本文關(guān)鍵詞： 混凝土 硫酸鹽 硫酸根離子分布 擴(kuò)散模型 強(qiáng)度模型　出處：《深圳大學(xué)》2015年碩士論文　論文類(lèi)型：學(xué)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(guò)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(shí),也降低了與鋼筋共同工作的能力和對(duì)鋼筋的保護(hù)作用,因此展開(kāi)對(duì)于混凝土抗硫酸鹽侵蝕機(jī)理和理論模型的的試驗(yàn)研究,有利于為混凝土使用壽命(再)設(shè)計(jì)奠定重要的理論基礎(chǔ)和依據(jù)。為此,本文展開(kāi)了長(zhǎng)期浸泡環(huán)境下混凝土硫酸鹽侵蝕試驗(yàn)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(qiáng)度隨侵蝕齡期劣化規(guī)律,表明受腐蝕混凝土強(qiáng)度前期的提高主要是因?yàn)樽陨硭饔玫呢暙I(xiàn),而侵蝕膨脹產(chǎn)物對(duì)混凝土強(qiáng)度提高的貢獻(xiàn)最大僅為4%,而后期對(duì)混凝土造成的破壞是非常顯著的。(2)通過(guò)分層切片、離子滴定等化學(xué)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(qiáng)度對(duì)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(jī)理基本一致,只是演變進(jìn)程存在差異。(3)利用微觀測(cè)試技術(shù)ESEM(環(huán)境電鏡掃描)和EDS(能譜元素分析儀)對(duì)受腐蝕混凝土微觀結(jié)構(gòu)形貌和侵蝕產(chǎn)物進(jìn)行定性分析,揭示了硫酸鹽對(duì)混凝土微結(jié)構(gòu)產(chǎn)生的損傷機(jī)理和演變規(guī)律。并通過(guò)宏微觀相結(jié)合進(jìn)行深入分析,表明混凝土宏觀力學(xué)性能的劣化和硫酸根離子在混凝土內(nèi)部傳輸過(guò)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(kuò)散理論為基礎(chǔ),試驗(yàn)結(jié)果為指導(dǎo),推導(dǎo)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(yù)測(cè)模型,并通過(guò)試驗(yàn)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(qiáng)度預(yù)測(cè)模型,并通過(guò)自有數(shù)據(jù)和其他文獻(xiàn)數(shù)據(jù)對(duì)其進(jìn)行了驗(yàn)證;同時(shí)基于腐蝕厚度對(duì)受腐蝕混凝土截面分析,計(jì)算得到了腐蝕層混凝土的平均強(qiáng)度,并建立了與腐蝕層厚度相關(guān)的腐蝕層混凝土平均強(qiáng)度預(yù)測(cè)模型,另外在已有學(xué)者研究基礎(chǔ)上數(shù)學(xué)推導(dǎo)了腐蝕層混凝土強(qiáng)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(xué)位授予單位】：深圳大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2015
【分類(lèi)號(hào)】：TU528

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