本文選題：再生混凝土　切入點：氯離子　出處：《廣西大學》2017年碩士論文

【摘要】：再生混凝土作為一種可持續(xù)發(fā)展的綠色建筑材料,實現(xiàn)了資源的循環(huán)利用,符合國家可持續(xù)發(fā)展戰(zhàn)略的需求。由于再生粗骨料表面附著舊砂漿,所以再生混凝土存在舊砂漿—原生粗骨料和新砂漿—舊砂漿雙界面過渡區(qū),從而影響到再生混凝土的耐久性。本文把再生混凝土視為由新砂漿、附著舊砂漿、原生粗骨料、新砂漿—附著舊砂漿之間的新界面過渡區(qū)、附著舊砂漿—原生粗骨料之間的舊界面過渡區(qū)組成的五相復合材料,從有限元數(shù)值模型和等效擴散系數(shù)計算模型兩方面對再生混凝土中的氯離子擴散規(guī)律進行分析,并通過自然擴散試驗對數(shù)值模型和計算模型進行了驗證。本文的主要研究工作和結論包括:(1)建立了考慮粗骨料隨機分布的再生混凝土中氯離子擴散的五相數(shù)值模型�；谠偕止橇想S機投放的雙向游走法,研究建立圓形粗骨料隨機投放下的再生混凝土五相模型和再生混凝土三相+五相復合模型,并討論了模型中各參數(shù)的合理取值,分析表明,建立再生混凝土五相模型能夠考慮附著舊砂漿和雙界面過渡區(qū)的影響,能夠更為合理地評估氯離子在再生混凝土中的擴散行為;(2)利用粗骨料級配分布理論提出了再生混凝土中雙界面過渡區(qū)的面積分數(shù)計算模型,結合雙界面過渡區(qū)的氯離子擴散系數(shù),基于Viogt-Reuss模型分析再生混凝土擴散系數(shù)的上下限,在此基礎上研究建立了定量計算再生混凝土等效擴散系數(shù)的計算模型,分析表明,所提出的再生混凝土中雙界面過渡區(qū)的面積分數(shù)計算模型精度較高,當粗骨料在模型中分布較為均勻時,等效擴散系數(shù)計算模型的結果與數(shù)值模擬結果吻合較好;(3)以粗骨料含量、水膠比、再生粗骨料取代率、粉煤灰摻量、礦粉摻量、粗骨料級配作為考察因素,設計了 8組再生混凝土的配合比并進行制備,進而開展了再生混凝土中氯離子自然擴散試驗,試驗結果表明,降低再生粗骨料取代率能夠提高再生混凝土的抗氯鹽侵蝕性能,粗骨料含量為45%的再生混凝土抗氯鹽侵蝕性能較好,控制粗骨料粒徑在10～15mm、降低水膠比均能較好地提高再生混凝土的抗氯鹽侵蝕性能,單摻粉煤灰的再生混凝土的耐久性低于復摻粉煤灰和礦粉的再生混凝土和單摻礦粉的再生混凝土;(4)基于自然擴散試驗所測定的再生混凝土試塊中氯離子濃度與擴散深度的關系,將試驗數(shù)據(jù)分別與再生混凝土中氯離子擴散的五相數(shù)值模型的分析結果和再生混凝土等效擴散系數(shù)計算模型的分析結果進行對比分析,驗證了再生混凝土中氯離子擴散的五相數(shù)值模型和再生混凝土等效擴散系數(shù)計算模型的合理性和適用性。
[Abstract]:As a green building material for sustainable development, recycled concrete realizes the recycling of resources and meets the needs of the national sustainable development strategy. Therefore, there is a transition zone between old mortar and primary coarse aggregate and new mortar and old mortar in recycled concrete, which affects the durability of recycled concrete. In this paper, recycled concrete is regarded as new mortar, attached old mortar, primary coarse aggregate. A five-phase composite consisting of a new interfacial transition zone between new mortar and attached old mortar, and a five-phase composite composed of an old interface transition zone between old mortar and primary coarse aggregate, The diffusion law of chloride ions in recycled concrete is analyzed from two aspects: finite element numerical model and equivalent diffusion coefficient calculation model. The numerical model and computational model are verified by natural diffusion test. The main research work and conclusions in this paper include: 1) the five-phase numerical model of chloride diffusion in recycled concrete considering the random distribution of coarse aggregate is established. Bidirectional walking method based on random drop of recycled coarse aggregate, The five-phase model of recycled concrete and three-phase five-phase composite model of recycled concrete under random dropping of circular coarse aggregate are studied and the reasonable values of each parameter in the model are discussed. The five-phase model of recycled concrete can take into account the influence of the adhesion of the old mortar and the transition zone between the two interfaces. The diffusion behavior of chloride ions in recycled concrete can be evaluated more reasonably. Based on the theory of coarse aggregate gradation distribution, a model for calculating the area fraction of double interface transition zone in recycled concrete is proposed. Combined with the chloride ion diffusion coefficient in the transition zone between the two interfaces, the upper and lower limits of the reclaimed concrete diffusion coefficient are analyzed based on Viogt-Reuss model. Based on the above analysis, a quantitative calculation model for the equivalent diffusion coefficient of recycled concrete is established, and the results show that the equivalent diffusion coefficient of recycled concrete is calculated quantitatively. The proposed model for calculating the area fraction of the double interface transition zone in recycled concrete has a high accuracy, and when coarse aggregate is distributed uniformly in the model, The results of the equivalent diffusion coefficient model are in good agreement with the numerical simulation results. The main factors are the content of coarse aggregate, the ratio of water to binder, the replacement rate of regenerated coarse aggregate, the content of fly ash, the amount of mineral powder and the gradation of coarse aggregate. Eight groups of recycled concrete were designed and prepared, and the natural diffusion test of chloride ions in recycled concrete was carried out. The results showed that reducing the replacement rate of recycled coarse aggregate could improve the corrosion resistance of recycled concrete. The recycled concrete with 45% coarse aggregate has better resistance to chloride erosion. Controlling coarse aggregate particle size at 1015 mm and reducing the water-binder ratio can improve the chloride corrosion resistance of recycled concrete. The durability of recycled concrete with single fly ash is lower than that of recycled concrete mixed with fly ash and mineral powder and recycled concrete with single mineral powder. Based on the relationship between chloride concentration and diffusion depth in recycled concrete samples measured by natural diffusion test, The experimental data are compared with the analytical results of the five-phase numerical model of chloride diffusion in recycled concrete and the analytical results of the equivalent diffusion coefficient of recycled concrete. The validity and applicability of the five-phase numerical model of chloride diffusion in recycled concrete and the calculation model of equivalent diffusion coefficient of recycled concrete are verified.
【學位授予單位】：廣西大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU528

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