Improving the Unconfined Compressive Strength of Red Clay by Combining Biopolymers with Fibers

Abstract

To explore an environmentally friendly improvement measure for red clay, the function and mechanism of xanthan gum biopolymer and polypropylene fibers on the strength properties of red clay were investigated by unconfined compressive strength and scanning electron microscopy tests. The test results demonstrated that the contents and curing ages of xanthan gum had significant influences on the unconfined compressive strength of red clay. Compared with untreated soil, 1.5% xanthan gum content was the optimal ratio in which the strength increment was between 41.52 kPa and 64.73 kPa. On the other hand, the strength of xanthan gum-treated red clay increased, whereas the ductility decreased with the increase in curing ages, indicating that the xanthan gum-treated red clay started to gradually consolidate after 3 days of curing and stiffness significantly improved between 7 and 28 days of curing. The results also showed that the synergistic consolidation effects of the xanthan gum–polypropylene fibers could not only effectively enhance the strength of red clay but also reduce the brittle failure phenomenon. The strengths of soil treated with 2.0% xanthan gum-polypropylene fibers were 1.9–2.41 and 1.12–1.47 times than that of red clay and 1.5% xanthan gum-treated clay, respectively. The results of study provide the related methods and experiences for the field of ecological soil treatment.