沥青路面再生方法的试验研究[D]

为了解决不同环境因素对路面工程中未经压实的再生沥青混合料(recycled asphalt mixture, RAP)老化程度影响的问题,以松散的再生沥青混合料为研究对象,利用特制的室内模拟老化试验装置,通过控制温度、湿度、老化时间、氧气浓度等因素,对新制备密级配沥青混合料AC-13进行特定环境条件下模拟老化试验. 结果表明:松散RAP混合料的老化程度随试验温度升高而增加,随空气湿度增加和氧气浓度下降而降低;不同试验温度下,沥青老化的成长速度和试验终值均不相同,表明老化过程中的化学反应因温度不同而有所差异;在通入纯氮气的试验中,沥青没有发生任何老化作用,表明沥青的老化只受氧化作用影响;环球法测软化点的试验结果对温度变化较为敏感,动态剪切流变仪(dynamic shear rheometer,DSR)测定的动态复数剪切模量在表征沥青老化程度时存在一定迟滞效应;老化后沥青混合料低温性能出现衰减,主要原因是沥青长期老化作用导致.

Experimental study on recycling methods of asphalt pavements[D].

In order to solve the problem of the influence of environmental factors on the aging of uncompacted recycled asphalt mixture (RAP), the loose RAP was taken as the research object in this paper. The aging test of newly prepared AC-13 mixture was carried out under specific environmental conditions by controlling the temperature, humidity, aging time and oxygen concentration by using a special indoor aging simulation device. The results show that the aging of loose RAP mixture increase with the increase of test temperature, while decreases with the increase of air humidity and the decrease of oxygen concentration. The growth rate and final value of asphalt aging were different at various test temperatures, indicating that the chemical reactions in the aging process vary with the temperature. In the test of pure nitrogen, the asphalt did not have any aging effect, indicating that the aging of asphalt is only affected by the oxidation effect. The ball & ring softening point test results were more sensitive to temperature changes while the results of the dynamic complex shear modulus of dynamic shear rheometer (DSR) had a certain hysteresis effect on evaluating the aging of asphalt. The low temperature performance of asphalt mixture after aging was decayed. The long-term aging effect was the main contribution to this deterioration. The findings can provide guidance and reference for indoor preparation of RAP mixture and the evaluation of aging performance of uncompacted asphalt mixture in engineering.