季冻区橡胶沥青及混合料的路用性能研究

发布时间：2018-07-21 11:43

【摘要】：黑龙江省季冻区春、秋季节持续时间短,冬季漫长寒冷,夏季炎热多雨。针对黑龙江省季冻区的气候特点,以针入度、软化点、延度、弹性恢复及粘度为控制指标,研究橡胶沥青各技术指标随拌合温度、胶粉细度、胶粉掺量三因素的变化规律,以矿料间隙率、粗集料间隙率、沥青饱和度等体积指标为参考,对不同因素下的混合料进行配合比设计,得出级配、胶粉细度、胶粉掺量三因素对体积指标的影响规律；然后将不同因素水平条件下的混合料路用性能进行对比,分析研究了适用于黑龙江省季冻区的橡胶沥青混合料影响因素水平范围；基于季冻区昼夜温差大的特点,采用以24小时为一个冻融循环周期的冻融实验,以拉伸应变、劈裂强度及劲度模量为控制指标,研究不同空隙率、不同冻融次数条件下的橡胶沥青混合料性能的衰减规律。研究结果如下：1、橡胶沥青性能随拌合温度的升高呈抛物线式变化,温度偏高,橡胶沥青的弹性恢复较差,胶粉与沥青的反应过程存在最佳温度；胶粉粒径大,橡胶沥青低温抗拉性能差,随粒径的减小,橡胶改性沥青性能逐渐提高,但性能提高幅度逐渐减小；胶粉掺量高的橡胶沥青弹性恢复率降低,黏度较大,导致混合料压实困难,掺量低性能改善效果较差。2、采用了5种依次由粗到细的间断级配,结果发现随细集料的增加混合料粗集料间隙逐渐增大,为使粗集料形成嵌挤的骨架结构,SMA-10橡胶沥青混合料关键筛孔(2.36mm)通过率存在最高限值,但粗级配的矿料间隙率偏大,相应的沥青用量偏高。随胶粉粒径及胶粉掺量的增大,混合料的沥青用量也增大,胶粉粒径对混合料油石比的变化影响较小,混合料的油石比极差为较小。3、橡胶沥青混合料的路用性能随油石比、胶粉细度、胶粉掺量的增加而提高,但随着胶粉掺量的增加,混合料的高温性能与低温性能存在拐点,超出拐点后性能反而下降；随着细集料的增加,混合料的高温性能降低,低温性能与水稳性能提高。橡胶沥青混合料的路用性能较基质沥青混合料有较大提高,动稳定度比基质沥青混合料高出2倍左右。4、对于冻融实验,研究发现：随冻融次数的增加混合料试件的空隙率增大,劈裂强度逐渐减小；随着空隙率的增大混合料性能衰减速率加快,强度衰减幅度可高达50%,针对季冻区,为预防冻融产生的病害,应避免混合料的现场空隙率落入冻融损坏区。
[Abstract]:In the seasonal frozen area of Heilongjiang Province, the autumn season lasts for a short time, the winter is long and cold, and the summer is hot and rainy. In view of the climatic characteristics of seasonal freezing area in Heilongjiang Province, taking penetration, softening point, ductility, elastic recovery and viscosity as control indexes, the variation law of each technical index of rubber asphalt with mixing temperature, fineness of rubber powder and content of rubber powder was studied. Based on the volume index of mineral aggregate, coarse aggregate, asphalt saturation and so on, the proportion of mixture under different factors is designed, and the influence law of gradation, fineness of rubber powder and content of rubber powder on volume index is obtained. Then the road performance of the mixture under different factor levels is compared, and the influence factor range of rubber asphalt mixture suitable for seasonal freezing area in Heilongjiang Province is analyzed and studied, which is based on the characteristics of large diurnal temperature difference in seasonal freezing area. Taking 24 hours as a freeze-thaw cycle experiment and taking tensile strain, splitting strength and stiffness modulus as control indexes, the attenuation law of rubber asphalt mixture performance under different voids and different freeze-thaw times was studied. The results are as follows: 1. The performance of rubber asphalt varies parabola with the increase of mixing temperature, the temperature is high, the elastic recovery of rubber asphalt is poor, the reaction process between rubber powder and asphalt has the best temperature, the particle size of rubber powder is large, The low temperature tensile resistance of rubber asphalt is poor, and with the decrease of particle size, the performance of rubber modified asphalt is gradually improved, but the range of performance improvement is gradually reduced, the elastic recovery rate of rubber asphalt with high content of rubber powder is reduced, and the viscosity of rubber asphalt decreases, which leads to the difficulty of compaction of the mixture. The improvement effect of low content and low performance is poor. 2. Five discontinuous gradation from coarse to fine are adopted. The results show that the gap of coarse aggregate increases with the increase of fine aggregate. In order to make coarse aggregate form an embedded skeleton structure, the pass rate of critical sieve hole (2.36mm) of rubber asphalt mixture (SMA-10) has the highest limit value, but the clearance ratio of coarse gradation mineral aggregate is too large, and the corresponding asphalt content is on the high side. With the increase of rubber particle size and rubber powder content, the asphalt content of the mixture also increases. The rubber particle size has little effect on the change of the asphalt ratio of the mixture. The difference of the asphalt ratio of the mixture is smaller than that of the asphalt mixture, and the road performance of the rubber asphalt mixture varies with the asphalt ratio. The fineness of rubber powder and the content of rubber powder increase, but with the increase of the content of rubber powder, the high temperature and low temperature properties of the mixture have inflection point, and the performance of the mixture decreases after it exceeds the inflection point, and with the increase of fine aggregate, the high temperature performance of the mixture decreases. Low temperature performance and water stability are improved. The pavement performance of rubber asphalt mixture is greatly improved than that of base asphalt mixture, and the dynamic stability of rubber asphalt mixture is about 2 times higher than that of base asphalt mixture. For the freeze-thaw experiment, it is found that with the increase of freeze-thaw times, the void ratio of the mixture specimen increases. The splitting strength decreases gradually with the increase of void ratio, and the attenuation range of strength can be as high as 50%. In order to prevent the disease caused by freezing and thawing, the in-situ void rate of mixture should be avoided from falling into freeze-thaw damage zone.
【学位授予单位】：东北林业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：U414

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