Effect of Polypropylene Fiber on the Unconfined Compressive Strength of Loess with Different Water Content

Fiber-reinforced soils have been of great interest to experimenters for building foundations' strength performance, time, and economy. This paper investigates the effects of water content and polypropylene fiber dosage and length on loess's unconfined compressive strength (UCS) according to the central composite response surface design test procedure. The water content is 11%-25%, the mass ratio of fiber to soil is 0.1%-0.9%, and the fiber length ranges from 6-18 mm. The response surface method (RSM) developed full quadratic models of different variables with response values. After analysis of variance (ANOVA), the mathematical model developed in this study was statistically significant (p <= 0.05) and applicable to the optimization process. The optimization results showed that the optimal water content values, fiber amount, and fiber length were 16.41%, 0.579%, and 14.90 mm, respectively. The unconfined compressive strength of the optimized specimens was increased by 288.017 kPa. The research results can reference the design and construction of fiber-reinforced soil in practical projects such as road base engineering and foundation engineering.