Investigation of the Kenaf fiber hybrid length on the properties of the cement-treated sandy soil

Abstract

Abstract The current study investigated the effects of cement and Kenaf fiber (KF) on sandy soil, in terms of cement content and KF content and length as the assessment values. For this purpose, several tests, including unconfined compressive strength (UCS), splitting tensile strength (STS), and ultrasonic wave velocity (UWV), were carried out. In addition, alterations of the microstructural features evaluated through a scanning electron microscopy (SEM) analysis. In the tested samples, the effect of various contents of cement (i.e., 3, and 6%) and fibers (i.e., 0, 0.25, 0.5, and 0.75%) with lengths of 8 mm and 16 mm, on the physical and mechanical properties of the cemented sand, was investigated. Moreover, the effect of simultaneous application of 8 mm and 16 mm fibers, with the ratio of 50% (8 mm) + 50% (16 mm)—Hybrid—for all the mentioned fiber contents, was evaluated. The experimental results showed that by increasing cement content, the UCS, STS, energy absorption (EA) capacity, UWV, and brittle index increase. The inclusion of randomly distributed KF to the specimens not only decreases the brittle index, elasticity modulus, and UWV but also increases the UCS, STS, and EA capacity. Also, by growing up the KF length, the UCS and STS increase, whereas the elasticity modulus decreases. Moreover, by the application of the Hybrid mixing plan, apart from that the; UCS, STS, and EA capacity increased; and the brittle index decreased compared to the specimens with 8 mm fiber, the secant modulus at 50% of peak stress (E50) and UWV increase, in comparison to specimens containing 16 mm fibers.