Effect of fiber characteristic parameters on the synergistic action and mechanism of basalt fiber asphalt mortar

Basalt fiber has been shown to significantly improve the performance of asphalt mixtures and extend the lifespan of roads. However, more research is needed to investigate the characteristic parameters of basalt fiber when used in asphalt mortar and asphalt mixture. In order to enhance the reinforcing effect of basalt fiber on asphalt mixture and understand how it works, this study examines the properties of asphalt mortar mixed with basalt fiber with different characteristic parameters. Nine types of basalt fibers with varying characteristic parameters were selected for this work, including three lengths (3 mm, 6 mm, 12 mm) and three diameters (7 mu m, 16 mu m, 25 mu m). The properties of asphalt mortar mixed with basalt fiber with different characteristic parameters were tested. High-temperature properties were characterized using the ZSV and MSCR tests; medium-temperature properties were characterized using the LAS test; low-temperature properties were characterized using the BBR and direct tensile tests. In addition, the effects of fiber characteristics on the viscosity, structural integrity and interfacial properties of asphalt mortar were analyzed through the bond strength test, Rigden porosity test and fiber monofilament drawing test. The results demonstrate that basalt fiber can improve high-temperature properties significantly in asphalt mortar while being greatly influenced by its characteristic parameters. Specifically, fibers with a length of 6 mm and a diameter of 7 mu m exhibit superior reinforcement effects. Fatigue life results indicate that basalt fiber enhances fatigue resistance in asphalt mortar as well; furthermore, the influence exerted by fiber characteristic parameters aligns consistently with that observed for high-temperature performance. Although the BBR test results indicate that fiber incorporation has minimal impact on its enhancement, the direct tensile test results demonstrate a significant improvement in the toughness of asphalt mortar due to fiber reinforcement. The addition of basalt fiber enhances the bond strength of asphalt mortar. According to Einstein viscosity formula, the viscosity of asphalt mortar decreases with shorter fiber lengths and larger diameters. Incorporating basalt fiber can enhance the proportion and strength of structural asphalt in asphalt mortar. When comparing fibers with equal diameter or length, an increase in either parameter initially improves the strength of structural asphalt but eventually leads to a decline. Results from monofilament fiber drawing tests and theoretical critical embedding length confirm that a 6 mm fiber length is most beneficial for enhancing the performance of asphalt mortar. Basalt fiber exhibits significant potential for improving various properties of asphalt mortar and provides a favorable reference for optimizing the selection of basalt fiber.