Sisal Fiber Reinforcement of EICP-Treated Soil

Sisal fibers were employed to enhance the performance of soil treated by enzyme induced carbonate precipitation (EICP). In EICP, free urease enzyme is used to catalyze the reaction between calcium chloride and urea that induces calcium carbonate precipitation in soil. The precipitation changes the mechanical properties of the treated soil through binding particles together, roughening particle surfaces, and filling pores. A laboratory study was conducted to investigate the effect of the addition of sisal fibers, including fiber ratio (as a percentage of the dry mass of fibers and sand) and the length of fiber, on the strength and ductility of EICP-improved soil. Two different lengths (10 and 20 mm) of sisal fibers were added at fiber ratios of 0 (control), 0.2, 0.3, 0.4, 0.75, and 0.85% to create specimens for unconfined compression strength tests. The optimal fiber ratio and fiber length with respect to the UCS were 0.3% and 10 mm, respectively. The UCS strength of EICP-Treated sand at the optimum fiber content was four times higher than that of the control sample. The strain at failure (peak strength) was too variable to draw any conclusions regarding ductility.