高抗盐无粗集料超高强混凝土材料的制备研究
发布时间：2018-10-22 06:46
【摘要】：目前,混凝土普遍面临着耐久性不足和抗盐性能差的问题,特别是用于海洋环境的混凝土,由于耐久性不足,造成混凝土使用寿命大大缩短,造成巨大经济损失和资源浪费。因此研究制备出一种高抗盐超高强混凝土,对于海洋工程混凝土的发展和海洋的建设具有重要的意义。本文从各种盐类对混凝土的侵蚀机理和不同矿物掺合料水化反应机理及抗盐性出发,结合超高强混凝土制备的基本原则,选择矿渣微粉、硅灰和粉煤灰作为制备复合胶凝材料的矿物掺合料,采用高性能聚羧酸减水剂粉剂,以一定颗粒粒径的砂子作为细骨料制备高抗盐无粗集料超高强混凝土。本研究首先制备了低熟料比、高矿物掺合料且具有大流动性的复合胶凝材料,其可作为特种胶凝材料直接用于海洋混凝土的制备。然后采用1:1的胶砂比,以水灰比0.23,成型制备抗压强度超过100MPa的超高强无粗集料混凝土,分别采用淡水、人工海水和5%硫酸钠溶液养护混凝土。用XRD和SEM对水化产物的物相和形貌作了研究;以混凝土的干缩率,氯离子渗透系数,海水侵蚀系数和硫酸盐侵蚀系数考察了抗盐性能。研究结果表明:①本试验选用的聚羧酸减水剂粉剂的最适宜用量为0.2%;②试验最佳配合比中复合胶凝材料各部分的比例是水泥45%,矿渣微粉40%,硅灰5%,粉煤灰10%,用配比制备的混凝土28d抗压强度110.3MPa,抗折强度12.1MPa;③采用人工海水和硫酸钠溶液养护的混凝土,28d和56d龄期抗压强度比采用淡水养护的混凝土高;④采用复合胶凝材料制备的混凝土3d抗压强度低于纯水泥制备的混凝土,在7d龄期之后,抗压强度超过后者,显著提高后期强度;⑤复合胶凝材料的加入可以有效提高混凝土的抗压、抗折强度;⑥采用复合胶凝材料制备的混凝土,无论3d还是28d龄期,XRD物相中微斜长石(KAlSi3O8)的衍射峰明显;⑦复合胶凝材料的加入可以有效降低混凝土的干缩率,提高抗氯离子、硫酸盐和海水的侵蚀能力。本研究制备的复合胶凝材料与聚羧酸减水剂粉剂混合后,适用于工业大批量生产,在海岛工程建设中,可作为高抗盐超高强混凝土特种胶凝材料直接使用。本研究制备的高抗盐无粗集料超高强混凝土,具备了超高强和高抗盐的性能,达到了预期的设计目标,对于我国海洋工程岛屿建设具有一定的理论意义和实用价值。
[Abstract]:At present, concrete is generally faced with the problems of poor durability and poor salt resistance, especially for marine environment. Due to the lack of durability, concrete service life is greatly shortened, resulting in huge economic losses and waste of resources. Therefore, it is of great significance for the development and construction of marine engineering concrete to study and prepare a kind of super high strength concrete with high salt resistance. Based on the corrosion mechanism of various salts to concrete, hydration reaction mechanism of different mineral admixtures and salt resistance, combined with the basic principle of preparation of ultra-high strength concrete, the slag powder is selected in this paper. Silica fume and fly ash are used as mineral admixtures for the preparation of composite cementing materials. High salt resistant ultra-high strength concrete without coarse aggregate is prepared by using high performance polycarboxylic acid superplasticizer powder and sand with certain particle size as fine aggregate. In this study, a kind of composite cementing material with low clinker ratio, high mineral admixture and high fluidity was prepared, which can be directly used as a special cementing material in the preparation of marine concrete. Then, the ultra-high strength coarse aggregate concrete with compressive strength exceeding 100MPa was prepared by using the ratio of cement and cement at 1:1 and the ratio of water to cement 0.23. The concrete was cured with fresh water, artificial seawater and 5% sodium sulfate solution, respectively. The phase and morphology of hydration products were studied by XRD and SEM, and the salt resistance was investigated by the dry shrinkage of concrete, the permeability coefficient of chloride ion, the erosion coefficient of seawater and the erosion coefficient of sulfate. The results show that: 1 the optimum dosage of polycarboxylic acid superplasticizer powder used in this experiment is 0.2%. 2 the proportion of each part of compound cementing material in the test is 45% cement, 40 slag powder, 5 silica fume, 10 fly ash, proportion of cement. The 28d compressive strength of the prepared concrete is 110.3MPa, and the flexural strength of the concrete treated with artificial seawater and sodium sulfate solution is 12.1MPa3. The compressive strength of the concrete of 28d and 56d is higher than that of the concrete cured with fresh water. (4) the compressive strength of concrete prepared with composite cementing material is lower than that of concrete prepared with pure cement. After 7 days of age, the compressive strength of concrete is higher than that of the latter, and the later strength is increased significantly. (5) the compressive and flexural strength of concrete can be effectively improved by adding the composite cementing material. (6) the diffraction peak of microplagioclase (KAlSi3O8) in XRD phase is obvious no matter 3 d or 28 d age. The addition of compound cementitious material can effectively reduce the dry shrinkage of concrete and improve the corrosion resistance of chloride, sulfate and seawater. After mixed with polycarboxylic acid superplasticizer powder, the composite cementitious material prepared in this study is suitable for industrial mass production and can be directly used as a special kind of concrete cementitious material with high salt resistance and super high strength in island engineering construction. The ultra-high strength concrete without coarse aggregate prepared in this study has the properties of super high strength and high salt resistance, and achieves the expected design goal, which has certain theoretical significance and practical value for the construction of marine engineering islands in China.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528
本文编号：2286400
[Abstract]:At present, concrete is generally faced with the problems of poor durability and poor salt resistance, especially for marine environment. Due to the lack of durability, concrete service life is greatly shortened, resulting in huge economic losses and waste of resources. Therefore, it is of great significance for the development and construction of marine engineering concrete to study and prepare a kind of super high strength concrete with high salt resistance. Based on the corrosion mechanism of various salts to concrete, hydration reaction mechanism of different mineral admixtures and salt resistance, combined with the basic principle of preparation of ultra-high strength concrete, the slag powder is selected in this paper. Silica fume and fly ash are used as mineral admixtures for the preparation of composite cementing materials. High salt resistant ultra-high strength concrete without coarse aggregate is prepared by using high performance polycarboxylic acid superplasticizer powder and sand with certain particle size as fine aggregate. In this study, a kind of composite cementing material with low clinker ratio, high mineral admixture and high fluidity was prepared, which can be directly used as a special cementing material in the preparation of marine concrete. Then, the ultra-high strength coarse aggregate concrete with compressive strength exceeding 100MPa was prepared by using the ratio of cement and cement at 1:1 and the ratio of water to cement 0.23. The concrete was cured with fresh water, artificial seawater and 5% sodium sulfate solution, respectively. The phase and morphology of hydration products were studied by XRD and SEM, and the salt resistance was investigated by the dry shrinkage of concrete, the permeability coefficient of chloride ion, the erosion coefficient of seawater and the erosion coefficient of sulfate. The results show that: 1 the optimum dosage of polycarboxylic acid superplasticizer powder used in this experiment is 0.2%. 2 the proportion of each part of compound cementing material in the test is 45% cement, 40 slag powder, 5 silica fume, 10 fly ash, proportion of cement. The 28d compressive strength of the prepared concrete is 110.3MPa, and the flexural strength of the concrete treated with artificial seawater and sodium sulfate solution is 12.1MPa3. The compressive strength of the concrete of 28d and 56d is higher than that of the concrete cured with fresh water. (4) the compressive strength of concrete prepared with composite cementing material is lower than that of concrete prepared with pure cement. After 7 days of age, the compressive strength of concrete is higher than that of the latter, and the later strength is increased significantly. (5) the compressive and flexural strength of concrete can be effectively improved by adding the composite cementing material. (6) the diffraction peak of microplagioclase (KAlSi3O8) in XRD phase is obvious no matter 3 d or 28 d age. The addition of compound cementitious material can effectively reduce the dry shrinkage of concrete and improve the corrosion resistance of chloride, sulfate and seawater. After mixed with polycarboxylic acid superplasticizer powder, the composite cementitious material prepared in this study is suitable for industrial mass production and can be directly used as a special kind of concrete cementitious material with high salt resistance and super high strength in island engineering construction. The ultra-high strength concrete without coarse aggregate prepared in this study has the properties of super high strength and high salt resistance, and achieves the expected design goal, which has certain theoretical significance and practical value for the construction of marine engineering islands in China.
【学位授予单位】：武汉理工大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528
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