Engineering Properties of Soils Reinforced by Short Discrete Polypropylene Fiber

In order to understand the engineering properties of soil reinforced by short polypropylene fiber, a series of tests were carried out to study the effect of fiber content and fiber length on the strength of the fiber-reinforced soil, as well as the effect of aggregate size and fiber additives on the engineering properties of the fiber-reinforced soil. It was shown from test results that the unconfined compressive strength (UCS), cohesion, and internal friction angle of fiber-reinforced soil were greater than those of the parent soil; the UCS, cohesion, and internal friction angle of fiber-reinforced soil exhibited an initial increase followed by a rapid decrease with increasing fiber content and fiber length, and hence the optimal fiber content and fiber length were found as 0.3% by weight of the parent soil and 15 mm, respectively, in this investigation. Similar trends were found in the parent soil and the fiber-reinforced soil that the strength declined with an increase in aggregate size and there was a critical size for aggregate breakage between 3.5 and 7.5 mm in average diameter; the presence of polypropylene fiber could effectively contribute to the increases in the strength and stability of the parent soil.