Workability & mechanical properties of the single and hybrid basalt fiber reinforced volcanic ash-based cement mortars after freeze–thaw cycles

Abstract

This study examines the workability, mass loss, relative dynamic modulus of elasticity (RDME), residual compressive strength (RCS), and residual flexural strength (RFS) of single and hybrid basalt (BA) fiber-reinforced cement (BAFRC) mortars after freeze–thaw (F-T) cycles. Volcanic ash (VA) was used in all mixtures by replacing 10% with cement. Two micro and one macro-BA fiber were added to cement mortars as single and hybrid forms at 0.5% and 1% volume. All specimens were exposed to 24, 48, and 72F-T cycles in a 3% sodium chloride (NaCl) solution. The changes in the microstructural properties of control and BAFRC specimens after F-T cycles were also examined with scanning electron microscope (SEM) analysis. The results showed significant decreases in all specimens’ mass loss, RDME, RCS, and RFS values after F-T cycles. Although the single and hybrid-BA fibers significantly reduce the workability of the mortars, they are slightly effective in increasing the RCS and RFS capacities of the mortars after F-T cycles. Furthermore, BA fibers contribute a little to reducing the mass losses of the mortar after F-T cycles. In addition, the hybrid use of BA fibers is more effective than single BA fibers in increasing mortars’ RCS and RFS capacities after F-T cycles, as they provide a more robust fiber/matrix interface.