Investigation of the basalt fiber type and content on performances of cement mortar and concrete

Abstract

Basalt fiber (BF), a naturally recyclable material, has attracted a lot of research in the field of civil engineering in recent years as the idea of sustainable development has gained traction. However, the surface of basalt fiber is smooth, and the bonding force with the cement matrix is insufficient, making popularizing and using basalt fiber-reinforced cement-based products challenging. In this study, a bundle spliced basalt fiber (BSBF) with strong bonding force, good dispersion, and two kinds of SCBF (SCBF-Ⅰ and SCBF-Ⅱ) with surface modifiers were selected. The properties of BF and BF-reinforced cement mortar were tested, and the optimum content of BSBF with a length of 12 mm (BSBF-12) was determined by concrete performance tests.The results showed: The tensile strength of BSBF decreases after alkali corrosion, but it can still maintain a high level. BSBF has a significant benefit over SCBF in terms of increasing the early strength and flexural toughness of cement mortar. BSBF-12 was selected for a late-stage concrete test investigation. The slump of the concrete progressively reduces as the BSBF-12 content increases, and the mechanical properties reveal a trend of first rising and then reducing. The optimal BSBF-12 content is 0.3 vol%, which increases compressive strength, split tensile strength, flexural strength, and bending toughness index of concrete by 10.39%, 61.16%, 13.33%, and 50.85%, correspondingly. Furthermore, various BSBF-12 contents improve the durability of the concrete to differing degrees.