本文關(guān)鍵詞： 混凝土 硫酸鹽 硫酸根離子分布 擴散模型 強度模型　出處：《深圳大學》2015年碩士論文　論文類型：學位論文

【摘要】：混凝土結(jié)構(gòu)依附的自然環(huán)境均可能含有一定量的硫酸鹽,它們通過多種途徑傳輸?shù)交炷羶?nèi)部造成混凝土自身性能劣化的同時,也降低了與鋼筋共同工作的能力和對鋼筋的保護作用,因此展開對于混凝土抗硫酸鹽侵蝕機理和理論模型的的試驗研究,有利于為混凝土使用壽命(再)設(shè)計奠定重要的理論基礎(chǔ)和依據(jù)。為此,本文展開了長期浸泡環(huán)境下混凝土硫酸鹽侵蝕試驗研究并取得了如下主要研究結(jié)果:(1)文章研究了C25混凝土受10%硫酸鈉溶液一維腐蝕下的強度隨侵蝕齡期劣化規(guī)律,表明受腐蝕混凝土強度前期的提高主要是因為自身水化作用的貢獻,而侵蝕膨脹產(chǎn)物對混凝土強度提高的貢獻最大僅為4%,而后期對混凝土造成的破壞是非常顯著的。(2)通過分層切片、離子滴定等化學手段得到了1%、5%、10%硫酸鹽濃度下C25混凝土和10%硫酸鹽濃度下C50、C70混凝土由表到里的SO42-分布情況,分析了不同硫酸鈉溶液濃度和混凝土強度對混凝土內(nèi)SO42-傳輸?shù)挠绊?表明不同工況下SO42-在混凝土內(nèi)的傳輸劣化機理基本一致,只是演變進程存在差異。(3)利用微觀測試技術(shù)ESEM(環(huán)境電鏡掃描)和EDS(能譜元素分析儀)對受腐蝕混凝土微觀結(jié)構(gòu)形貌和侵蝕產(chǎn)物進行定性分析,揭示了硫酸鹽對混凝土微結(jié)構(gòu)產(chǎn)生的損傷機理和演變規(guī)律。并通過宏微觀相結(jié)合進行深入分析,表明混凝土宏觀力學性能的劣化和硫酸根離子在混凝土內(nèi)部傳輸過程的演化都是微觀結(jié)構(gòu)的變化在宏觀和傳輸方面的反映。(4)以擴散理論為基礎(chǔ),試驗結(jié)果為指導,推導建立了不同工況下硫酸鹽在混凝土內(nèi)部的傳輸模型,包括濃度分布模型和侵蝕深度預測模型,并通過試驗數(shù)據(jù)證明了模型的正確性和適用性。文章最后提出了受腐蝕混凝土平均強度預測模型,并通過自有數(shù)據(jù)和其他文獻數(shù)據(jù)對其進行了驗證;同時基于腐蝕厚度對受腐蝕混凝土截面分析,計算得到了腐蝕層混凝土的平均強度,并建立了與腐蝕層厚度相關(guān)的腐蝕層混凝土平均強度預測模型,另外在已有學者研究基礎(chǔ)上數(shù)學推導了腐蝕層混凝土強度分布模型。
[Abstract]:The natural environment on which concrete structures are attached may contain a certain amount of sulphate, which can be transported to the concrete interior through many ways, which results in the deterioration of concrete's own performance at the same time. It also reduces the ability to work with the steel bar and the protective effect of the steel bar, so the experimental study on the mechanism and theoretical model of the sulfate resistance of concrete has been carried out. It is beneficial to lay an important theoretical foundation and basis for the design of concrete service life. In this paper, the experimental study on sulfate erosion of concrete under long-term immersion environment is carried out and the main results are as follows: 1. The strength of C25 concrete subjected to one-dimensional corrosion of 10% sodium sulfate solution is studied in this paper. The results show that the improvement of the strength of corroded concrete in the early stage is mainly due to the contribution of self-hydration. The maximum contribution of the corrosion expansion product to the strength of concrete is only 4, while the damage caused to the concrete in the later stage is very significant. The distribution of SO42- in C25 concrete at 10% sulphate concentration and in C50C70 concrete at 10% sulfate concentration was obtained by ion titration and other chemical methods. The effects of different sodium sulfate solution concentration and concrete strength on so _ 42- transport in concrete were analyzed. It shows that the transport degradation mechanism of so _ 4 _ 2-- in concrete is basically the same under different working conditions. However, the evolution process is different.) the microstructure and corrosion products of corroded concrete are qualitatively analyzed by means of ESEM (Environmental Electron microscope scanning) and EDS (Energy Spectrum element Analyzer). The damage mechanism and evolution law of sulfate to concrete microstructure are revealed. It is shown that both the deterioration of macroscopic mechanical properties of concrete and the evolution of sulfate ion transport process in concrete are the reflection of the change of microstructure in macroscopic and transport aspects, which is based on the diffusion theory and guided by the experimental results. The transport models of sulfate in concrete under different working conditions are derived, including concentration distribution model and erosion depth prediction model. The model is proved to be correct and applicable by experimental data. Finally, a model for predicting the average strength of corroded concrete is proposed, which is verified by its own data and other literature data. At the same time, the average strength of the corroded concrete is calculated based on the analysis of the section of the corroded concrete based on the corrosion thickness, and the prediction model of the average strength of the corroded concrete is established, which is related to the thickness of the corrosion layer. In addition, the strength distribution model of corroded concrete is derived on the basis of previous research.
【學位授予單位】：深圳大學
【學位級別】：碩士
【學位授予年份】：2015
【分類號】：TU528

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