本文關鍵詞： 混凝土 內部相對濕度 自干燥 水分擴散 抗壓強度 化學結合水 氫氧化鈣 孔結構　出處：《青島理工大學》2013年碩士論文　論文類型：學位論文

【摘要】：混凝土材料以其卓越的性能成為目前應用最廣、使用最成功的結構材料，而混凝土的宏微觀性能受其內部相對濕度（Iternal Relative Humidity, IRH）變化的影響，研究早齡期混凝土由水分擴散和自干燥引起的IRH變化規(guī)律，混凝土IRH隨環(huán)境演變規(guī)律，以及自干燥環(huán)境下早齡期混凝土內部濕度場與力學性能、化學結合水含量、氫氧化鈣（CH）含量以及孔結構發(fā)展特征之間的關系，既具有理論意義又具有實踐意義。本文通過試驗研究與分析，取得了以下研究結論。 一、研究了恒溫恒濕環(huán)境中，早齡期混凝土由水分擴散和自干燥引起的IRH變化規(guī)律。研究表明： （1）恒溫恒濕環(huán)境中混凝土IRH的衰減由自干燥和水分擴散共同影響決定，衰減速度先快后慢，齡期28d內IRH衰減值可達到112d總衰減值的80%以上。 （2）W/C越大，僅由自干燥引起的混凝土IRH的衰減程度越小，僅由水分擴散引起的衰減程度越大；超細礦粉（GGBS）能使兩種原因引起的混凝土IRH的衰減程度有所增大，而粉煤灰（FA）可大大降低IRH的衰減程度；測試深度越大，由水分擴散引起的混凝土IRH衰減程度越小。 （3）隨著W/C的增大，自干燥對混凝土IRH下降的影響比例逐漸減小，，而水分擴散的影響比例逐漸增大；摻50%FA的混凝土受水分擴散影響較大，其他主要受自干燥影響；測試深度越大，水分擴散的影響比例越小。 二、研究了海洋環(huán)境和模擬海洋環(huán)境下混凝土IRH的變化情況。研究表明： （1）海洋大氣區(qū)和浪濺區(qū)環(huán)境濕度對混凝土IRH有重要影響，混凝土IRH會隨著環(huán)境濕度變化而變化，但混凝土內部濕度響應較慢。 （2）在烘干過程中，測試深度越小，混凝土IRH開始下降的越早，下降的速度和幅度越大，且4.0cm處的濕度在測定的時間內沒有達到平衡，說明混凝土IRH變化存在時間上的滯后效應。 （3）在吸水過程中，距離吸水面越近，混凝土IRH增加的越早，增長速度越快，達到飽水狀態(tài)所需的時間越短；混凝土IRH的增長是先由慢變快，而后又逐漸減慢并最終達到100%的過程。 （4）在干濕循環(huán)過程中，低潮位附近的混凝土IRH將達到飽和狀態(tài)（IRH=100%），但表面層IRH則隨環(huán)境濕度變化而變化；而高潮位附近的混凝土IRH將處于非飽和狀態(tài)（IRH100%），易導致海水中腐蝕離子快速滲入。 三、研究了自干燥環(huán)境下混凝土力學性能、化學結合水含量、CH含量以及孔結構的發(fā)展與混凝土IRH的關系。研究表明： （1）自干燥環(huán)境下混凝土IRH的逐漸下降階段與化學結合水含量、抗壓強度的變化及CH含量下降階段都具有顯著的線性相關性。自干燥環(huán)境下混凝土IRH與化學結合水含量、抗壓強度及CH含量的定量關系可依次用式y(tǒng)=ahs+b描述。 （2）自干燥環(huán)境下混凝土IRH變化與最可幾孔徑及總孔隙率的定量關系均可用式y(tǒng)=A*exp(-x/t)+y0表示，IRH與最可幾孔徑具有顯著的非線性關系，但與總孔隙率之間的非線性相關性較弱；IRH變化與平均孔徑的定量關系可用R=ahs+b表示，具有較好的線性關系。
[Abstract]:The concrete materials become the most widely used for its excellent performance, the use of structural materials for the most successful, and the macro and micro properties of concrete by the internal relative humidity (Iternal Relative, Humidity, IRH) the impact of changes in early age concrete research by moisture diffusion and self dry IRH variation of dryness caused by the evolution of concrete IRH with the environment, and since the dry environment of early age concrete internal humidity field and mechanical properties, chemical combined water content, calcium hydroxide (CH) the relationship between content and pore structure characteristics, has both theoretical significance and practical significance. This paper through experimental research and analysis, obtained the following conclusions.
First, the change law of IRH in early age concrete caused by water diffusion and self drying in constant temperature and constant humidity environment is studied.
(1) the attenuation of concrete IRH in constant temperature and humidity environment is determined by the co effect of self drying and moisture diffusion. The attenuation speed is fast and slow. The attenuation value of IRH in 28d reaches 80% of the total 112d attenuation.
(2) W/C is larger, only by the degree of attenuation of IRH concrete self desiccation caused by the smaller, only by the diffusion of water caused by the greater degree of attenuation; ultrafine slag (GGBS) concrete degree of attenuation of IRH can make the two causes of the increase, and fly ash (FA) can greatly reduce the degree of attenuation of IRH the test; depth increases, the concrete moisture diffusion caused by IRH decay degree is smaller.
(3) with the increase of W/C, since the effects of drying on the concrete of the decrease of IRH ratio decreased, and the effect of ratio of moisture diffusion increases; influence of moisture diffusion of concrete mixed with 50%FA, the other is mainly affected by self desiccation effect; test depth increases, the influence of water diffusion ratio is smaller.
Two, the changes of the concrete IRH in the marine environment and the simulated marine environment are studied.
(1) the environmental humidity in the marine atmospheric area and splash zone has an important influence on the concrete IRH. The concrete IRH will change with the change of the environmental humidity, but the humidity response inside the concrete is slower.
(2) during the drying process, the smaller the test depth, the earlier the concrete IRH began to fall. The greater the speed and the magnitude of the decrease, the 4.0cm humidity did not reach equilibrium in the time of testing. This indicates that there is time lag effect on the change of concrete IRH.
(3) in the process of absorbing water, the closer the distance to the suction surface is, the earlier the concrete IRH increases, the faster the growth rate is, the shorter the time to reach the satiety state. The growth of concrete IRH is slow and fast, and then gradually slows down and finally reaches 100%.
(4) in the dry wet cycle process, concrete IRH near the low tide will reach saturation (IRH=100%), but the surface layer of IRH with humidity change; and the tide near the concrete IRH in the unsaturated state (IRH100%), easily lead to seawater corrosion from rapid infiltration.
Three, the relationship between the mechanical properties of concrete, the content of chemical combined water, the content of CH and the development of the pore structure and the relationship between the pore structure and the concrete IRH are studied.
(1) since the dry environment of concrete IRH gradually decreased and the chemical combined water content changes, and the content of CH compressive strength decline stage has a significant linear correlation between the dry environment. Since the concrete IRH and the chemical combined water content, the compressive strength and the content of CH quantitative relationship can be followed by the y=ahs+b description.
(2) since the quantitative relationship between the changes of IRH concrete under dry environment with most pore size and porosity can be y=A*exp (-x/t) +y0, IRH and the pore has a significant nonlinear relationship, but weak correlation between nonlinear and total porosity; quantitative relationship between the change of IRH and the average pore size of the available R=ahs+b that has a good linear relationship.

【學位授予單位】：青島理工大學
【學位級別】：碩士
【學位授予年份】：2013
【分類號】：TU528

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