工程科学学报，第38卷，第8期：1075-1081,2016年8月 Chinese Journal of Engineering,Vol.38,No.8:1075-1081,August 2016 D0l:10.13374/j.issn2095-9389.2016.08.005:http://journals..ustb.edu.cn 混凝土硫酸盐腐蚀损伤的声波与声发射变化特征及 机理 刘娟红四，赵力”，宋少民，纪洪广” 1)北京科技大学土木与环境工程学院，北京1000832)北京节能减排关键技术协同创新中心，北京100044 ☒通信作者，E-mail:juanhongl966@hotmail.com 摘要试验模拟干湿循环作用下混凝土受10%（质量分数）硫酸钠溶液侵蚀的腐蚀环境，测试和分析硫酸盐不同侵蚀时期 混凝土单轴压缩试验时波速和声发射的变化特征.采用环境扫描电镜和能谱仪进行微观观测并结合X射线衍射测试手段分 析受蚀混凝土的损伤机理.结果表明：受侵蚀60d和80d的试件加载初期会有较明显的压密阶段，试件受硫酸盐侵蚀和干湿 循环作用愈久，加载中波速急剧下降的突变点愈提前：受蚀40d以上的试件加载中声发射事件活跃区间较集中，在腐蚀产生 的缺陷和薄弱位置容易出现应力集中和能量集中释放，声发射事件数量急剧上升的突变点提前.通过数学模型以声发射累 积振铃计数为损伤变量建立损伤模型可以表征混凝土中环境腐蚀、荷载及损伤之间的作用关系.腐蚀阶段钙矾石与石膏的 膨胀作用和硫酸钠的结晶压在试件内部形成微破损，受蚀混凝土表现出不同宏观性能. 关键词混凝土：硫酸盐：侵蚀：超声波速度：声发射：损伤演化：微观结构 分类号TU528.31 Ultrasonic velocity and acoustic emission properties of concrete eroded by sulfate and its damage mechanism LIU Juan-hong,ZHAO Li),SONG Shao-min2),JI Hong-guang) 1)School of Civil and Environmental Engineering.University of Science and Technology Beijing,Beijing 100083,China 2)Beijing Collaborative Innovation Center of Energy Saving Emission Reduction Key Technologies,Beijing 100044,China Corresponding author,E-mail:juanhong1966@hotmail.com ABSTRACT Simulation experiment was performed on the performance of concrete exposed to sulfate attack and dry-wet cycles. Changes in ultrasonic velocity and acoustic emission activities for concrete at different erosion periods were tested by uniaxial compres- sion test.The damage mechanism was analyzed by environmental scanning electron microscopy (ESEM),energy-dispersive X-ray analysis (EDX)and X-ray diffraction (XRD).The results show that at the beginning of loading for concrete after 60 d and 80 d ero- sion,the specimen exhibits a significant compaction phase.The longer the concrete is exposed to sulfate attack and dry-wet cycles, the earlier the sudden drop in ultrasonic velocity occurs.For concrete after 40d erosion,the active zone of acoustic emission is narrow during the loading process.The problems of stress concentration and a sudden release of energy tend to occur at the weak position caused by erosion in concrete,and a sharp increase in acoustic emission events appears in advance under sulfate attack.By means of a mathematical model,the damage model of concrete was established based on the cumulative ring-down count of acoustic emission as a variable,which reveals the relations of sulfate attack,load and damage for concrete in complex underground environments.During erosion time,the expansions caused by ettringite and gypsum and the swelling of sodium sulfate crystallization result in the evolution of micro-destruction,leading to the different macroscopic properties of corroded concrete. KEY WORDS concrete:sulfates:erosion:ultrasonic velocity:acoustic emission:damage mechanisms:microstructure 收稿日期：2015-09-22 基金项目：国家自然科学基金资助项目(51174015)工程科学学报，第 38 卷，第 8 期: 1075--1081，2016 年 8 月 Chinese Journal of Engineering，Vol． 38，No． 8: 1075--1081，August 2016 DOI: 10． 13374 /j． issn2095--9389． 2016． 08． 005; http: / /journals． ustb． edu． cn 混凝土硫酸盐腐蚀损伤的声波与声发射变化特征及 机理 刘娟红1) ，赵 力1) ，宋少民2) ，纪洪广1) 1) 北京科技大学土木与环境工程学院，北京 100083 2) 北京节能减排关键技术协同创新中心，北京 100044  通信作者，E-mail: juanhong1966@ hotmail． com 摘 要 试验模拟干湿循环作用下混凝土受 10% ( 质量分数) 硫酸钠溶液侵蚀的腐蚀环境，测试和分析硫酸盐不同侵蚀时期 混凝土单轴压缩试验时波速和声发射的变化特征． 采用环境扫描电镜和能谱仪进行微观观测并结合 X 射线衍射测试手段分 析受蚀混凝土的损伤机理． 结果表明: 受侵蚀 60 d 和80 d 的试件加载初期会有较明显的压密阶段，试件受硫酸盐侵蚀和干湿 循环作用愈久，加载中波速急剧下降的突变点愈提前; 受蚀 40 d 以上的试件加载中声发射事件活跃区间较集中，在腐蚀产生 的缺陷和薄弱位置容易出现应力集中和能量集中释放，声发射事件数量急剧上升的突变点提前． 通过数学模型以声发射累 积振铃计数为损伤变量建立损伤模型可以表征混凝土中环境腐蚀、荷载及损伤之间的作用关系． 腐蚀阶段钙矾石与石膏的 膨胀作用和硫酸钠的结晶压在试件内部形成微破损，受蚀混凝土表现出不同宏观性能． 关键词 混凝土; 硫酸盐; 侵蚀; 超声波速度; 声发射; 损伤演化; 微观结构 分类号 TU528. 31 收稿日期: 2015--09--22 基金项目: 国家自然科学基金资助项目( 51174015) Ultrasonic velocity and acoustic emission properties of concrete eroded by sulfate and its damage mechanism LIU Juan-hong1)  ，ZHAO Li1) ，SONG Shao-min2) ，JI Hong-guang1) 1) School of Civil and Environmental Engineering，University of Science and Technology Beijing，Beijing 100083，China 2) Beijing Collaborative Innovation Center of Energy Saving ＆ Emission Ｒeduction Key Technologies，Beijing 100044，China  Corresponding author，E-mail: juanhong1966@ hotmail． com ABSTＲACT Simulation experiment was performed on the performance of concrete exposed to sulfate attack and dry--wet cycles． Changes in ultrasonic velocity and acoustic emission activities for concrete at different erosion periods were tested by uniaxial compres￾sion test． The damage mechanism was analyzed by environmental scanning electron microscopy ( ESEM) ，energy-dispersive X-ray analysis ( EDX) and X-ray diffraction ( XＲD) ． The results show that at the beginning of loading for concrete after 60 d and 80 d ero￾sion，the specimen exhibits a significant compaction phase． The longer the concrete is exposed to sulfate attack and dry--wet cycles， the earlier the sudden drop in ultrasonic velocity occurs． For concrete after 40 d erosion，the active zone of acoustic emission is narrow during the loading process． The problems of stress concentration and a sudden release of energy tend to occur at the weak position caused by erosion in concrete，and a sharp increase in acoustic emission events appears in advance under sulfate attack． By means of a mathematical model，the damage model of concrete was established based on the cumulative ring-down count of acoustic emission as a variable，which reveals the relations of sulfate attack，load and damage for concrete in complex underground environments． During erosion time，the expansions caused by ettringite and gypsum and the swelling of sodium sulfate crystallization result in the evolution of micro-destruction，leading to the different macroscopic properties of corroded concrete． KEY WOＲDS concrete; sulfates; erosion; ultrasonic velocity; acoustic emission; damage mechanisms; microstructure