干湿循环与风沙吹蚀作用下风积沙混凝土的抗硫酸盐耐久性  

Sulfate Durability of Aeolian Sand Concrete Under Dry-Wet Cycles and Sand Blowing

作　　者：董瑞鑫 申向东[1] 薛慧君[1] 刘倩[1] 维利思 DONG Ruixin;SHEN Xiangdong;XUE Huijun;LIU Qian;WEI Lisi(College of Water Conservancy and Civil Engineering,Inner Mongolia Agricultural University,Hohhot 010018,China)

机构地区：[1]内蒙古农业大学水利与土木建筑工程学院,呼和浩特010018

出　　处：《材料导报》2020年第20期20053-20060,共8页Materials Reports

基　　金：国家自然科学基金(51769025,51569021);内蒙古自然科学基金(2020BS05008)。

摘　　要：选取内蒙古自治区乌兰布和沙漠的风积沙作为细骨料,用掺量为40%的风积沙替代部分河砂,运用扫描电子显微镜和X射线衍射技术观测并分析风积沙混凝土的微观形貌和物相成分,采用核磁共振技术对风积沙混凝土孔隙结构特征进行测试分析,并对其耐久性进行寿命预测。研究表明:风积沙混凝土在耦合工况下的质量损失较单一干湿循环作用下的质量损失增加了2.21倍,耦合工况下的抗压耐蚀系数曲线始终在单一干湿循环作用下的抗压耐蚀系数曲线下方;D120的最大侵蚀深度为1.66 mm,D120S8的沟壑深度为3.51 mm;经过干湿循环120次后,单一干湿作用的水泥浆体出现长度为9μm的细长裂缝,耦合工况中出现长度为18~36μm的贯通裂缝,腐蚀结晶物多为硫酸盐和碳酸盐;两种工况下T 2谱主要呈现两个峰,风积沙混凝土的孔隙在耦合作用下的增长速率大于在单一干湿循环作用下的增长速率;随着干湿循环次数的增加,小孔隙减少,大孔隙增多,其内部的小孔隙向大孔隙转化,孔隙度都与自由流体饱和度的变化规律成正比;通过寿命预测模型求得风积沙混凝土的服役时间为125 a,该研究可为风积沙混凝土在风蚀区硫酸盐环境下的工程建设提供理论依据。Aeolian sands from Ulan Buh Desert in Inner Mongolia Autonomous Region were selected as fine aggregates,40%do sage of aeolian sand was used to replace part of river sand,and scanning electron microscopy and X-ray diffraction techniques were used to observe and analyze the microscopic morphology of aeolian sand concrete.The phase composition was tested by NMR technique on the pore structure characteristics of aeolian sand concrete,and its durability was predicted.The research shows that the mass loss of aeolian sand concrete under coupling conditions is 2.21 times higher than that under a single dry-wet cycle.The curve of compressive and corrosion resistance under coupling conditions is always lower than that of single dry-wet cycle;the maximum erosion depth of D120 is 1.66 mm,the depth of the ditch of D120S8 is 3.51 mm;after 120 cycles of dry and wet cycles,a 9μm slender crack appears in the cement slurry of single dry and wet action,and a through crack of 18—36μm appears in the coupling condition.Most of the corrosion crystallization materials are sulfate and carbonate;the T 2 spectrum mainly shows two peaks under the two conditions.The pore growth rate of aeolian sand concrete under coupling is greater than that of single dry-wet cycle;with the increase of the number of dry-wet cycles,small pores decrease,the large pores increase,transforming the small pores into large pores,and the porosity is proportional to the change of free fluid saturation;the service life of the aeolian sand concrete is 125 a by the life prediction model.This paper provides theoretical basis for the construction of aeolian sand concrete in the sulfate environment of wind erosion area.

关 键 词：风积沙混凝土 干湿循环 风沙吹蚀 微观形貌 物相成分 孔隙特征 寿命预测 

分 类 号：TU528[建筑科学—建筑技术科学]