玉米秸秆纤维沥青混合料路用性能及机理分析

为分析玉米秸秆纤维沥青混合料路用性能及纤维作用机理,首先采用高速剪切法对"除芯"的饱水玉米秸秆破碎处理,通过提取比例及吸油倍数指标优选得到纤维最佳制备工艺,并对其基本技术性能进行分析;然后分别评价无纤维、木质素纤维和玉米秸秆纤维沥青混合料的高温稳定性、水稳定性、低温抗裂性及高温抗剪性;最后应用红外光谱分析纤维与混合料的键合作用,利用扫描电镜从微观角度揭示两者之间的作用机理。结果表明：玉米秸秆纤维最佳制备工艺为长度10±2 mm秸秆皮浸泡4 h后,在29 000 r·min^-1转速下破碎2 min;玉米秸秆纤维、木质素纤维沥青混合料动稳定度均提升20%左右、弯拉应变均增加3.5%左右;木质素纤维、玉米秸秆纤维沥青混合料光谱图为纤维分别与沥青混合料光谱图的叠加,加入纤维后并没有产生表征新化合物出现的波峰,纤维与混合料主要依靠物理黏结作用结合在一起;玉米秸秆纤维表面更加粗糙、长径比更大、更容易分散均决定了其改善效果优于木质素纤维,纤维对沥青的吸附作用能够降低混合料的温度敏感性,纤维的无规则分布在混合料内形成三维网状结构,具有串联骨架功能,在沥青混合料初始开裂时起到拉伸作用,阻止裂缝进一步扩展。

Analysis of Road Performance and Fiber Mechanism for Corn Stalk Fiber Asphalt Mixture

To analyze the road performance and fiber mechanism of a corn straw fiber asphalt mixture, water-saturated and decored corn straw were broken using the high-speed shearing method. The optimum preparation process of the fiber was determined according to the extraction ratio and oil absorption, and its basic technical performance was analyzed. The high-temperature stability, water stability, low-temperature crack resistance, and high temperature shear resistance of asphalt, lignin fiber asphalt, and corn straw fiber asphalt mixtures were evaluated. Finally, the bonding action between the fiber and asphalt mixture was analyzed using infrared spectroscopy and the bonding mechanism determined from the microcosmic angle. The optimum preparation process of corn straw fiber was as follows:10±2 mm long straw skin soaked for 4 h, then broken for 2 min at 29 000 rpm. The dynamic stability of the corn straw fiber asphalt and lignin fiber asphalt mixtures increased by 20% and their flexural strains decreased by 3.5%. The spectral images of the lignin fiber asphalt and corn straw fiber asphalt mixtures are superpositions of the spectra of the two kinds of fibers and asphalt mixtures. After adding fiber, no wave peaks originating from newly generated compounds were observed. The fiber and asphalt stick together due to physical bonding. The improvement of the corn straw fiber properties was more significant than that of the lignin fiber, due to its rough surface, larger diameter ratio, and easier dispersion. The temperature sensitivity of the mixture was decreased by adsorption of the fiber on asphalt and the random fiber distribution formed a three-dimensional network structure in the mixture. The series of frameworks and their associated tensile effect prevented cracks from expanding further when initial cracking of asphalt mixture occurred.