Effects of basalt fiber coated with different sizing agents on performance and microstructures of asphalt mixture

Abstract Basalt fiber (BF) presents remarkable capability to enhance the performance of asphalt mixture. However, this enhancing effect is highly relied on the sizing agent coated on the basalt fiber during the production process. To further understand the effects of BF coated with different sizing agents on performance and microstructures of asphalt mixture, chopped BF coated with Polyvinyl acetate emulsion (PAE), Polyester emulsion (PE), and Polyalcohol ester emulsion (PEE), respectively were utilized to prepare the corresponding asphalt mixture samples. Then, the performance of the asphalt mixture was evaluated by wheel tracking test, low temperature bending beam test, freeze–thaw splitting test and four-point bending beam fatigue test, and the crack width of the fracture sections of asphalt mixture was quantitatively analyzed by scanning electron microscope (SEM). The surface morphology, chemical compositions, and surface energy of BF coated with the three types of sizing agents were analyzed by SEM, X-ray energy spectrum and optical contact angle measuring instrument, respectively. The results showed that compared with the neat asphalt mixture, high temperature deformation resistance, low temperature crack resistance, fatigue resistance of the asphalt mixture with BF-PAE, BF-PE and BF-PEE were improved greatly. Furthermore, the type of sizing agent did present a significant impact on the performance of asphalt mixture, and BF-PAE presented the best enhancement capability, followed by BF-PEE and BF-PE. Besides, crack width of asphalt mixture with BF was only 1/3–1/6 of that of the neat mixture, of which the mixture with BF-PAE was the narrowest. Though BF with different sizing agents had similar surface morphologies, distinct changes can be observed in the surface energy, indicating different sizing agents possessed different adhesive properties with asphalt binders. Therefore, it is necessary to select a suitable sizing agent or to develop a customized one to improve the performance of asphalt mixture with BF more effectively.