西宁盐渍土地区混凝土劣化机理试验研究  

Experimental Study of the Deterioration Mechanism of Concrete in Xining Saline Soil Area

作　　者：乔宏霞[1,2] 朱彬荣[1] 陈丁山[1] 

机构地区：[1]兰州理工大学,甘肃省土木工程防灾减灾重点实验室,甘肃兰州730050 [2]西部土木工程防灾减灾教育部工程研究中心,甘肃兰州730050

出　　处：《应用基础与工程科学学报》2017年第4期805-815,共11页Journal of Basic Science and Engineering

基　　金：国家自然科学基金项目(51168031,51468039)

摘　　要：对不同组混凝土试件在多种情况下进行了耐久性试验,结合试验数据选取试件的相对质量评价参数和相对动弹性模量评价参数作为评价指标,探究了混凝土的表观损伤特征、相对质量及相对动弹性模量的变化规律,同时对不同组混凝土试件取样进行电镜扫描、EDS能谱分析及化学成分测定,以揭示混凝土的微观结构及损伤劣化机理.研究结果表明,相对质量评价参数和相对动弹性模量评价参数能直观地表征混凝土的劣化过程;西宁盐渍土地区混凝土的破坏形式为盐分的化学腐蚀和物理结晶,化学腐蚀对混凝土劣化具有加速效应,二者相互作用使混凝土发生了严重的破坏,主要的腐蚀产物有石膏、碳酸钙及硅灰石膏,特别地在西宁盐渍土地区混凝土发现了更为危害的硅灰石膏型硫酸盐侵蚀;西宁地区现场暴露混凝土已经受到盐渍土的侵蚀,其评价参数波动性变化,经过1 230d的试验还处于劣化初期.Durability experiments of different concrete specimens were conducted under multiple conditions. Combining the experimental data, relative mass evaluation parameter and relative dynamic elastic modulus evaluation parameter were selected as evaluating indicator to investigate the surface view, relative mass and relative dynamic elastic modulus variation of concrete. Meanwhile, scanning electron microscope, energy dispersive spectrum and X-ray diffraction were used to investigate the micro-mechanism and the mechanism of deterioration. The results show that evaluation parameter can better evaluate the damage process of concrete. The failure modes of concrete in Xining saline soil area are chemical corrosion and physical crystallization. Chemical corrosion has an accelerating effect on the deterioration of concrete. Interactions of two failure mode make concrete serious disruption. Main corrosion products are gypsum, calcium carbonate and thaumasite. Especially the thaumasite form of sulfate erosion is found in Xining saline soil area. Field exposed concretes in Xining area have been eroded by saline soil. Although the evaluation parameters changes in volatility, the concretes are still in early stage of degradation after 1 230 days.

关 键 词：混凝土 盐渍土 硅灰石膏 硫酸盐侵蚀 现场暴露 劣化机理 耐久性 

分 类 号：TU528[建筑科学—建筑技术科学]