干湿交替作用下碱激发混凝土氯盐侵蚀性能  

Chloride Ingress into Alkali-Activated Concrete Under Drying-Wetting Cycles

作　　者：鲍玖文 张心钰 张鹏[1] 崔祎菲 魏佳楠 庄智杰 BAO Jiuwen;ZHANG Xinyu;ZHANG Peng;CUI Yifei;WEI Jianan;ZHUANG Zhijie(Department of Civil Engineering,Qingdao University of Technology,Qingdao 266033,Shandong,China)

机构地区：[1]青岛理工大学土木工程学院,山东青岛266033

出　　处：《硅酸盐学报》2022年第6期1607-1615,共9页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(51922052,51778309,51908307,U1706222)。

摘　　要：“零”水泥制备的碱激发混凝土(AAC)因其具有快硬高强、耐久性好等优异性能,已被认为是一种具有广泛应用潜力的新型绿色胶凝材料。氯盐侵蚀是引起钢筋锈蚀从而导致钢筋混凝土结构耐久性失效的主要原因之一,尤其是在海洋干湿循环区域。因此,开展干湿交替作用下AAC的氯盐侵蚀性能分析对其耐久性理论的发展具有重要意义。将AAC与C50混凝土进行对比,通过自设计的干湿循环全自动实验装置,研究了干湿循环时间比(3.0:1.0、11.0:1.0、85.4:1.0)和暴露时间(30、90、180 d)对AAC氯盐侵蚀性能的影响;基于此,建立了干湿循环作用下氯盐侵蚀理论模型,并进行数值计算与模型验证。结果表明:AAC氯离子含量明显少于C50混凝土,这是由于AAC具有较小的孔隙率和致密的孔隙结构,内部的孔径明显小于C50混凝土,从而表现出更好的抗氯盐侵蚀性能;随着干湿循环时间比的增加,混凝土表面氯离子浓度和表观氯离子扩散系数都呈现先增大后减小趋势;经验证,利用所建立的干湿循环作用下非饱和混凝土氯离子传输模型的数值计算结果与试验结果吻合较好。Alkali-activated concrete(AAC)prepared without cement with the performance of rapid hardening,high strength and good durability,is recognized as one of novel green building materials with a wide application potential.Chloride ingress into concrete to cause the process of steel corrosion is one of the main reasons to the durability failure of reinforced concrete structures,particularly exposed to marine cyclic drying-wetting zones.It is thus of great significance for the development of durability theory to conduct the chloride ingress resistance analysis of AAC under drying-wetting cycles.Compared with concrete C50,the effects of cyclic drying-wetting time ratio(i.e.3.0:1.0,11.0:1.0 and 85.4:1.0)and exposure time(i.e.30,90 and 180 d)on the chloride ingress properties of AAC were investigated via a designed automatic experimental set-up of cyclic drying-wetting test.A theoretical model of chloride ingress into AAC under drying-wetting cycles was proposed for numerical calculation.The results show that the chloride content within AAC is obviously less than that in concrete C50.This is because AAC has a smaller porosity and a denser pore microstructure rather than concrete C50,thus exhibiting a better resistance to chloride ingress.The surface chloride concentration and apparent chloride diffusion coefficient of AAC first increase and then decrease as the cyclic drying-wetting time ratio increases.It is indicated that the numerical data of chloride profiles calculated by the proposed model of chloride transport into unsaturated concrete under various conditions of the drying-wetting cycles are in reasonable agreement with the experimental results.

关 键 词：碱激发混凝土 海洋环境 干湿循环 氯盐侵蚀 数值模型 

分 类 号：TU528[建筑科学—建筑技术科学]