate, and pectin, on the unconfined compressive strength (UCS) of dune sand. The UCS test measured the effects of the biopolymer type and concentration, curing intervals and temperature, and moisture loss. The changes in the morphology caused by the biopolymer addition were examined via scanning electron microscopy (SEM). Results indicate that the UCS of the biopolymer-modified sand increased with biopolymer concentration and curing intervals. Varying the curing temperature from 25–110 °C, slightly affected the strength of the acacia-modified sand specimen, increased that of the sodium alginate-modified sand specimen up to a temperature of 85 °C, and continued to decrease that of the pectin-modified sand specimen as the temperature was increased from 25 to 110 °C. The SEM images indicated that the biopolymer’s presence within the sand pores significantly contributed to the strength. Bond decomposition occurs at temperatures greater than 110 °C for sodium alginate and pectin-modified sands, whereas bonds remain stable at higher temperatures for the acacia-modified sand. In conclusion, all three biopolymers show potential as robust and economic dune stabilisers.