Enzyme induced carbonate precipitation with fibers for the improvement of clay soil slopes against rainfall and surface runoff erosions

In order to improve the erosion resistance of the highway embankment slopes against rainfall and surface runoff erosions, the enzyme induced calcium carbonate precipitation (EICP) technology combined with different types of fibers, including steel, glass, and Polypropylene (PP) fibers, was studied for the treatment of the cohesive soil slope surface. The treatments were applied by a two-step method. In the first step, the treatment solutions were sprayed to the soil surface. In the second step, after the cracks were fully developed, quartz sand was filled into the cracks and another round of EICP spray treatment was applied in order to repair the cracks. Soil crack image analysis, crack repair test, rainfall and surface runoff erosion test, surface penetration resistance test, moisture content measurement, and soil microstructure analysis were carried out. The results show that the EICP technology can effectively cement the soil and improve the mechanical strength and erosion resistance of the cohesive soil slope. The average penetration resistance is about 10 times that of the untreated samples. The strength and erosion resistance of the fiber-added samples were further improved after EICP treatment with the addition of fibers. Both the glass fiber- and steel fiber-added samples exhibited excellent erosion resistance under rainfall and surface runoff erosion, with the amounts of eroded particles 35.78% and 1.89%, respectively, as compared with the sample treated with EICP only. The additions of fibers did not have any negative impact on the conversion efficiency of calcium. Meanwhile, the fibers could function together with calcium carbonate to form a net structure inside the soil so as to increase the strength and the durability, and reduce the water infiltration into soil. Therefore, the EICP treated samples with steel fibers and glass fibers have better treatment effects and are recommended for further applications.

Automated summary

The study investigated the use of enzyme induced calcium carbonate precipitation (EICP) technology combined with different types of fibers to improve the erosion resistance of highway embankment slopes against rainfall and surface runoff erosions. The results showed that the EICP technology effectively cemented the soil and improved its mechanical strength and erosion resistance. Samples with glass fiber and steel fiber additions exhibited excellent erosion resistance under rainfall and surface runoff erosion.