The california bearing ratio (cbr) of a micaceous silt, common to the piedmont in the southeastern united states, was significantly enhanced by the addition of discrete polypropylene fiber reinforcement. Dosages of fiber ranging from 0.09 To 1.5% Of the soil's dry unit weight were used in soil compacted to 100% of its standard proctormaximum dry density. Fiber configurations consisted of monofilamentfiber of 0.38- And 0.76-Mm diameter as well as an equivalent fibrillated fiber of 0.38-Mm diameter, a lattice-work comprising smaller-diameter webs and stems. Fiber lengths were 19 and 25 mm. The addition of fiber increased the cbr values 65 to 133% over unreinforced specimens, depending on fiber configuration and dosage. Cbr values using 25-mm-long, 0.76-Mm monofilament fiber reinforcement increased significantly up to a dosage of 1%, then began to decrease. The test results indicated that there is an optimum fiber dosage as well as an optimum configuration for improving a compacted soil's cbr value. This paper appears in transportation research record no. 1295, Soil stabilization 1991 .
Abstract