吉林省西部地区盐渍土环境下混凝土耐久性研究

发布时间：2018-12-21 12:52

【摘要】：混凝土耐久性问题是混凝土材料科学领域的一项重要研究课题。随着混凝土的广泛应用，使用环境的日益恶化，混凝土工程受环境侵蚀的危害性也日益增加，即环境条件的严酷程度决定了混凝土结构工程寿命的长短。在国家自然科学基金项目“东北季冻区路基水份迁移的微观机理研究”（No.406721780）和国家自然科学基金项目“不同气候带几种表生特殊土的形成环境及演化趋势”（No.40911120044）、博士点基金“干湿冻融循环对吉林西部分散土的影响及机理研究”（No.20120061110054）资助下，本文针对吉林西部盐渍土分布区内的混凝土工程为研究对象，，结合吉林西部地区的气候条件与土壤环境等因素，开展了混凝土耐久性的研究工作，主要揭示盐蚀、干湿、冻融等单一或多重因素作用下混凝土性能的衰变规律，进行不同环境因素或土壤情况下混凝土破坏机理分析与评价，以及混凝土耐久性的诸多影响因素与其质量或动弹性模量的关联度分析，以减少季冻区盐碱土对混凝土工程耐久与安全的潜在威胁，并进一步完善混凝土耐久性研究的理论体系。吉林省大安市是松嫩平原土壤盐渍化最严重的地区之一，以苏打盐渍土为主，境内的土壤及地表水中的易溶盐分量相似。针对大安盐渍土区的自然环境特点，模拟实际工程的环境条件设计了四种试验工况，即盐浸、盐蚀-干湿、盐蚀-冻融、盐蚀-冻融-干湿试验；并根据大安春季土壤中主要易溶盐的种类与含量，配制了不同浓度的复合盐侵蚀溶液，根据复合盐中的各种易溶盐分别配置了单盐侵蚀溶液进行对比试验；制备五种不同配合比的基准混凝土、粉煤灰混凝土、引气混凝土试件，进行了以下四组试验：混凝土的复合盐或单盐溶液长期浸泡试验、复合盐或单盐-干湿循环试验、复合盐或单盐-冻融循环试验、复合盐或单盐-冻融-干湿循环试验，以质量与动弹性模量的变化作为混凝土耐久性能的评价指标；同时，通过物理、电镜扫描及超声波等手段进行混凝土在各种试验工况下的性能研究，包括混凝土的破坏规律、破坏机理分析、宏观现象、微观结构、质量损失与动弹性模量衰减规律、以及影响因素等。在以上试验数据的基础上，利用灰关联度法和粗糙集理论对浸泡时间、冻融循环次数、干湿循环次数、冻融-干湿次数、复合盐浓度、含气量、粉煤灰掺量7个影响因素分别与混凝土的质量损失率、相对动弹性模量的关系进行分析，确定各影响因素对混凝土耐久性影响程度的大小，计算权重，并进行不同环境条件下混凝土动弹性模量的衰减规律评价，从而对吉林省西部地区盐渍土环境下混凝土耐久性进行深入研究。
[Abstract]:The durability of concrete is an important research topic in the field of concrete material science. With the extensive application of concrete and the deterioration of the environment, the harm of environmental erosion of concrete engineering is increasing day by day, that is, the severity of environmental conditions determines the length of life of concrete structure engineering. In the project of National Natural Science Foundation of China, "microscopic mechanism of subgrade water migration in northeast seasonal frozen region" (No.406721780) and "formation environment and evolution trend of several kinds of supergene special soil in different climatic zones" (No.40911120044), the project of National Natural Science Foundation of China (NSFC) is presented. The effect and Mechanism of Dry-Wet Freeze-thaw cycle on dispersed soils in Western Jilin Province (No.20120061110054) is supported by the doctoral Program Foundation. This paper focuses on concrete engineering in the saline soil distribution area of western Jilin Province. Combined with the climatic conditions and soil environment in the west of Jilin Province, the durability of concrete is studied, which mainly reveals the decay law of concrete performance under the action of single or multiple factors, such as salt erosion, drying and wet, freezing and thawing, etc. The failure mechanism of concrete is analyzed and evaluated under different environmental factors or soil conditions, and the correlation degree between many factors affecting the durability of concrete and its quality or dynamic modulus of elasticity is analyzed. In order to reduce the potential threat to durability and safety of concrete engineering caused by saline-alkali soil in seasonally frozen area, and further improve the theoretical system of concrete durability research. Da'an City of Jilin Province is one of the most serious soil salinization areas in Songnen Plain. Soda saline soil is the main soil and the soluble salt content in soil and surface water is similar. According to the characteristics of the natural environment in the saline soil area of Da'an, four test conditions were designed to simulate the environmental conditions of the actual engineering, namely, salt leaching, salt erosion-dry-wet, salt-corrosion-freeze-thaw and dry-wet test. According to the types and contents of the main soluble salts in the spring soil of Da'an, different concentrations of complex salt erosion solution were prepared, and the single salt erosion solution was allocated separately according to the various soluble salts in the compound salt. Five kinds of reference concrete, fly ash concrete and air-entrained concrete specimens with different mix ratios were prepared. The following four groups of tests were carried out: the long-term immersion test of the compound salt or single salt solution, the test of the composite salt or the single salt-dry and wet cycle test, Compound salt or single salt-freeze-thaw cycle test, compound salt or single salt-freeze-thawing-dry and wet cycle test, take the change of mass and dynamic elastic modulus as the evaluation index of concrete durability. At the same time, the performance of concrete under various test conditions is studied by means of physics, scanning electron microscope and ultrasonic wave, including the failure law of concrete, the analysis of failure mechanism, the macroscopic phenomenon, the microstructure of concrete, and so on. Mass loss and dynamic elastic modulus attenuation, and influencing factors, etc. On the basis of the above experimental data, the soaking time, freeze-thaw cycle times, dry-wet cycles, freeze-thawing-dry-wet times, complex salt concentration and gas content were analyzed by grey correlation degree method and rough set theory. The relationship between the weight loss rate of concrete and the relative dynamic elastic modulus of concrete is analyzed, and the influence degree of each factor on the durability of concrete is determined and the weight is calculated. The attenuation law of dynamic elastic modulus of concrete under different environmental conditions was evaluated, and the durability of concrete under saline soil environment in western Jilin Province was studied in depth.
【学位授予单位】：吉林大学
【学位级别】：博士
【学位授予年份】：2013
【分类号】：TU528

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