本文選題：干濕交替　切入點：混凝土耐久性　出處：《西安建筑科技大學(xué)》2013年博士論文　論文類型：學(xué)位論文

【摘要】：氯離子侵蝕引起的鋼筋銹蝕，是導(dǎo)致海洋環(huán)境下混凝土結(jié)構(gòu)耐久性破壞的主要原因。浪濺區(qū)、潮汐區(qū)的混凝土因遭受干濕交替作用下的氯離子侵蝕，耐久性劣化情況更為嚴重。首先，針對干濕交替環(huán)境下混凝土結(jié)構(gòu)的氯離子侵蝕，對氯離子在混凝土結(jié)構(gòu)中的傳輸機理進行了系統(tǒng)分析，構(gòu)建了氯離子的對流—擴散傳輸模型，并通過干濕交替循環(huán)試驗進行驗證。然后，利用線性極化法進行了鋼筋銹蝕狀態(tài)的檢測，測定了干濕交替環(huán)境下混凝土結(jié)構(gòu)臨界氯離子濃度值。接下來，考慮收縮和荷載作用，深入探討了損傷混凝土中的氯離子傳輸規(guī)律，建議使用硅烷或工程用水泥基復(fù)合材料（ECC）作為混凝土結(jié)構(gòu)表層防護材料。最后，基于可靠度理論提出了滿足目標(biāo)可靠指標(biāo)的耐久性概率設(shè)計方法，為干濕交替環(huán)境下混凝土結(jié)構(gòu)耐久性設(shè)計提供參考依據(jù)。主要研究內(nèi)容和成果如下： （1）干濕交替環(huán)境下混凝土的氯離子傳輸機理 氯離子主要通過毛細吸收和擴散等方式對混凝土造成侵蝕。首先，根據(jù)干濕交替環(huán)境下混凝土的工程實際情況，建立了氯離子的對流—擴散傳輸模型，并且采用有限差分格式進行了方程求解，進行了氯離子干濕交替侵蝕混凝土的試驗。試驗中所測定的氯離子含量分布與數(shù)值模擬的結(jié)果吻合。這表明，對流—擴散傳輸模型較好反映出了干濕交替環(huán)境下混凝土結(jié)構(gòu)的氯離子傳輸規(guī)律。數(shù)值模擬和試驗結(jié)果都說明干燥—潤濕時間比是氯離子峰值和滲透深度的關(guān)鍵影響因素，隨著干燥—潤濕時間比例增加，氯離子峰值呈現(xiàn)出增大的趨勢，滲透深度也在變大。 （2）干濕交替環(huán)境下的臨界氯離子濃度 氯離子臨界濃度是影響海洋環(huán)境下混凝土結(jié)構(gòu)服役壽命的一個關(guān)鍵參數(shù)。制備了四種不同水膠比的混凝土試件，使用5%的NaCl溶液，在60%的相對濕度下，進行了干濕循環(huán)試驗。試驗中，依據(jù)鋼筋腐蝕電流密度對銹蝕狀況進行定時檢測，測定了銹蝕發(fā)生時混凝土不同深度處的氯離子含量。最后，確定了具有90%保證率的干濕交替環(huán)境下不同混凝土的臨界氯離子濃度值。考慮碳化程度進行氯離子含量的測定和臨界氯離子濃度值的統(tǒng)計分析，使得試驗更接近工程實際，提高了試驗結(jié)果的科學(xué)性和適用性，也為進一步進行干濕交替環(huán)境下混凝土結(jié)構(gòu)的試驗研究提供了參考。 （3）表層防護后混凝土中的氯離子傳輸 由混凝土的外部荷載、早期收縮而產(chǎn)生的裂縫，為氯離子的滲入提供了便利通道，，加速了鋼筋銹蝕，降低了混凝土結(jié)構(gòu)的耐久性能。通過混凝土加載和約束收縮條件下的氯離子侵蝕試驗，研究了損傷混凝土中的氯離子傳輸規(guī)律。混凝土中氯離子擴散系數(shù)隨拉應(yīng)力的增加而增加，70%應(yīng)力水平后急劇增大；氯離子侵蝕量隨混凝土裂縫寬度增加而增加；在同樣加載和約束收縮條件下，經(jīng)硅烷或ECC表面防護的混凝土比普通混凝土具有更好的抗侵蝕性能。 （4）表層防護后混凝土的耐久性設(shè)計 依據(jù)氯離子對流—擴散傳輸模型的數(shù)值模擬與試驗測得的臨界氯離子濃度值，基于可靠度理論，考慮荷載和早期收縮產(chǎn)生的損傷因素，提供了具體的概率計算方法，以解決干濕交替環(huán)境下混凝土表層防護的耐久性設(shè)計問題。對于采用硅烷或ECC作為表面防護材料的混凝土結(jié)構(gòu)，以氯離子擴散系數(shù)和保護層厚度作為主要設(shè)計參數(shù)，對混凝土結(jié)構(gòu)進行了表層防護的耐久性設(shè)計，以滿足設(shè)計使用年限內(nèi)的目標(biāo)可靠指標(biāo)。
[Abstract]:Reinforcement corrosion caused by chloride ion erosion is the main cause of failure of the durability of concrete structure in marine environment. The splash zone, tidal zone of concrete due to alternate chloride ion erosion and deterioration of durability situation is more serious. Firstly, according to the concrete structure under the Chloride Erosion of the wet dry. The transmission mechanism of chloride ion in concrete structure are analyzed systematically, constructs the convection diffusion model of chloride transport and verified by cyclic alternating wet and dry test. Then, the detection of steel corrosion condition using linear polarization method, the critical concentration of chloride ion in concrete structure under dry wet alternation was determined. The next value consider, shrinkage and load, discusses the chloride ion transport law of damage in concrete, recommend the use of silane or engineering cementitious composites (ECC) as Finally, based on the theory of reliability, a probabilistic design method for durability of concrete structures is proposed, which provides a reference for durability design of concrete structures under dry and wet alternative environment. The main contents and achievements are as follows:
(1) the mechanism of chloride transport in concrete under dry and wet environment
The chloride ion mainly through capillary absorption and diffusion of concrete caused by erosion. First of all, according to the actual condition of concrete under the environment of alternating wet and dry, a convection - diffusion model of chloride transport and the use of the finite difference scheme of the equation, for the chloride ion erosion of concrete. The alternate test was in simulation experiments of distribution of chloride ion content and numerical results are in good agreement. This indicates that the convection diffusion transfer model better reflects the environment of concrete chloride ion transport law. Alternate numerical simulation and experimental results show that the drying - wetting time ratio are the key factors that affect the peak value and penetration depth of chloride, with dry - wetting time was increased, the chloride peak increases, the penetration depth is also larger.
(2) the critical chloride concentration in the alternating dry and wet environment
Critical concentration of chloride ions is a key parameter affecting the service life of concrete structures in marine environment. The preparation of four kinds of concrete with different water binder ratio of the specimen, using 5% NaCl solution, the relative humidity of 60%, the dry wet cycling test. In the test, on the basis of corrosion current density on the timing detection the corrosion of chloride ion content at different depth of concrete corrosion occurs is determined. Finally, determine the rate of 90% that the alternate critical chloride concentration of concrete under different environmental value. Considering the degree of carbonation were used for statistical analysis of chloride ion content determination and critical chloride concentration, which is more close to the engineering test actually, improves the scientificity and applicability of the test results, but also for the further study of the concrete structure of alternating wet and dry environment to provide a reference.
(3) chloride transport in concrete after surface protection
By the external load of concrete cracks, early shrinkage, provides a convenient channel for chloride ion penetration, accelerate the steel corrosion, reduce the durability of concrete structures. By chloride ion loading and restrained shrinkage of concrete under erosion test, studied the chloride ion transport law of damage in the concrete. The concrete increase the chloride ion diffusion coefficient with tensile stress increased, stress level increases sharply after 70%; chloride ion erosion of concrete crack width increases; under the same loading conditions and restrained shrinkage, the protective silane or ECC concrete has better corrosion resistance.
(4) durability design of concrete after surface protection
Based on the critical chloride concentration of experiment and numerical simulation of chloride ion diffusion convection transport model of measured values, based on the theory of reliability, considering damage factors and early shrinkage load, calculation method provides specific probability, to solve the problem of durability design of concrete surface protection of the environment. For the use of silane or alternate ECC as the concrete surface protection materials, the chloride ion diffusion coefficient and the thickness of the protective layer as the main design parameter, the concrete structure of the durability design of surface protection, to meet the design target reliability index number.

【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級別】：博士
【學(xué)位授予年份】：2013
【分類號】：TU375

【參考文獻】

相關(guān)期刊論文 前10條

1 金祖權(quán);孫偉;李秋義;;碳化對混凝土中氯離子擴散的影響[J];北京科技大學(xué)學(xué)報;2008年08期

2 張鵬;趙鐵軍;郭平功;Wittmann Folker H;;凍融和碳化作用對混凝土氯離子侵蝕的影響[J];東南大學(xué)學(xué)報(自然科學(xué)版);2006年S2期

3 李淑紅;王立成;;多孔建筑材料毛細吸水過程研究進展綜述[J];水利與建筑工程學(xué)報;2010年06期

4 滕海文;黃穎;黃峰洲;霍達;;荷載與環(huán)境因素耦合作用下結(jié)構(gòu)耐久性研究進展[J];工程抗震與加固改造;2011年01期

5 趙尚傳;;海洋環(huán)境中氯離子侵蝕與混凝土碳化誘發(fā)鋼筋銹蝕失效概率的對比分析[J];公路;2008年04期

6 關(guān)宇剛,孫偉,繆昌文;基于可靠度與損傷理論的混凝土壽命預(yù)測模型Ⅰ:模型闡述與建立[J];硅酸鹽學(xué)報;2001年06期

7 方永浩,李志清,張亦濤;持續(xù)壓荷載作用下混凝土的滲透性[J];硅酸鹽學(xué)報;2005年10期

8 余紅發(fā);翁智財;孫偉;陳浩宇;張金花;;礦渣摻量對混凝土氯離子結(jié)合能力的影響[J];硅酸鹽學(xué)報;2007年06期

9 金偉良;張奕;盧振勇;;非飽和狀態(tài)下氯離子在混凝土中的滲透機理及計算模型[J];硅酸鹽學(xué)報;2008年10期

10 李春秋;李克非;;干濕交替下表層混凝土中氯離子傳輸:原理、試驗和模擬[J];硅酸鹽學(xué)報;2010年04期

相關(guān)博士學(xué)位論文 前3條

1 萬小梅;力學(xué)荷載及環(huán)境復(fù)合因素作用下混凝土結(jié)構(gòu)劣化機理研究[D];西安建筑科技大學(xué);2011年

2 范宏;混凝土結(jié)構(gòu)中的氯離子侵入與壽命預(yù)測[D];西安建筑科技大學(xué);2009年

3 李春秋;干濕交替下表層混凝土中水分與離子傳輸過程研究[D];清華大學(xué);2009年

本文編號：1613103