Investigation of some geotechnical properties of clay/lime mixtures modified with a biopolymer

This thesis aims to improve clay soil with high plasticity and to investigate the freeze-thaw behavior of the improved soil. A natural polymer type known as sodium alginate biopolymer and lime were applied to improve the clay soil. The synergistic effects of these additives were investigated by adding lime and sodium alginate to the clay soil separately and together. The samples were enhanced by using 0%, 2%, 4%, and 6% as lime ratios, and 0%, 0.5%, 1%, and 1.5% as biopolymer ratios were kept for 7 and 28 days of curing. At the end of the curing process, the unconfined compressive strengths of the samples were determined. The samples subjected to freeze-thaw cycles were prepared at the same ratios and were kept for 28 days of curing and then subjected to 5 and 10 freeze-thaw cycles. As a result of the experiments, it was determined that adding only lime or only sodium alginate increased the strength properties of the high plasticity clay soil. In soil samples where clay and biopolymer were applied together, it was observed that the strength had higher values and the highest strength results were obtained from samples applied with 6% lime and 1% sodium alginate. Similarly, in samples exposed to freeze-thaw cycles, it was observed that the negative effect on the strength in freeze-thaw cycles was reduced by using the additives together. As a result, sodium alginate biopolymer was able to create a positive impact on the strength both in the improvement made with lime and in freeze-thaw cycles.