水泥乳化沥青胶浆与RAP粘附性的量化评价

Quantitative evaluation of interfacial adhesion between cement emulsified asphalt mastic and RAP

冷再生乳化沥青混合料中存在水泥乳化沥青胶浆对回收沥青路面材料(RAP)粘附不均匀以及浸水易剥落等问题,直接影响了混合料的水稳定性等路用性能。国内外对水泥乳化沥青胶浆与RAP粘附程度多采用定性评价,缺乏便于操作且能够精确量化的测试方法。利用HCl溶液侵蚀水泥乳化沥青胶浆薄层模拟试验,运用数字图像技术对回收沥青路面材料(RAP)进行二维形状特征提取,提出了RAP表面积计算模型;同时设计了不同形状指数的RAP与水泥乳化沥青胶浆粘附性试验,并对粘附界面的胶浆用HCl溶液进行侵蚀试验,以20min内Ca2+和Mg2+的释放量表征RAP表面胶浆层的抗盐酸侵蚀性和粘附均匀性。研究结果表明:HCl对水泥乳化沥青胶浆有侵蚀特性,可腐蚀胶浆中水泥的水化产物相;集料形状指数对水泥乳化沥青胶浆平均膜厚度影响不大;RAP形状指数越大,离子释放量与粘附量的比也越大,胶浆粘附层抗盐酸侵蚀能力下降,粘附的均匀性和粘附等级变差;随着水泥与乳化沥青质量比C/EA的增加,离子的释放量先减小后增大,胶浆粘附性先增大后减小;当C/EA为30%时,离子释放量最小,粘附性最佳。

Cement emulsified asphalt mastic was easy to peel from the interface between mastic and reclaimed asphalt pavement （RAP） after soaking and the interracial adhesion was not uniform in the cold reclaimed emulsified asphalt mixtures, which directly influenced the properties of the mixtures, such as water stability. Interracial adhesion degree was usually evaluated by qualitative methods at home and abroad and easily-operated and accurately-quantified technique was desired. In this paper, HC1 solution was used to erode the lamella of the cement emulsified asphalt mastic according to a simulation test. The digital image processing technology was adopted to get the two-dimension shape forward. The coating features of RAP. The calculation model of RAP surface area was put ability test was designed between different shape factors of RAP andcement emulsified asphalt mastic; and the coating interface was eroded with HC1. HCI erosion resistance and adhesion uniformity of mastic layer were expressed by the release of Ca2＋ and Mg2＋ within 20 minutes. The results show that the HC1 has erosion characteristics for cement emulsified asphalt mastic and it can corrode cement hydrates. Aggregate shape factor has little influence on the average film thickness of cement emulsified asphalt mastic. The larger the RAP shape factor, the greater the ratio of ion release quantity to adhesion amount, the worse HCl erosion ability, the inferior the adhesion uniformity and adhesive grade. The larger the RAP shape factor, the weaker interracial adhesion of cement emulsified asphalt mastic. Ion release quantity first increases and then decreases with the increase of C/EA. However, the adhesion ability first decreases and then increases. There exists the lowest ion release quantity and the best interracial adhesion degree when C/EA reaches 30%.