Flexural performance and microstructural characterization of cement-treated sand reinforced with palm fiber

Abstract

Sands are mixed with cement to create cement-treated sands (CTSs) for embankment and road materials in civil engineering works. However, CTS exhibits undesirable brittle behavior because the CTS can break suddenly after the applied stresses reach their peak strength. CTS reinforced by natural fibers is called CTSF. This paper aims to study the influence of palm fiber on the flexural performance and microscopic characterization of CTSF specimens. Palm fiber contents of 0.5, 1, and 2% by volume and fiber lengths of 10,20, and 40 mm were utilized. The four performances of CTSF are peak strength, residual strength, toughness, and equivalent flexural strength. The interaction mechanism of the CTSF fiber was examined using scanning electron microscopy. The results show that the palm fibers change the behavior of CTS from brittle to semi-ductile or ductile. The 1% fiber content and 40-mm-long fiber improve the flexural of unreinforced samples by a factor of 2.7. The best residual strength at a deflection of 2 mm is obtained from the specimen with a 2.0% fiber content and a 40 mm fiber length exhibiting the residual-peak flexural strength ratio of 1.0. All palm fiber-reinforced samples show softening behavior because an equivalent strength ratio is less than 100%. The 2% fiber content and 40 mm fiber length provide the best equivalent strength ratio since the equivalent strength ratios are enhanced by a factor of 20. The fiber content and length mainly affect the equivalent strength ratios. A single failure plane is seen for CTS and CTSF samples with low fiber content, whereas numerous cracks are observed for CTSF samples. Regarding failure mode and flexural performances, palm fiber inclusion is suitable as the base and subbase for the bound pavement structure in civil and pavement engineering works.