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  本文關(guān)鍵詞： 水泥石 碳化 碳酸鈣 水灰比 相對濕度　出處：《重慶大學(xué)》2014年碩士論文　論文類型：學(xué)位論文

【摘要】：鋼筋銹蝕是混凝土破壞的主要原因之一，我國每年因鋼筋銹蝕引起的混凝土結(jié)構(gòu)損傷破壞的損失達1000億�；炷撂蓟�、氯離子引起鋼筋去鈍化和酸性介質(zhì)是引起鋼筋銹蝕的三個主要原因。由于CO2在大氣環(huán)境中無所不在，所以碳化無所不在，而且，近年來大氣中CO2的濃度有所攀升，進一步加劇了混凝土碳化，因此對混凝土碳化的研究迫在眉睫。水泥石是混凝土中唯一直接發(fā)生碳化的組分，因此，集中力量研究水泥石的碳化是解決碳化問題的關(guān)鍵。 本論文采用化學(xué)分析法，用自制碳化裝置逐層測定了水泥石中碳酸鈣的含量，研究了水灰比、碳化相對濕度、CO2濃度、養(yǎng)護方式、減水劑以及碳化時間等因素對水泥石碳化的影響并研究了其碳化機理，得出的主要結(jié)論如下： 1）隨著水灰比增大，水泥石碳化程度增加，部分碳化區(qū)的寬度也在逐漸增大。水灰比0.45是水泥石抗碳化性能的轉(zhuǎn)折點：當(dāng)水灰比高于或等于0.45時，隨著水灰比增大，水泥石碳化程度加劇顯著，部分碳化區(qū)增加；當(dāng)水灰比小于0.45時，，部分碳化區(qū)很短，水泥石碳化程度低。 2）碳化濕度對于水泥石碳化性影響顯著，環(huán)境濕度接近59%是影響水泥石碳化性能的臨界濕度：當(dāng)濕度高于或等于59%時，部分碳化區(qū)較窄，此時碳化速度是由CO2擴散速度來控制的；而當(dāng)濕度低于59%時，隨著濕度降低水泥石碳化程度顯著增加，且部分碳化區(qū)增加，此時碳化是由化學(xué)反應(yīng)的速度來控制的。 3）CO2濃度越高，水泥石碳化越嚴(yán)重，從實驗過程中還發(fā)現(xiàn)CO2濃度對水泥石碳化性能的影響似乎與碳化濕度有一定關(guān)系，當(dāng)碳化濕度較高時，水泥石碳化程度差別不是很大；當(dāng)碳化濕度較低，CO2濃度較高時，水泥石碳化程度有顯著增加，但是仍需更多試驗來驗證； 4）養(yǎng)護方式不同水泥石碳化性能不同。在飽和Ca(OH)2溶液中養(yǎng)護時，有部分Ca(OH)2進入水泥石結(jié)構(gòu)，有利于水泥石中堿儲備增加，所以與水養(yǎng)相比采用飽和Ca(OH)2溶液養(yǎng)護能提高水泥石抗碳化性。 5）當(dāng)水灰比較低時，摻減水劑對水泥石碳化性能影響短期并不明顯。水灰比較高時，摻加減水劑能夠改善水泥石的抗碳化性能。減水劑摻量的改變對水泥石碳化性能并沒有多大影響。 6）隨著碳化時間的增加，碳化程度在逐漸增加。當(dāng)水灰比較低時碳化深度隨著時間增加而增大的比較緩慢，而水灰比在0.35及更高時，其開始碳化速度較快，后來逐漸減緩。碳化時間和碳化深度有一定的函數(shù)關(guān)系。 7）化學(xué)分析法比酚酞滴定法更能表征真正的碳化程度。
[Abstract]:The corrosion of steel bar is one of the main causes of concrete failure. The damage and damage of concrete structure caused by corrosion of steel bar in China every year is 100 billion. Chloride ion induced deactivation of steel bar and acidic medium are the three main causes of steel bar corrosion. Because CO2 is ubiquitous in atmospheric environment, carbonation is ubiquitous, and the concentration of CO2 in the atmosphere has increased in recent years. The study of concrete carbonization is urgent. Cement stone is the only direct carbonation component in concrete. Therefore, the key to solve the carbonation problem is to concentrate on the carbonization of cement stone. In this paper, the content of calcium carbonate in cement stone was determined layer by layer by means of chemical analysis and self-made carbonization device. The water-cement ratio, the concentration of carbonation relative humidity and CO _ 2, and the curing mode were studied. The effects of water reducer and carbonation time on the carbonation of cement stone are studied. The main conclusions are as follows:. 1) with the increase of water-cement ratio, the carbonization degree of cement stone increases, and the width of partial carbonization zone increases gradually. The water-cement ratio 0.45 is the turning point of cement stone carbonation resistance: when the water-cement ratio is higher than or equal to 0.45, with the increase of water-cement ratio, When the water-cement ratio is less than 0.45, the carbonization area is very short and the carbonization degree of cement stone is low. 2) the influence of carbonation humidity on the carbonation of cement stone is significant. The environmental humidity of 59% is the critical humidity that affects the carbonation performance of cement stone. When the humidity is higher than or equal to 59, the partial carbonization zone is narrow. The carbonation rate is controlled by the diffusion velocity of CO2, but when the humidity is lower than 59, the carbonization degree of cement stone increases significantly with the decrease of humidity, and the carbonization zone increases. In this case, the carbonation rate is controlled by the rate of chemical reaction. (3) the higher the CO _ 2 concentration, the more serious the carbonation of cement stone. It is also found that the influence of CO2 concentration on the carbonation performance of cement stone seems to be related to the carbonation humidity. When the carbonation humidity is higher, the carbonation degree of cement stone is not very different. When the carbonation humidity is lower and the CO _ 2 concentration is higher, the carbonation degree of cement stone increases significantly, but more tests are needed to verify it. 4) when curing in saturated Ca(OH)2 solution, part of Ca(OH)2 enters the structure of cement stone, which is beneficial to increase the alkali reserve in cement stone. Therefore, the carbonation resistance of cement stone can be improved by saturated Ca(OH)2 solution curing. 5) when the cement ash is low, the influence of water reducing agent on the carbonation property of cement stone is not obvious in the short term. The addition of water reducing agent can improve the carbonation resistance of cement stone, but the change of the content of water reducing agent has little effect on the carbonation property of cement stone. 6) with the increase of carbonization time, the carbonization degree increases gradually, and the carbonation depth increases slowly with the increase of time when the water cement ratio is low, and the carbonization rate is faster when the water-cement ratio is 0.35 or higher. The carbonation time has a certain function relation with the carbonization depth. 7) Chemical analysis is more effective than phenolphthalein titration to characterize the true degree of carbonation.
【學(xué)位授予單位】：重慶大學(xué)
【學(xué)位級別】：碩士
【學(xué)位授予年份】：2014
【分類號】：TU528

【參考文獻】

相關(guān)期刊論文 前10條

1 涂永明,呂志濤;應(yīng)力狀態(tài)下混凝土的碳化試驗研究[J];東南大學(xué)學(xué)報(自然科學(xué)版);2003年05期

2 閻培渝;;粉煤灰在復(fù)合膠凝材料水化過程中的作用機理[J];硅酸鹽學(xué)報;2007年S1期

3 史才軍;鄒慶焱;何富強;;二氧化碳養(yǎng)護混凝土的動力學(xué)研究[J];硅酸鹽學(xué)報;2010年07期

4 劉亞芹,張譽,張偉平,王勁,謝華芳;表面覆蓋層對混凝土碳化的影響與計算[J];工業(yè)建筑;1997年08期

5 萬朝均;張廷雷;陳璐圓;夏建民;李有光;;粉煤灰水泥石碳化性能的化學(xué)分析[J];硅酸鹽學(xué)報;2012年08期

6 邵一心;MONKMAN Sean;TRAN Stanley;;混凝土基本組分吸收二氧化碳的能力(英文)[J];硅酸鹽學(xué)報;2010年09期

7 朱安民;;混凝土碳化與鋼筋混凝土耐久性[J];混凝土;1992年06期

8 方t

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