【摘要】：目前,混凝土普遍面臨著耐久性不足和抗鹽性能差的問(wèn)題,特別是用于海洋環(huán)境的混凝土,由于耐久性不足,造成混凝土使用壽命大大縮短,造成巨大經(jīng)濟(jì)損失和資源浪費(fèi)。因此研究制備出一種高抗鹽超高強(qiáng)混凝土,對(duì)于海洋工程混凝土的發(fā)展和海洋的建設(shè)具有重要的意義。本文從各種鹽類對(duì)混凝土的侵蝕機(jī)理和不同礦物摻合料水化反應(yīng)機(jī)理及抗鹽性出發(fā),結(jié)合超高強(qiáng)混凝土制備的基本原則,選擇礦渣微粉、硅灰和粉煤灰作為制備復(fù)合膠凝材料的礦物摻合料,采用高性能聚羧酸減水劑粉劑,以一定顆粒粒徑的砂子作為細(xì)骨料制備高抗鹽無(wú)粗集料超高強(qiáng)混凝土。本研究首先制備了低熟料比、高礦物摻合料且具有大流動(dòng)性的復(fù)合膠凝材料,其可作為特種膠凝材料直接用于海洋混凝土的制備。然后采用1:1的膠砂比,以水灰比0.23,成型制備抗壓強(qiáng)度超過(guò)100MPa的超高強(qiáng)無(wú)粗集料混凝土,分別采用淡水、人工海水和5%硫酸鈉溶液養(yǎng)護(hù)混凝土。用XRD和SEM對(duì)水化產(chǎn)物的物相和形貌作了研究;以混凝土的干縮率,氯離子滲透系數(shù),海水侵蝕系數(shù)和硫酸鹽侵蝕系數(shù)考察了抗鹽性能。研究結(jié)果表明:①本試驗(yàn)選用的聚羧酸減水劑粉劑的最適宜用量為0.2%;②試驗(yàn)最佳配合比中復(fù)合膠凝材料各部分的比例是水泥45%,礦渣微粉40%,硅灰5%,粉煤灰10%,用配比制備的混凝土28d抗壓強(qiáng)度110.3MPa,抗折強(qiáng)度12.1MPa;③采用人工海水和硫酸鈉溶液養(yǎng)護(hù)的混凝土,28d和56d齡期抗壓強(qiáng)度比采用淡水養(yǎng)護(hù)的混凝土高;④采用復(fù)合膠凝材料制備的混凝土3d抗壓強(qiáng)度低于純水泥制備的混凝土,在7d齡期之后,抗壓強(qiáng)度超過(guò)后者,顯著提高后期強(qiáng)度;⑤復(fù)合膠凝材料的加入可以有效提高混凝土的抗壓、抗折強(qiáng)度;⑥采用復(fù)合膠凝材料制備的混凝土,無(wú)論3d還是28d齡期,XRD物相中微斜長(zhǎng)石(KAlSi3O8)的衍射峰明顯;⑦復(fù)合膠凝材料的加入可以有效降低混凝土的干縮率,提高抗氯離子、硫酸鹽和海水的侵蝕能力。本研究制備的復(fù)合膠凝材料與聚羧酸減水劑粉劑混合后,適用于工業(yè)大批量生產(chǎn),在海島工程建設(shè)中,可作為高抗鹽超高強(qiáng)混凝土特種膠凝材料直接使用。本研究制備的高抗鹽無(wú)粗集料超高強(qiáng)混凝土,具備了超高強(qiáng)和高抗鹽的性能,達(dá)到了預(yù)期的設(shè)計(jì)目標(biāo),對(duì)于我國(guó)海洋工程島嶼建設(shè)具有一定的理論意義和實(shí)用價(jià)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.
【學(xué)位授予單位】：武漢理工大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類號(hào)】：TU528

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