氯鹽侵蝕混凝土過程的精細化數(shù)值模擬與試驗研究
發(fā)布時間：2019-04-29 08:56
【摘要】：氯鹽侵蝕混凝土結(jié)構(gòu)是混凝土耐久性研究的一個重點和難點。由于近些年自密實混凝土在公路和橋梁中的應用越來越廣泛,其耐久性能的研究并不充足,因此自密實混凝土耐久性的研究顯得更為迫切和重要。隨著混凝土材料向高性能方向的發(fā)展,以節(jié)約能源和節(jié)省原材料、采用活性礦物摻合料與高效減水劑來配制高性能、高耐久性的混凝土已成為全世界的建筑課題,粉煤灰、礦粉和硅粉等活性礦物常被作為摻合料而成為混凝土的組成成分。由于氯鹽侵蝕混凝土的機理尚不完善,國內(nèi)外關(guān)于氯鹽侵蝕混凝土的耐久性的研究大多以試驗為主,關(guān)于氯離子侵蝕自密實混凝土的耐久性能的研究更少,對于摻和了礦物摻合料的自密實混凝土的研究更是寥寥無幾。在調(diào)研已有的研究成果的基礎(chǔ)上,本文主要對以下內(nèi)容進行了研究:首先,進行了氯鹽溶液浸泡侵蝕自密實混凝土的試驗和氯鹽鹽霧侵蝕自密實混凝土的試驗,試驗過程中把水膠比、摻合料種類、摻合量和氯鹽組成成分作為控制變量。試驗選用三種不同的礦物摻合料(粉煤灰、礦粉和硅粉)進行研究,試驗中摻和了礦物摻合料的自密實混凝土試件共有九種不同的配比。每種配比的自密實混凝土試件選用一種摻合料,對于選用了同一種摻合料的自密實混凝土試件選用兩種不同的摻合量,保證不同配比的自密實混凝土試件的摻合料類型和摻合量是不同的,同時,試驗過程中選用不摻礦物摻合料的自密實混凝土試件作為對照組。試驗過程中每隔30天從試驗裝置中取出自密實混凝土試件,測定混凝土試件內(nèi)部不同深度處的自由氯離子濃度和總氯離子濃度以及立方體抗壓強度,進而對氯鹽侵蝕自密實混凝土的耐久性能進行研究。其次使用RCM法對自密實混凝土的氯離子擴散系數(shù)進行試驗研究,試驗選用NaCl溶液對自密實混凝土試件進行氯鹽溶液浸泡試驗。從自密實混凝土圓柱體試件浸泡到氯鹽溶液中開始,每隔30天測量一次自密實混凝土試件的氯離子擴散系數(shù),通過Matlab對不同浸泡齡期的自密實混凝土的氯離子擴散系數(shù)進行擬合分析,得到了九種不同配比的自密實混凝土的氯離子擴散系數(shù)隨時間變化的曲線,根據(jù)擬合結(jié)果對不同齡期的自密實混凝土的氯離子擴散系數(shù)進行預測。最后,在Fick第二定律的基礎(chǔ)上,在偏微分方程組中引入反應項,建立了更為合理的考慮氯離子擴散反應和吸附-釋放動態(tài)平衡反應耦合作用的偏微分方程組。利用三級配骨料理論和孔隙概率密度函數(shù),使用Matlab軟件編寫了混凝土骨料投放的程序,同時基于Abaqus商業(yè)軟件的二次開發(fā),通過編寫Matlab程序在一定程度上實現(xiàn)了氯鹽侵蝕自密實混凝土的多尺度精細化數(shù)值化模型的建立和計算。通過模型計算結(jié)果和試驗實測數(shù)據(jù)的對比,驗證了本研究中新建偏微分方程組、的合理性和準確性。
[Abstract]:Chloride erosion of concrete structure is a key and difficult point in the study of concrete durability. Since the application of self-compacting concrete in highway and bridge is more and more extensive in recent years, the research on durability of self-compacting concrete is not enough, so the research on durability of self-compacting concrete is more urgent and important. With the development of concrete materials in the direction of high performance, in order to save energy and raw materials, using active mineral admixture and superplasticizer to prepare high performance, high durability concrete has become the construction subject of the world, fly ash, Active minerals, such as mineral powder and silica powder, are often used as admixtures and become the components of concrete. Because the mechanism of chloride erosion concrete is not perfect, the durability of chloride erosion concrete is mostly studied by experiment at home and abroad, and the research on durability of chloride-ion erosion self-compacting concrete is less than that of chloride-ion erosion self-compacting concrete. The study of self-compacting concrete mixed with mineral admixture is rare. Based on the existing research results, the main contents of this paper are as follows: firstly, the test of chloride solution immersion erosion self-compacting concrete and the test of chloride salt spray erosion self-compacting concrete are carried out. During the experiment, the ratio of water to binder, the type of admixture, the amount of admixture and the composition of chlorine salt were used as the controlling variables. Three kinds of mineral admixtures (fly ash, mineral powder and silica powder) were used in the experiment. There were nine different ratios of self-compacting concrete specimens mixed with mineral admixtures. One admixture is selected for each self-compacting concrete specimen, and two different admixtures are selected for the self-compacting concrete specimen with the same admixture. The type and amount of admixture of self-compacting concrete specimens with different proportions are different. Meanwhile, the self-compacting concrete specimens without mineral admixture are selected as the control group during the test. During the test, self-compacting concrete specimens were taken out every 30 days, and the free chloride concentration, total chloride concentration and cube compressive strength were measured at different depths within the concrete specimen. Furthermore, the durability of self-compacting concrete corroded by chloride salt was studied. Secondly, the chloride diffusion coefficient of self-compacting concrete was studied by RCM method. The NaCl solution was used to soak the self-compacting concrete specimen in chloride solution. The chloride diffusion coefficient of self-compacting concrete specimen is measured every 30 days, starting from immersion of self-compacting concrete cylinder specimen into chloride solution. According to the fitting analysis of chloride diffusion coefficient of self-compacting concrete with different immersion age by Matlab, the curve of chloride diffusion coefficient of nine kinds of self-compacting concrete with different proportion with time has been obtained, which shows that the diffusion coefficient of chloride ion in self-compacting concrete varies with time. According to the fitting results, the chloride diffusion coefficient of self-compacting concrete of different ages is predicted. Finally, on the basis of Fick's second law, the reaction term is introduced into the partial differential equations, and a more reasonable partial differential equation system considering the coupling action of chloride diffusion reaction and adsorption-release dynamic equilibrium reaction is established. Based on the three-grade aggregate theory and the pore probability density function, the program of concrete aggregate delivery is compiled by using Matlab software. At the same time, the secondary development of commercial software based on Abaqus is carried out. The multi-scale refined numerical model of self-compacting concrete corroded by chlorine salt is established and calculated by programming Matlab program to a certain extent. The rationality and accuracy of the new partial differential equations in this study are verified by the comparison between the calculated results of the model and the measured data.
【學位授予單位】：東南大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU528
本文編號：2468135
[Abstract]:Chloride erosion of concrete structure is a key and difficult point in the study of concrete durability. Since the application of self-compacting concrete in highway and bridge is more and more extensive in recent years, the research on durability of self-compacting concrete is not enough, so the research on durability of self-compacting concrete is more urgent and important. With the development of concrete materials in the direction of high performance, in order to save energy and raw materials, using active mineral admixture and superplasticizer to prepare high performance, high durability concrete has become the construction subject of the world, fly ash, Active minerals, such as mineral powder and silica powder, are often used as admixtures and become the components of concrete. Because the mechanism of chloride erosion concrete is not perfect, the durability of chloride erosion concrete is mostly studied by experiment at home and abroad, and the research on durability of chloride-ion erosion self-compacting concrete is less than that of chloride-ion erosion self-compacting concrete. The study of self-compacting concrete mixed with mineral admixture is rare. Based on the existing research results, the main contents of this paper are as follows: firstly, the test of chloride solution immersion erosion self-compacting concrete and the test of chloride salt spray erosion self-compacting concrete are carried out. During the experiment, the ratio of water to binder, the type of admixture, the amount of admixture and the composition of chlorine salt were used as the controlling variables. Three kinds of mineral admixtures (fly ash, mineral powder and silica powder) were used in the experiment. There were nine different ratios of self-compacting concrete specimens mixed with mineral admixtures. One admixture is selected for each self-compacting concrete specimen, and two different admixtures are selected for the self-compacting concrete specimen with the same admixture. The type and amount of admixture of self-compacting concrete specimens with different proportions are different. Meanwhile, the self-compacting concrete specimens without mineral admixture are selected as the control group during the test. During the test, self-compacting concrete specimens were taken out every 30 days, and the free chloride concentration, total chloride concentration and cube compressive strength were measured at different depths within the concrete specimen. Furthermore, the durability of self-compacting concrete corroded by chloride salt was studied. Secondly, the chloride diffusion coefficient of self-compacting concrete was studied by RCM method. The NaCl solution was used to soak the self-compacting concrete specimen in chloride solution. The chloride diffusion coefficient of self-compacting concrete specimen is measured every 30 days, starting from immersion of self-compacting concrete cylinder specimen into chloride solution. According to the fitting analysis of chloride diffusion coefficient of self-compacting concrete with different immersion age by Matlab, the curve of chloride diffusion coefficient of nine kinds of self-compacting concrete with different proportion with time has been obtained, which shows that the diffusion coefficient of chloride ion in self-compacting concrete varies with time. According to the fitting results, the chloride diffusion coefficient of self-compacting concrete of different ages is predicted. Finally, on the basis of Fick's second law, the reaction term is introduced into the partial differential equations, and a more reasonable partial differential equation system considering the coupling action of chloride diffusion reaction and adsorption-release dynamic equilibrium reaction is established. Based on the three-grade aggregate theory and the pore probability density function, the program of concrete aggregate delivery is compiled by using Matlab software. At the same time, the secondary development of commercial software based on Abaqus is carried out. The multi-scale refined numerical model of self-compacting concrete corroded by chlorine salt is established and calculated by programming Matlab program to a certain extent. The rationality and accuracy of the new partial differential equations in this study are verified by the comparison between the calculated results of the model and the measured data.
【學位授予單位】：東南大學
【學位級別】：碩士
【學位授予年份】：2017
【分類號】：TU528
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，本文編號：2468135
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