本文選題：鋼筋混凝土 + 耐久性��； 參考：《三峽大學(xué)》2014年碩士論文

【摘要】：鋼筋銹蝕是導(dǎo)致混凝土結(jié)構(gòu)耐久性喪失的首要原因，目前，對鋼筋銹蝕的研究都采用方法簡單、周期短、成本低的通電加速銹蝕法，但眾多學(xué)者對此法的控制因素及銹蝕效果說法不一。因此，有必要對通電加速銹蝕法進(jìn)行系統(tǒng)地研究，并提出銹蝕效果與自然銹蝕最為相似的控制指標(biāo)。 在混凝土保護(hù)層開裂前后兩個(gè)階段，通過控制三個(gè)變量即不同的鋼筋類型、不同的電流密度、不同的通電方式對通電加速銹蝕試驗(yàn)方法進(jìn)行了研究，同時(shí)用同種材質(zhì)的裸筋對比分析了法拉第電解定律對鋼筋銹蝕率預(yù)估的準(zhǔn)確性。試驗(yàn)過程中，發(fā)明了一種防水效果較好的混凝土表面防水應(yīng)變片，并專門設(shè)計(jì)了一種多功能混凝土試件劈拉裝置使得試驗(yàn)順利進(jìn)行。 研究結(jié)果表明，在相同的通電條件下，混凝土中鋼筋通電銹蝕后實(shí)測銹蝕率均低于理論銹蝕率，而裸筋通電加速銹蝕后，實(shí)測值均高于理論值，但實(shí)測銹蝕率與用法拉第電解定律計(jì)算所得理論銹蝕率具有很好的相關(guān)性，不同工況下的實(shí)測銹蝕率可由理論銹蝕率乘以相應(yīng)系數(shù)得出。 在相同氯鹽濃度和電流密度下，光圓裸筋在通電加速銹蝕后銹蝕效率比變形裸筋更高，造成二者銹蝕效率不同的本質(zhì)原因主要是兩種鋼筋的表面形狀不同。在相同氯鹽濃度和鋼筋類型下，低電流密度時(shí)裸筋的銹蝕效率比高電流密度更高；在相同的鋼筋類型和電流密度下，氯鹽濃度的不同對裸筋銹蝕效率的影響并不明顯。 鋼筋混凝土試件通電銹蝕保護(hù)層開裂前和開裂時(shí)兩個(gè)銹蝕階段，，在其他條件都相同的情況下，全浸泡通電方式加速銹蝕時(shí)鋼筋的銹蝕效率最高，半浸泡次之，電遷移銹蝕效率最低；在相同氯鹽濃度和電流密度下，光圓鋼筋的銹蝕效率比變形鋼筋更高，與裸筋通電銹蝕結(jié)論相同。 針對試驗(yàn)過程中產(chǎn)生的銹蝕鋼筋及其產(chǎn)物分別進(jìn)行了銹蝕形態(tài)和銹蝕成分的分析，分析結(jié)果表明：混凝土中鋼筋的銹蝕部位與負(fù)極放置位置及電流走向相關(guān)，因此，在通電過程中，可人為控制鋼筋的銹蝕效果。鋼筋混凝土試件通電加速銹蝕保護(hù)層開裂前銹蝕產(chǎn)物含有更多的Fe3O4，而保護(hù)層開裂時(shí)各工況的銹蝕產(chǎn)物含有更多的Fe2O3和FeO(OH)；全浸泡通電方式下銹蝕產(chǎn)物多為Fe2O3，半浸泡通電方式下銹蝕產(chǎn)物多為Fe3O4，電遷移通電后銹蝕產(chǎn)物成分主要為Fe(OH)2、FeO(OH)；三種不同通電方式下得到的銹蝕產(chǎn)物的形貌特征也存在差異；通電銹蝕產(chǎn)物密實(shí)度低于自然銹蝕產(chǎn)物，且自然銹蝕產(chǎn)物主要為Fe和O的化合物，而通電銹蝕產(chǎn)物主要為鐵銹和水泥凝膠體的混合體。根據(jù)相關(guān)公式推導(dǎo)，得到銹蝕產(chǎn)物體積膨脹率的計(jì)算公式，由此公式可知其體積膨脹率僅與各銹蝕成分的密度、膨脹率以及質(zhì)量百分比有關(guān)，不同工況下鋼筋銹蝕產(chǎn)物的體積膨脹率較為接近，約為2.05~2.63之間。
[Abstract]:The corrosion of steel bar is the primary cause of the loss of durability of concrete structure. At present, the corrosion of steel bar is studied by means of simple method, short period and low cost. However, many scholars have different opinions on the controlling factors and corrosion effect of this method. Therefore, it is necessary to systematically study the method of electric accelerated corrosion, and put forward the control index which is the most similar to natural corrosion. In the two stages before and after the cracking of the concrete cover, by controlling three variables, namely, different types of steel bars, different current density and different ways of electrification, the test method of electric accelerated corrosion is studied. At the same time, the accuracy of Faraday's law of electrolysis to estimate the corrosion rate of steel bar is analyzed by comparison of bare bars of the same material. In the course of the test, a kind of waterproofing strain gauge with better waterproof effect was invented, and a multi-function concrete specimen splitting and drawing device was specially designed to make the test proceed smoothly. The results show that under the same electric condition, the measured corrosion rate of reinforced bars in concrete is lower than the theoretical corrosion rate, and the measured corrosion rate is higher than the theoretical value after the electric corrosion of bare bars is accelerated. However, there is a good correlation between the measured corrosion rate and the theoretical corrosion rate calculated by Faraday electrolysis law. The measured corrosion rate under different working conditions can be obtained by multiplying the theoretical corrosion rate by the corresponding coefficient. Under the same chloride concentration and current density, the corrosion efficiency of the bare bars is higher than that of the deformed bars. The main reason for the difference in corrosion efficiency between the two bars is that the surface shapes of the two kinds of bars are different. Under the same chloride concentration and reinforcement type, the corrosion efficiency of bare bars at low current density is higher than that of high current density, but the effect of chloride concentration on the corrosion efficiency of bare bars is not obvious under the same reinforcement type and current density. Under the same other conditions, the corrosion efficiency of the steel bar is the highest when the electric corrosion protective layer of the reinforced concrete specimen is accelerated by the full immersion and electrified mode, and the second is the semi-immersion, when the corrosion stage is before and during the corrosion of the electric corrosion protective layer of the reinforced concrete specimen, and when the other conditions are the same, the corrosion efficiency of the steel bar is the highest. Under the same chloride concentration and current density, the corrosion efficiency of light circular steel bar is higher than that of deformed steel bar, which is the same as that of bare steel bar. The corrosion morphology and corrosion composition of the corroded steel bar and its products produced during the test are analyzed respectively. The results show that the corrosion position of the steel bar in concrete is related to the position of the negative pole and the direction of the current, so the corrosion position of the steel bar in the concrete is related to the position of the negative pole and the direction of the current. In the process of electrification, the corrosion effect of steel bars can be artificially controlled. There are more Fe _ 3O _ 4 and Fe _ 2O _ 3 in the corrosion products under different conditions before the corrosion of the protective layer is accelerated by electrification of the reinforced concrete specimen. The corrosion product contains more Fe _ 3O _ 4 and more Fe _ 2O _ 3 and Fe _ 2O _ 3 during the cracking of the protective layer. The corrosion products are mostly Fe _ 2O _ 3 under full immersion mode and Fe _ 3O _ 4 under semi-immersion electrification mode, and the main corrosion products after electromigration are Fe _ 2O _ (2) O _ (2) O _ (2) O _ (2) O _ (2) O _ (2) O _ (2) O _ (2) O _ (2) O _ (2), and the morphologies of the corrosion products obtained under three different modes of electrification are also different. The compactness of the corrosion product is lower than that of the natural corrosion product, and the natural corrosion product is mainly Fe and O compounds, while the electric corrosion product is mainly a mixture of rust and cement gel. According to the related formula, the calculation formula of volume expansion rate of corrosion product is obtained. The volume expansion rate is only related to the density, expansion rate and mass percentage of each corroded component. The volume expansion ratio of the corrosion products of steel bars under different working conditions is close to that of 2.05 ~ 2.63.
【學(xué)位授予單位】：三峽大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU375

【引證文獻(xiàn)】

相關(guān)期刊論文 前1條

1 徐港;鮑浩;王青;徐浩銘;;混凝土中鋼筋銹蝕產(chǎn)物模量特性研究[J];水利水運(yùn)工程學(xué)報(bào);2014年05期

本文編號：2019748