Abstract
Fiber length is a key parameter for the mixture design of basalt fiber-reinforced hot mix asphalt (HMA), which significantly affects the mix performance. To evaluate the suitability of fiber lengths for HMA with different nominal maximum aggregate size (NMAS), basalt fiber with the lengths of 3, 6, 9, 12, and 15 mm were selected for dense graded gradations with different NMASs (namely, SUP-13, SUP-20, and SUP-25), so as to prepare the fiber-reinforced HMA mixtures. Then, the mix performance was evaluated by an indirect tensile asphalt cracking test (IDEAL-CT), a four-point bending beam fatigue test, a wheel tracking test, a uniaxial penetration test, a low temperature bending beam test, and a freeze-thaw splitting test. Based on the performance results, the optimum fiber length for each mix gradation was proposed by the normalization method. The results showed that adding basalt fiber can enhance the comprehensive performance of all three types of HMA to a great extent. Furthermore, fiber length presented remarkable impact on the crack resistance, the fatigue resistance of the HMA, and the low temperature crack resistance, but it had limited influence on the high temperature deformation resistance, and water stability. The optimum fiber length for SUP-13, SUP-20, and SUP-25 was 6, 9, and 12 mm, respectively.
Highlights
The explanation could be that basalt fiber works as a “bridge”, so as to effectively prevent the crack initiation and propagation process in the asphalt mixture, which is consistent with the results from reference [3]
The optimum fiber length is closely related to the nominal maximum particle size of the asphalt mixture, and larger nominal particle sizes require longer fibers
The explanation could be that basalt fiber works as a “bridge”, so as to effectively prevent the crack initiation and propagation process in the asphalt mixture, which leads to the increase of failure strain and a decrease of the flexural stiffness modulus, which is consistent with the results from reference [24]
Summary
Owing to increases in traffic volume and the number of heavy vehicles, as well as influences from environmental factors, asphalt pavement often suffers from premature deterioration far before its design life, such as cracking (especially in winter) and rutting (especially in summer) [3], seriously affecting the pavement performance, traffic comfort, and safety [4,5,6]. Introducing fibers into the HMA has proved to be an effective way to improve the mechanical and functional performance of the asphalt mixture, and it prolongs the fatigue life of the pavement structure [7,8,9,10,11,12]. Researches on the use of fibers in HMA date back to the 1950s, when asbestos fiber was first used to enhance the performance of asphalt mixture; it was replaced by polyester fibers because of environmental pollution and health hazards [13]. Polyacrylonitrile, lignin, brucite, glass, and steel fibers are currently commonly used as an alternative to deal with the main asphalt pavement
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