热老化作用下沥青胶浆的微观结构及自愈合能力试验研究

发布时间：2019-02-20 08:06

【摘要】：随着社会经济的增长,我国道路运输业呈跨越式发展。在整个城市道路和公路形成的道路网中,绝大部分是沥青路面。而沥青路面在使用初期就会出现一些微小开裂和损伤,加上周围复杂环境的影响,长期使用后,路面的疲劳寿命和性能退化。事实上,已有研究成果充分证实了沥青材料具有一定的疲劳损伤愈合能力,沥青及沥青混合料的损伤愈合性能研究得到了国外道路科研工作者的广泛关注。为了研究热老化后沥青胶浆的自愈合能力,理解其自愈合机理,本文着重考虑内蒙古地区常用的基质沥青,SBS改性沥青,胶粉改性沥青三种沥青与填料结合形成的沥青胶浆在受到外界环境影响下发生热老化后的自我修复特性,采用宏、细观力学试验手段相结合,考察沥青材料的损伤及愈合特性,并找出影响愈合的主要因素,努力寻求损伤自愈的评价指标,为沥青材料的设计和改进提供参考依据。利用原子力显微镜(AFM)反映热老化作用下沥青胶浆的微观结构变化,试验发现,基质沥青胶浆出现明显的“蜂状结构”,随老化程度的增加,“蜂形结构”逐渐变窄变长,较大的粉胶比会减弱沥青胶浆的老化程度;SBS改性沥青胶浆没有出现“蜂状结构”,老化对SBS改性沥青胶浆的影响小于基质沥青胶浆,SBS改性剂的加入会起到抑制沥青胶浆老化的作用,胶粉改性沥青胶浆表面粗糙,没有出现“蜂形结构”,长期老化后呈现出分子聚集、缔合的现象。利用动态剪切流变仪(DSR)对沥青胶浆进行疲劳测试和疲劳—愈合—再疲劳试验,并采用愈合率和能量法两种方式评价自愈合性能,结合徕卡显微镜对自愈合情况进行细观观测。试验结果表明,经过热老化之后沥青胶浆疲劳寿命增加,改性沥青胶浆具有更好的抗疲劳性能,适当增加粉胶比有助于改善沥青胶浆的抗疲劳性能。基质沥青胶浆和SBS改性沥青胶浆的自愈合性能优于胶粉改性沥青胶浆,在损伤较小的情况下,愈合温度越高,间歇期越长,自愈合效果越好,粉胶比为1.5时,愈合效果最差,老化会降低沥青胶浆的自愈合效果。利用弯曲梁流变仪(BBR)对沥青胶浆进行低温弯曲流变试验和热诱导自愈合试验,结果表明,对沥青胶浆低温流变性能影响最大的是粉胶比,其次是沥青种类,老化程度的影响程度较小,增大粉胶比和发生热老化都会降低沥青胶浆的低温抗裂性能,且随粉胶比的增大,老化程度的加深会使自愈合效果变得更差。愈合温度越高,愈合时间越长,沥青胶浆的自愈合效果越好,胶粉改性沥青胶浆具有更好的低温性能和自愈合性能。建议寒冷地区选用粉胶比较小的胶粉改性沥青胶浆作为路面材料。
[Abstract]:With the growth of social economy, the road transportation industry of our country develops by leaps and bounds. In the road network formed by the whole city road and highway, the vast majority are asphalt pavement. However, there will be some minor cracking and damage in the initial use of asphalt pavement, and the influence of the surrounding complex environment will lead to the degradation of the fatigue life and performance of the pavement after a long period of service. In fact, the existing research results have fully confirmed that asphalt materials have a certain ability of fatigue damage healing. The research on damage healing performance of asphalt and asphalt mixture has been widely concerned by foreign road researchers. In order to study the self-healing ability of asphalt paste after heat aging and to understand its self-healing mechanism, this paper focuses on the base asphalt, SBS modified asphalt, which is commonly used in Inner Mongolia. The self-repairing properties of asphalt mortar formed by three kinds of asphalt modified by rubber powder and filler after thermal aging under the influence of external environment were studied. The damage and healing characteristics of asphalt material were investigated by means of macro and meso-mechanical test. The main factors affecting healing are found out, and the evaluation index of self-healing of damage is sought, which provides a reference for the design and improvement of asphalt materials. Atomic force microscope (AFM) (AFM) was used to reflect the microstructure changes of asphalt mortar under thermal aging. It was found that the "bee shaped structure" appeared obviously in the matrix asphalt mortar, and the "bee shaped structure" became narrower and longer with the increase of aging degree. Larger powder / binder ratio will weaken the aging degree of asphalt mortar. There is no "bee structure" in SBS modified asphalt slurry, and the effect of aging on SBS modified asphalt slurry is less than that on SBS modified asphalt slurry. The addition of SBS modifier can inhibit the aging of asphalt slurry, and the surface of SBS modified asphalt slurry is rough. There is no "bee-shaped structure", the phenomenon of molecular aggregation and association appears after long-term aging. The dynamic shear rheometer (DSR) was used to test the fatigue of asphalt mortar and to evaluate the self-healing performance by means of healing rate and energy method. The self-healing was observed with Leica microscope. The results show that the fatigue life of modified asphalt mortar increases after thermal aging, and the fatigue resistance of modified asphalt mortar is improved by increasing the ratio of powder to binder. The self-healing performance of matrix asphalt paste and SBS modified asphalt slurry is better than that of rubber powder modified asphalt mortar. When the damage is small, the higher the healing temperature, the longer the interval, the better the self-healing effect, and the better the ratio of powder to binder is 1.5. The healing effect is the worst, and aging will reduce the self-healing effect of asphalt paste. The low temperature bending rheological test and heat-induced self-healing test of asphalt mortar were carried out by using (BBR). The results showed that the ratio of powder to binder was the most important, followed by the kind of asphalt, on the rheological properties of asphalt mortar at low temperature. The effect of aging degree is small, increasing the ratio of powder to binder and thermal aging will reduce the low temperature crack resistance of asphalt mortar, and with the increase of the ratio of powder and binder, the effect of self-healing will become worse with the increase of the ratio of powder and binder. The higher the healing temperature, the longer the healing time, the better the self-healing effect of asphalt paste, and the better the low-temperature and self-healing properties of asphalt mortar modified by rubber powder. It is suggested that the bitumen modified by powder in cold area should be used as pavement material.
【学位授予单位】：内蒙古工业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：U414

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