基于CT技术的冷再生混合料冻融环境下损伤分析  

Damage analysis of cold recycled mixture under freeze-thaw environment based on CT technology

作　　者：王石 赵宪锋[1] 米弘泽 WANG Shi;ZHAO Xianfeng;MI Hongze(School of Civil Engineering,Lanzhou Jiaotong University,Lanzhou 730070,China)

机构地区：[1]兰州交通大学土木工程学院,兰州730070

出　　处：《复合材料学报》2022年第4期1692-1700,共9页Acta Materiae Compositae Sinica

基　　金：国家自然科学基金青年基金(11302091)。

摘　　要：通过室内实验揭示冻融环境下水泥稳定冷再生混合料细观结构的损伤演化规律,并分析水泥和旧路面沥青材料(RAP)在不同的冻融循环时期对其损伤的影响。使用CT机对冻融循环后的试件进行扫描,获得二维断层扫描图像。利用图像处理技术对扫描断面进行分析,并以图像中CT均值的变化为基础引入损伤变量。研究结果表明:随着冻融循环次数n的增加,混合料断面的CT均值呈现出先增大后减小的变化规律;损伤变量则表现出先减小后增大的变化趋势,反映出了冻融环境下水泥稳定冷再生混合料从初始细观损伤到宏观破损的全过程,可分为4个阶段:即N≤1、1<N≤3、3<N≤7和7<N≤9,且在N小于7次时水泥含量对试件损伤有显著影响,水泥可提高混合料的粘结性及早期强度;大于7次时试件的损伤主要受到RAP掺量的影响,过高的RAP含量会加剧混合料的损伤。The development of meso-damage of cement stabilized cold recycled mixture under freeze-thaw environment was revealed by indoor test,and the effects of cement and recycled asphalt pavement material(RAP)on its damage in different freeze-thaw cycles were analyzed.The specimen after freeze-thaw cycle was scanned by CT machine,and the batch of 2D slice images were obtained.The cross section was analyzed by using the image processing technology,and the damage variable was introduced based on the change of the CT mean value in the image.The results show that with the increase of the number of freeze-thaw cycles,the average CT of mixture cross section increases at first and then decreases.On the other hand,the damage variable first decreases and then increases,which reflects the whole process of cement stable cold recycled mixture from initial meso damage to macroscopic damage in freeze-thaw environment,which can be divided into four stages,i.e.N≤1,1<N≤3,3<N≤7and 7<N≤9.When the number of freeze-thaw cycles is less than 7,the cement content has a significant effect on the specimen damage,and the addition of cement can improve the adhesion and early strength of the mixture.When the number of freeze-thaw cycles is more than 7 times,the damage of the specimen is mainly affected by the content of RAP,and the excessive content of RAP will aggravate the damage of the mixture。

关 键 词：再生材料 冻融循环 CT 细观损伤 旧沥青路面材料 

分 类 号：U414[交通运输工程—道路与铁道工程] TB33[一般工业技术—材料科学与工程]