水温荷耦合作用下沥青混凝土水损机制研究

发布时间：2018-09-11 11:46

【摘要】：随着中国高速公路事业的迅速发展，交通量的急剧增加与汽车平均行驶速度的提高等使得已建成的高等级公路出现超负荷运行状况，早期破坏大面积出现在路面上，其中水是沥青混凝土路面早期破坏的主要因素，水损坏现象是最主要、危害最大的早期损坏类型。因此，深入研究沥青混凝土路面在水温荷耦合作用下的水损坏机理，有利于进一步加深对沥青路面水损坏的认识。本文首先介绍沥青混合料在水温荷耦合作用下水损坏的相关理论，运用表面能理论，从沥青与集料的粘附性能着手，运用沥青与矿料系统的粘附模型，获得沥青与矿料系统粘附功和表面自由能的变化，并以此评价沥青与矿料之间的粘附性能；运用室内变水头柔性侧壁渗透仪测试并获得不同空隙率的沥青混合料与渗透系数之间的关系；通过浸水马歇尔、浸水飞散以及冻融劈裂试验，对沥青混合料试件在不同温度以及不同冻融循环方式条件下进行性能测试，获得水温荷耦合作用下沥青混合料水稳定性能的变化情况；此外，本研究采用CT仪对冻融劈裂前后的沥青混合料试件进行CT扫描，研究获得冻融劈裂对试件内部的损伤状况。本文的主要结论如下： ①通过沥青与集料的表面能试验，研究得出：集料的表面能远大于沥青的表面能，沥青与集料的粘附功大小受集料的影响较大，沥青与矿料粘附过程中， SBS改性沥青与玄武岩的粘附性较好，沥青与矿料系统剥落过程中， SBS改性沥青与石灰岩之间的抗剥落能力最强。 ②通过对三种沥青混合料（SMA-13、AC-16、AC-20）渗透性能试验，得出渗水系数与空隙率的大小有直接关系，都随空隙率的增大而增大，三种类型的沥青混合料渗透系数的拐点位置与沥青路面初期破坏的临界值空隙率大致相同，同为8%-9%之间。 ③通过对不同空隙率的试件进行浸水马歇尔试验、浸水飞散试验得出：随着混合料空隙率的增大，混合料试件水稳定性能受水影响程度也增大。掺入生石灰和消石灰都可以改善沥青混合料的水稳定性，当消石灰掺量为4%时效果最为理想，，掺入水泥后几乎不能提高混合料水稳定性能。 ④采用不同温度与不同冻融循环方式来研究混合料试件在不同温度影响状况下的水稳定性能，研究得出：随着温度的升高，三种沥青混合料（AC-13、AM-13、OGFC-13）试件的劈裂强度都呈逐渐减小的趋势，劈裂强度与温度呈现出良好的指数相关性，相关系数R2介于0.92到0.98之间； ⑤在对混合料试件冻融劈裂后试件内部损伤的研究中，采用CT图像技术，并得出：沥青混合料试件在冻融过程中，水对沥青胶浆与集料之间的粘结性能产生明显的破坏作用，在试件初始空隙率较大的地方劈裂后空隙明显增大，混合料试件损伤发展的位置和方向与初始空隙分布密切相关；运用损伤变量定量的描述沥青混合料在水温荷耦合作用下发生水损破坏状况。
[Abstract]:With the rapid development of China's highway industry, the rapid increase of traffic volume and the increase of average speed of automobiles, the built highway appears overload operation, early damage occurs in large areas on the pavement, water is the main factor of early damage of asphalt concrete pavement, water damage is the most important phenomenon. Therefore, in-depth study of the water damage mechanism of asphalt concrete pavement under the coupling action of water temperature and load will help to deepen the understanding of water damage of asphalt pavement.
In this paper, the theory of water damage of asphalt mixture under the coupling action of water temperature and load is introduced firstly. Based on the theory of surface energy and the adhesion performance between asphalt and aggregate, the change of adhesion energy and surface free energy between asphalt and aggregate is obtained by using the adhesion model of asphalt and aggregate system. The performance of asphalt mixtures with different void fractions was tested by indoor variable head flexible sidewall permeameter, and the relationship between permeability coefficient and asphalt mixtures with different void fractions was obtained. In addition, CT scans of asphalt mixtures before and after freeze-thaw splitting were carried out by using a CT scanner to study the damage of asphalt mixtures caused by freeze-thaw splitting.
The main conclusions of this paper are as follows:
(1) Through the surface energy test of asphalt and aggregate, it is concluded that the surface energy of aggregate is much greater than that of asphalt, and the adhesion work between asphalt and aggregate is greatly influenced by aggregate. In the process of adhesion between asphalt and aggregate, the adhesion between SBS modified asphalt and basalt is better, and SBS modified asphalt and stone is better during the peeling process of asphalt and aggregate system. The anti stripping ability of limestone is the strongest.
(2) Through the permeability test of three kinds of asphalt mixture (SMA-13, AC-16, AC-20), it is concluded that the permeability coefficient is directly related to the void ratio, and increases with the void ratio. The inflection point of the permeability coefficient of the three types of asphalt mixture is approximately the same as the critical value of void ratio of initial damage of asphalt pavement, which is between 8% and 9%.
(3) Marshall immersion test was carried out on the specimens with different void fraction, and the results showed that with the increase of void fraction of the mixture, the water stability of the specimens increased. The water stability of the asphalt mixture could be improved by adding quicklime and lime, and the effect was most reasonable when the content of lime was 4%. It is thought that mixing cement can hardly improve the water stability of the mixture.
The results show that with the increase of temperature, the splitting strength of three kinds of asphalt mixtures (AC-13, AM-13, OGFC-13) decreases gradually, and the splitting strength and temperature show a good exponential phase. The correlation coefficient R2 ranged from 0.92 to 0.98.
_In the study of internal damage of asphalt mixture specimens after freeze-thaw splitting, CT image technology was used, and it was concluded that: during freeze-thaw process, water had a significant destructive effect on the bond between asphalt mortar and aggregate, and the voids increased obviously after splitting at the place with larger initial void ratio, and the voids of asphalt mixture specimens increased significantly. The location and direction of damage development are closely related to the initial void distribution, and the damage variable is used to quantitatively describe the water damage of asphalt mixture under the coupling action of water temperature and load.
【学位授予单位】：重庆交通大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：U414

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