Mechanical behavior of silty sand reinforced with nanosilica-coated ceramic fibers

Abstract

Enhancement of the mechanical characteristics of ceramic fiber-reinforced soil samples by attaching nanosilica particles to the fiber surface has not yet been fully investigated. The present study took the novel approach of coating the ceramic fibers with nanosilica particles to improve the interfacial interaction of the fiber matrix. The results of direct shear and California bearing ratio (CBR) tests on treated soil specimens and the effects of ceramic fiber content, fiber length and nanosilica content on the mechanical behavior of silty sand are presented. The results showed that the addition of ceramic fibers to the silty sand significantly increased the shear strength and shear strain at the maximum shear stress. The dilative behavior of the soil specimens was found to decrease with the addition of ceramic fibers. The reinforced specimens with a ceramic fiber content of 1.5% and fiber length of 6 mm exhibited the highest peak shear strength. The effects of ceramic fiber content on the internal friction angle and cohesion of the reinforced specimens were dependent on the fiber length. The maximum CBR occurred at a fiber length of 18 mm. The addition of nanosilica noticeably increased the cohesion and slightly increased the internal friction angle. The improvements in the mechanical behavior of the soil after the addition of nanosilica could be attributed to its pozzolanic reaction. The addition of 1% nanosilica increased the influence of the ceramic fiber on the shear strength. In most cases, the addition of nanosilica had a negative effect on increasing the CBR of fiber-reinforced specimens.