引用本文:胡欢欢,左晓宝,李向南,何绍丽,汤玉娟.低速水流作用下水泥砂浆溶蚀特性研究[J].水利水运工程学报,2019,(1):50-59
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低速水流作用下水泥砂浆溶蚀特性研究
胡欢欢, 左晓宝, 李向南, 何绍丽, 汤玉娟
南京理工大学理学院土木工程系,江苏南京
摘要:
为在较短时间内获得低速水流作用下流速对水泥砂浆等水泥基材料溶蚀特性的影响规律,采用1 mol/L NH4Cl溶液作为流水腐蚀介质,开展了室温(25 ℃)环境下水灰比为0.45的水泥砂浆圆柱体试件在0,0.5, 1.0和2.5 m/s流速下的加速溶蚀试验,并通过酚酞滴定、干燥称重法、扫描电子显微镜(SEM/EDS)、X射线衍射法(XRD)等测试方法,分析了腐蚀前和腐蚀15,30和60 d时水泥砂浆试件的溶蚀深度、孔隙率、物相组成和微结构的演变规律。结果表明,试件的溶蚀深度和孔隙率均随腐蚀时间和流速的增加而增加;浸泡(0 m/s)条件下,试件的溶蚀深度与腐蚀时间平方根呈线性关系,且随着流速的增加,溶蚀深度与腐蚀时间平方根关系趋于非线性;水泥砂浆溶蚀区粉末样品的CSH凝胶等物相衍射峰强度随流速的增加而降低;随流速的增加,水泥砂浆内氢氧化钙、CSH凝胶等溶蚀加快,其微结构劣化程度加剧。
关键词:  水泥砂浆  溶蚀  流速  NH4Cl溶液  溶蚀深度  微结构
DOI:
分类号:TU528
基金项目:国家自然科学基金资助项目(51778297)
Study on leaching characteristics of cement mortar under flowing water with low velocity
HU Huanhuan, ZUO Xiaobao, LI Xiangnan, HE Shaoli, TANG Yujuan
Department of Civil Engineering, School of Science, Nanjing University of Science & Technology, Nanjing
Abstract:
In order to analyze the influence of the low flow velocity of water on the leaching characteristics of cement-based materials like cement mortar in a short time, 1 mol/L NH4Cl solution with the flow velocity of 0, 0.5,1.0 and 2.5 m/s was used as corrosion solutions to carry out accelerated leaching experiments on the cement mortar cylinder specimens with the water-cement ratio of 0.45 at room temperature (25 ℃). By using some measurements, such as the phenolphthalein indicator, saturation-drying weighing, X ray diffraction (XRD) and scanning electron microscopy with energy dispersive spectrometer (SEM/EDS), the leaching depth, porosity, phase composition and microstructure morphology of specimens before and after leaching for 15, 30 and 60 days were analyzed. Results show that the leaching depth and porosity of specimens increase with the leaching time and flow velocity. During the immersion (the flow velocity is zero), the leaching depth of specimens is linear with the square root of the leaching time. With the increase of flow velocity, there appear gradually a non-linear relationship between the leaching depth of specimen and the square root of leaching time, and a decrease in the relative intensity of the diffraction peaks of the CSH phase in the powder sample from the leaching zone of specimen, and an accelerated the dissolution of calcium hydroxide and CSH gel in cement mortar, which indicates that the flow velocity can accelerate the microstructure deterioration of cement mortar in the flowing solution.
Key words:  cement mortar  leaching  flow velocity  NH4Cl solution  leaching depth  microstructure
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