冻融循环对SMA混合料性能的影响研究

发布时间：2019-05-19 12:54

【摘要】：我国的寒区和其它一些地区在秋冬季节由于温度较低、昼夜温差较大，道路经常处于结冰与融化的反复中，造成沥青路面不同程度的冻融破坏。目前专门针对沥青混合料冻融破坏的研究并不多，SMA是一种性能优良的沥青混合料，近年来得到了广泛的应用。因此，，很有必要研究冻融循环对SMA性能的影响。选择原材料并进行性能测试，设计SMA混合料的配合比、冻融循环的试验条件、试验方法。按照初始空隙率进行分组，测定混合料冻融循环后的质量损失率、空隙率、马歇尔稳定度、流值、马歇尔模数、冻融劈裂抗拉强度、冻融劈裂抗拉强度比（TSR），并提出冻融残留稳定度、冻融残留马歇尔模数两个新指标。以冻融残留稳定度和TSR达到80%的冻融循环次数来评价SMA混合料冻融循环后的水稳定性。试验结果表明，初始空隙率对SMA冻融循环后的体积性能和水稳定性的影响较大，消石灰和水泥可以显著增强SMA冻融循环后的体积性能和水稳定性，且消石灰的效果要好于水泥。确定SMA车辙板的碾压次数，成型车辙板，设计冻融循环的试验条件、试验方法。测定冻融循环后SMA车辙板的动稳定度、相对变形率和总变形量，并提出冻融残留动稳定度这一新的评价指标，以该指标达到80%的冻融循环次数来评价SMA混合料冻融循环后的高温稳定性。测定SMA车辙板冻融循环后的渗水系数，进一步探究冻融循环对SMA混合料空隙率的影响。试验结果表明：冻融循环使SMA的高温稳定性降低，渗水系数增大；掺加水泥、消石灰可以显著地改善SMA混合料冻融循环后的高温稳定性，且消石灰的效果要好于水泥；SMA车辙板的初始空隙率越大，冻融循环后的渗水系数也越大，但掺加消石灰的SMA车辙板虽然初始空隙率最大，冻融循环后的抗渗水性能却依然较好。测定冻融循环后SMA马歇尔试件的超声波速，分析试件中的水对超声波速的影响，提出了超声波速修正时间公式。建立修正后的超声波速与马歇尔稳定度、冻融劈裂抗拉强度的相关关系，提出了建议的拟合经验公式。试验结果表明：经过修正后的超声波速与冻融循环后SMA混合料的马歇尔稳定度、劈裂抗拉强度有良好的相关性。
[Abstract]:In the cold region of our country and some other areas in autumn and winter, because of the low temperature and the large temperature difference between day and night, the road is often in the repeated freezing and melting, resulting in different degrees of freeze-thaw damage of asphalt pavement. At present, there are few researches on freeze-thaw failure of asphalt mixtures. SMA is a kind of asphalt mixture with excellent performance, which has been widely used in recent years. Therefore, it is necessary to study the effect of freeze-thaw cycle on the properties of SMA. The raw materials were selected and the performance test was carried out. The mix proportion of SMA mixture, the test conditions and test methods of freeze-thaw cycle were designed. According to the initial voidage, the mass loss rate, voidage, Marshall stability, flow value, Marshall modulus and freeze-thaw split tensile strength ratio (TSR), of the mixture after freeze-thaw cycle were measured. Two new indexes, freeze-thaw residual stability and freeze-thaw residual Marshall modulus, are put forward. The water stability of SMA mixture after freeze-thaw cycle was evaluated by freeze-thaw residual stability and the number of freeze-thaw cycles with TSR up to 80%. The experimental results show that the initial voidage has a great influence on the volume performance and water stability of SMA after freeze-thaw cycle. Lime and cement can significantly enhance the volume performance and water stability of SMA freeze-thaw cycle, and the effect of lime elimination is better than that of cement. Determine the rolling times of SMA frog board, form the frog board, design the test conditions and test methods of freeze-thaw cycle. The dynamic stability, relative deformation rate and total deformation of SMA frog plate after freeze-thaw cycle were measured, and a new evaluation index of freeze-thaw residual dynamic stability was put forward. The high temperature stability of SMA mixture after freeze-thaw cycle was evaluated by 80% freeze-thaw cycle times. The water permeability coefficient of SMA rut plate after freeze-thaw cycle was measured, and the effect of freeze-thaw cycle on voidage of SMA mixture was further investigated. The experimental results show that the high temperature stability of SMA is decreased and the water permeability coefficient is increased by freeze-thaw cycle, and the high temperature stability of SMA mixture after freeze-thaw cycle can be significantly improved by adding cement, and the effect of lime elimination is better than that of cement. The larger the initial voidage of SMA frog board is, the greater the seepage coefficient is after freeze-thaw cycle. However, although the initial voidage of SMA frog board with lime is the largest, the impermeability of SMA frog board after freeze-thaw cycle is still better. The ultrasonic wave velocity of SMA Marshall specimen after freeze-thaw cycle was measured, the influence of water in the specimen on ultrasonic wave velocity was analyzed, and the formula of ultrasonic velocity correction time was put forward. The relationship between the modified ultrasonic velocity and the stability of Marshal and the tensile strength of freeze-thaw split is established, and the suggested fitting empirical formula is put forward. The experimental results show that there is a good correlation between the modified ultrasonic wave velocity and the Marshall stability and split tensile strength of SMA mixture after freeze-thaw cycle.
【学位授予单位】：湖南大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U414

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