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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.
The experiment was conducted to simulate the corrosion environment of concrete subjected to 10% (mass fraction) sodium sulfate solution under the action of wetting and drying cycles, and to test and analyze the characteristics of wave velocity and acoustic emission during the uniaxial compression tests of concrete with different sulfate phases. X-ray diffraction and X-ray diffraction were used to analyze the damage mechanism of concrete under erosion.The results showed that there was obvious compaction stage at the initial stage of 60 days and 80 days of erosion, The longer the erosion and wetting-drying cycles, the more the abrupt change point of the abrupt decrease of the mid-wave load occurred earlier. The more active acoustic emission events occurred during the loading of the specimens over 40 days, which were prone to stress concentration in the defects and weak locations of corrosion And the sudden release of energy and the sharp increase of the number of acoustic emission events advance ahead of time.The establishment of the damage model by using the cumulative ringing count of acoustic emission as the damage variable through the mathematical model can characterize the relationship between environmental corrosion, load and damage in concrete. Eutectoid and gypsum expansion and crystallization of sodium sulfate in the specimen within the micro-damage, corrosion concrete table Different macroscopic properties.