热湿环境下CO_(2)-SO_(2)耦合侵蚀水泥基材料的中性化机理及预测模型  

Neutralization Mechanism and Prediction Model of CO_(2)-SO_(2) Coupled Erosion of Cement-Based Materials in Hot and Wet Environment

作　　者：牛荻涛[1,2] 曹志远 吕瑶[1] NIU Ditao;CAO Zhiyuan;LV Yao(School of Civil Engineering,Xi'an University of Architecture and Technology,Xi'an 710055,China;State Key Laboratory of Green Building in Western China,Xi'an University of Architecture and Technology,Xi'an 710055,China)

机构地区：[1]西安建筑科技大学土木工程学院,西安710055 [2]省部共建绿色建筑国家重点实验室/西安建筑科技大学,西安710055

出　　处：《硅酸盐学报》2024年第2期545-554,共10页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(52078413、51808437);教育部“创新团队发展计划”(IRT_17R84)。

摘　　要：为探究工业环境中水泥基材料耐久性损伤机理,开展了热湿环境CO_(2)-SO_(2)耦合侵蚀下净浆、砂浆和混凝土的中性化试验,并采用核磁共振和电化学阻抗谱等测试方法分析了水泥基材料的孔结构及孔溶液变化,建立了水泥基材料的中性化深度预测模型。结果表明:腐蚀循环前期(0~2次),反应以碳化为主。中期(2~7次),由于CaCO_(3)填充试样的孔隙,使得碳化反应速率减缓。同时SO_(2)与混凝土水化产物发生反应,水化硅酸钙(C-S-H)凝胶脱钙,同时生含结晶水的膨胀产物CaSO_(3)和CaSO_(4),导致有害孔逐渐增加,试样表层产生膨胀裂缝。后期(7~14次),SO_(2)持续腐蚀C-S-H凝胶等水化产物,混凝土孔隙率增大,碳化反应速度加快。Extended Abstract Introduction Although different experiments on the co-corrosion of concrete vulcanization and carbonation are performed,the data are scattered and are not systematic.There are little reports on the mechanism of the performance degradation of cement-based materials due to the coupled effects of high temperature,high humidity,SO_(2) and CO_(2).It is thus of a great theoretical and practical significance to scientifically evaluate the durability of industrial building concrete structures and investigate the durability damage mechanism and performance degradation of industrial building concrete structures.In this paper,the neutralization process of cement-based materials under the coupling action of high temperature,high humidity,SO_(2) and CO_(2) was investigated with the three levels of cement paste,mortar and concrete.The appearance,neutralization depth,and quality change rules of cement-based materials with different water-cement ratios were analyzed.The porosity and pore solution of cement-based materials were determined by nuclear magnetic resonance(NMR)and electrochemical impedance(EIS).In addition,the neutralization mechanism of cement-based materials was discussed,and a prediction model for the neutralization depth of cement-based materials was also established.Methods The cement used was P.O 42.5.The fine aggregate was a natural river sand with a fineness modulus of 2.34,and the coarse aggregate was a granite crushed stone with a continuous gradation of 5-25 mm.Three types of samples were cement paste,mortar,and concrete.In the test,a prism-shaped sample of 100 mm×100 mm×400 mm was used to test the neutralization depth of the sample,and a cubic sample of 100 mm×100 mm×100 mm was used for quality and microscopic tests,with 3 samples in each group.The tests began after 28 d of standard curing of the samples.A concentration ratio of CO_(2) and SO_(2) in the workshop was approximately 20:1,and the temperature and humidity were at 50℃ and 70%,respectively.The rapid carbonation test method

关 键 词：工业环境 水泥基材料 中性化机理 中性化深度 预测模型 

分 类 号：TU528[建筑科学—建筑技术科学]