本文關(guān)鍵詞： 混凝土 耐久性 干濕循環(huán) 硫酸鹽侵蝕 損傷演化方程　出處：《西安建筑科技大學》2013年碩士論文　論文類型：學位論文

【摘要】：混凝土的硫酸鹽侵蝕是一個很常見的耐久性問題，且造成的損失很嚴重。國內(nèi)外學者已經(jīng)進行了大量研究。但由于考慮的因素、遵循的標準不同，相互之間有比較大的差異性，可以說目前對混凝土硫酸鹽侵蝕的研究是非�；靵y的。硫酸鹽和干濕循環(huán)共同作用時對混凝土造成的損傷比兩種條件單獨作用時更大，且實際環(huán)境中的腐蝕都不是單一因素作用，研究兩種因素共同作用的情況將更有實際意義。 本文采用的試驗制度是先將混凝土試塊浸泡7d，然后自然晾置8d，試驗共計360d。每隔30d對試塊進行以下指標的測試：1）抗壓強度；2）質(zhì)量損失；3）動彈性模量；4）混凝土損傷層厚度和損傷層超聲波速。最后使用掃描電子顯微鏡觀察腐蝕產(chǎn)物的生成情況。試驗考察了水膠比、Na2SO4溶液濃度和礦物摻合料的影響，結(jié)合宏觀試驗和電鏡掃描結(jié)果對混凝土的損傷機理進行了分析，建立了基于動彈模量Ed的損傷演化方程。 綜合分析結(jié)果，將混凝土在干濕循環(huán)和硫酸鹽侵蝕共同作用下的腐蝕過程分為四個階段：第一個階段是硫酸鹽物理結(jié)晶的膨脹應力起主要作用，，混凝土內(nèi)部有少量裂縫產(chǎn)生，密實性有所下降，造成混凝土的動彈模量降低。由于混凝土的水化作用，混凝土的強度有所增加；第二個階段化學腐蝕不斷加重，腐蝕產(chǎn)物增多，部分地填充了混凝土的孔隙，延緩混凝土密實性的降低，這一階段混凝土的質(zhì)量和強度都開始下降，而動彈模量降低得比之前慢；第三階段是由于物理、化學作用的加劇致使各個性能指標的退化，混凝土的質(zhì)量、動彈模量和抗壓強度都出現(xiàn)下降；第四階段是加速劣化階段，混凝土試塊表層剝蝕和脫落，邊角出現(xiàn)大量裂縫，這個階段內(nèi)混凝土的各個指標均加速降低。 本文第五章從損傷層厚度的角度對混凝土的損傷情況進行了分析。根據(jù)超聲波在混凝土中的傳播速度計算混凝土的損傷層厚度。損傷層厚度的變化和宏觀試驗結(jié)果大體相符合，損傷層厚度的變化基本上可以反映混凝土的損傷情況。
[Abstract]:Sulfate erosion of concrete is a very common durability problem, and the loss caused by it is very serious. Many domestic and foreign scholars have done a lot of research. However, due to the factors considered, the standard is different. There are great differences between each other. It can be said that the present study on sulfate erosion of concrete is very confusing. The damage to concrete caused by the combined action of sulfate and dry and wet cycle is greater than that of the two conditions alone. And the corrosion in the actual environment is not a single factor, so it will be more meaningful to study the interaction of the two factors. The test system adopted in this paper is to soak the concrete test block for 7 days, then set it naturally for 8 days, for a total of 360 days. The compressive strength of the test piece is tested on the following indexes: 1) every 30 days; 2) quality loss; 3) dynamic elastic modulus; 4) thickness of concrete damage layer and ultrasonic velocity of damage layer. Finally, the formation of corrosion products was observed by scanning electron microscope (SEM). The water-binder ratio was investigated experimentally. The damage mechanism of concrete was analyzed by Na2SO4 solution concentration and mineral admixture. The damage evolution equation based on dynamic modulus Ed was established. The results show that the corrosion process of concrete under the combined action of wet and dry cycle and sulfate erosion is divided into four stages: the first stage is the expansion stress of sulfate physical crystallization. There are a few cracks in the concrete and the compactness decreases, which results in the decrease of the dynamic modulus of the concrete. The strength of the concrete increases due to the hydration of the concrete. In the second stage, the chemical corrosion becomes more and more serious, and the corrosion products increase, partly filling the pores of the concrete, delaying the reduction of the compactness of the concrete, and the quality and strength of the concrete begin to decline in this stage. However, the dynamic modulus decreased more slowly than before. The third stage is the deterioration of each performance index due to the aggravation of physical and chemical action, and the decrease of concrete quality, dynamic modulus and compressive strength. In the 4th stage, the accelerated deterioration stage, the surface erosion and shedding of the concrete test block, and a large number of cracks appear in the edge corner, and each index of the concrete is accelerated to decrease in this stage. In chapter 5th, the damage of concrete is analyzed from the point of view of the thickness of damage layer. According to the velocity of ultrasonic wave propagation in concrete, the thickness of damage layer of concrete is calculated. The results were consistent. The change of damage layer thickness can basically reflect the damage of concrete.
【學位授予單位】：西安建筑科技大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TU528.0

【參考文獻】

相關(guān)期刊論文 前9條

1 周俊龍,楊德斌;粉煤灰水泥砂漿抗硫酸鹽侵蝕的研究[J];粉煤灰綜合利用;2002年03期

2 亢景富;混凝土硫酸鹽侵蝕研究中的幾個基本問題[J];混凝土;1995年03期

3 馬保國,賀行洋,蘇英,陳友治,李永鑫,朱洪波;內(nèi)鹽湖環(huán)境中混凝土硫酸鹽侵蝕破壞研究[J];混凝土;2001年04期

4 賀傳卿,李永貴,王懷義,高建新;硫酸鹽對水泥混凝土的侵蝕及其防治措施[J];混凝土;2003年03期

5 高禮雄;榮輝;劉金革;;鋇鹽對混凝土抗硫酸鹽侵蝕的有效性研究[J];混凝土;2007年03期

6 陳劍毅;肖燁;胡明玉;李建平;;復雜環(huán)境下混凝土改性問題研究[J];混凝土;2011年05期

7 張亞梅;陳勝霞;高岳毅;;浸-烘循環(huán)作用下橡膠水泥混凝土的性能研究[J];建筑材料學報;2005年06期

8 高蘊昕,鄭泉水,余壽文;各向同性彈性損傷的雙標量描述[J];力學學報;1996年05期

9 王起才;南疆鐵路橋梁工程混凝土抗侵蝕試驗研究[J];蘭州鐵道學院學報;1997年04期

相關(guān)博士學位論文 前2條

1 劉贊群;混凝土硫酸鹽侵蝕基本機理研究[D];中南大學;2010年

2 徐惠;硫酸鹽腐蝕下混凝土損傷行為研究[D];中國礦業(yè)大學;2012年

本文編號：1465521