本文選題：混凝土　切入點(diǎn)：耐久性　出處：《西安建筑科技大學(xué)》2013年博士論文　論文類型：學(xué)位論文

【摘要】：寒冷地區(qū)經(jīng)常與水接觸的建筑物或構(gòu)筑物、使用除冰鹽的橋面和路面混凝土常發(fā)生凍融破壞�；炷烈坏┌l(fā)生凍害，治理將相當(dāng)困難，同時(shí)與其它耐久性因素如碳化和氯鹽侵蝕產(chǎn)生復(fù)合疊加作用，嚴(yán)重威脅工程結(jié)構(gòu)的使用壽命。滲透型防水涂料對(duì)基材具有良好防護(hù)效果而又不影響基材的透氣性，受到廣泛的關(guān)注。但是滲透型防水涂料應(yīng)用于受凍融混凝土耐久性防護(hù)并不多見。除了受到環(huán)境因素的影響之外，這些結(jié)構(gòu)或構(gòu)件還要承受機(jī)械荷載的作用。國內(nèi)外尚沒有荷載和凍融耦合作用對(duì)鋼筋混凝土粘結(jié)性能影響的報(bào)道。因此本文主要開展如下幾個(gè)方面的研究工作： （1）基于原材料對(duì)混凝土抗凍性影響分析的基礎(chǔ)上，制作了三種水灰比非引氣混凝土和一種水灰比引氣混凝土，重點(diǎn)研究四種凍融方式情況下混凝土相對(duì)動(dòng)彈性模量和抗壓強(qiáng)度的劣化規(guī)律，對(duì)混凝土凍融破壞機(jī)理進(jìn)行深入探討。結(jié)果表明，凍融方式對(duì)混凝土凍融損傷程度的影響順序?yàn)椋猴査畠鋈冢舅畠?氣凍循環(huán)＞飽水氣凍＞非飽水氣凍。通過混凝土凍結(jié)和融解過程分析，認(rèn)為內(nèi)部毛細(xì)孔水凍結(jié)時(shí)產(chǎn)生的結(jié)冰壓是凍融破壞主要驅(qū)動(dòng)力，降低混凝土內(nèi)部飽水度可以提高混凝土的抗凍性能。 （2）從毛細(xì)吸收理論入手，系統(tǒng)研究混凝土干燥程度、環(huán)境溫度、水浸沒試塊的深度以及環(huán)境的相對(duì)濕度對(duì)混凝土毛細(xì)吸收的影響，從宏觀和微觀角度研究經(jīng)受凍融循環(huán)后混凝土的吸水性和微觀孔結(jié)構(gòu)變化；定量研究受凍融混凝土采用滲透型涂料表面處理后的吸水特性，表面磨損對(duì)吸水性能的影響，分析了受凍融混凝土表面處理后的水分侵入機(jī)理。結(jié)果表明，同一配比混凝土，非引氣混凝土毛細(xì)吸收系數(shù)隨著經(jīng)受循環(huán)次數(shù)增加而成倍數(shù)增大，且增加的趨勢(shì)對(duì)水灰比越大的混凝土愈明顯。受凍融混凝土經(jīng)表面處理后，吸水能力大幅度降低。如果混凝土出現(xiàn)磨損，勢(shì)必會(huì)消減表層混凝土的憎水層厚度，，對(duì)其防水效果產(chǎn)生一定的影響。對(duì)凍融損傷嚴(yán)重的混凝土，憎水層會(huì)變得疏松，使得外部液態(tài)水從“水汽傳輸”逐步過渡到與內(nèi)部非憎水區(qū)的凝結(jié)水形成“水路傳輸”，是凍融損傷混凝土表面防水過早失效的根本原因。 （3）開展實(shí)驗(yàn)室條件下受凍融混凝土氯離子侵入性能試驗(yàn)研究。結(jié)果表明，混凝土凍融損傷對(duì)氯離子擴(kuò)散性能的影響是顯著的�；炷谅入x子擴(kuò)散系數(shù)與凍融損傷符合指數(shù)函數(shù)關(guān)系：D F D0ek �；贔ick第二定律，推導(dǎo)出考慮凍融損傷和凍融剝落影響的氯離子傳輸模型。通過北京舊西直門立交橋和青島膠州灣海底隧道驗(yàn)證和應(yīng)用表明，該模型能夠滿足工程簡(jiǎn)單實(shí)用要求。 （4）研究受凍融混凝土表面防水處理后，室外暴露環(huán)境下抗碳化和氯離子侵入性能，以及快凍環(huán)境下單面鹽凍剝落性能；分析了表面處理后混凝土的鹽凍破壞機(jī)理�；炷猎馐軆鋈谘h(huán)次數(shù)不同，硅烷防護(hù)對(duì)室外暴露混凝土的碳化性能有不同程度的影響。表面處理對(duì)未經(jīng)受凍融循環(huán)作用混凝土提高碳化壽命34%，對(duì)經(jīng)受凍融循環(huán)作用混凝土的抗碳化能力有所降低。無論混凝土是否經(jīng)受凍融，對(duì)抗氯離子侵蝕和混凝土抗鹽凍剝落能力均有良好的防護(hù)效果�？紤]凍融損傷影響系數(shù)、滲透型材料影響系數(shù)修正了碳化深度預(yù)測(cè)模型，給出凍融損傷混凝土抗氯離子侵入所需要的最低硅烷凝膠用量。 （5）設(shè)計(jì)非引氣混凝土和引氣混凝土兩種直拉粘結(jié)試件36個(gè)，通過自行設(shè)計(jì)的持載裝置，實(shí)現(xiàn)了鋼筋持載與凍融循環(huán)的耦合，并通過中心拉拔試驗(yàn)研究鋼筋混凝土粘結(jié)性能的退化規(guī)律；理論計(jì)算證明鋼筋與混凝土溫度線膨脹系數(shù)差異導(dǎo)致界面脫膠的破壞本質(zhì)；揭示鋼筋持載狀態(tài)下鋼筋混凝土粘結(jié)性能加劇退化的機(jī)理。結(jié)果表明，混凝土凍融損傷較小時(shí)，鋼筋持載對(duì)粘結(jié)性能影響較��；當(dāng)混凝土經(jīng)受多次的凍融循環(huán)，凍融損傷度達(dá)到0.5時(shí)，較小的鋼筋持載水平就能夠加速鋼筋與混凝土粘結(jié)性能退化。對(duì)引氣混凝土粘結(jié)試件，持載和凍融復(fù)合疊加作用對(duì)鋼筋混凝土粘結(jié)性能影響不明顯。 （6）研究修復(fù)層材料、修復(fù)層橫向配筋以及凍融對(duì)鋼筋混凝土粘結(jié)性能的影響，并根據(jù)試驗(yàn)結(jié)果提出具有借鑒性的建議。結(jié)果表明，由于SHCC基體具有良好的抗凍能力，材料本身具有良好的耐久性和多縫開裂特性，與老混凝土良好的粘結(jié)性能，能夠提高鋼筋粘結(jié)強(qiáng)度、延性和耐環(huán)境作用能力，并減小凍融循環(huán)作用對(duì)鋼筋粘結(jié)性能的影響，對(duì)延長(zhǎng)結(jié)構(gòu)的剩余使用壽命非常有利。
[Abstract]:Cold regions often come into contact with water in buildings or structures, the use of deicing salt bridge deck pavement concrete and concrete freeze-thaw damage often occurs. Once the occurrence of frost damage, governance will be difficult, and other factors such as durability, carbonation and chloride corrosion to produce a composite additive effect, a serious threat to the service life of engineering structure of permeable. The waterproof coating has good protective effect on the substrate and does not affect the permeability of the material, has been widely concerned. But the permeation type waterproof coating applied to the freeze-thaw durability of concrete protection is rare. In addition to the influence of environmental factors, the role of these structures to withstand mechanical loads. There is no load and the effects of freezing and thawing the coupling effect on the bond performance of reinforced concrete reports at home and abroad. This paper mainly carried out several aspects of the research work are as follows:
(1) based on the analysis of raw materials on the frost resistance of concrete, making three kinds of non air entraining concrete water cement and a water cement ratio of air entraining concrete, focuses on four kinds of frozen thawing deterioration of concrete way under the condition of relative dynamic elastic modulus and compressive strength of concrete, freeze-thaw damage mechanism are discussed. The results show that freeze-thaw of concrete freezing thawing damage degree of influence order is: saturated freezing thawing of frozen water, gas water freezing, freezing cycle > saturated unsaturated water freezing. Through the concrete freezing and thawing process analysis, internal freezing capillary water generated when the ice pressure is frozen destroy the main driving force, reduce the degree of saturation in concrete can improve the frost resistance of concrete.
(2) from the capillary absorption theory of system of concrete drying degree, environmental temperature, relative humidity and water immersion test block depth and environmental influence on concrete capillary absorption, from the perspective of macro and micro research under freeze-thaw cycles water absorption of concrete and micro pore structure change; quantitative study on characteristics of freezing and thawing of concrete the water permeable coating after surface treatment by surface wear effects on water absorption properties, analysis of freezing and thawing of concrete surface treatment after the water invasion mechanism. The results show that the same ratio of concrete, air entraining concrete capillary absorption coefficient with the number of cycles subjected to multiple increases, and the increase of water cement ratio the greater the more obvious. The concrete freezing and thawing of concrete after surface treatment, greatly reduce the water absorption capacity. If the concrete wear, will cut the surface layer of concrete The thickness of the hydrophobic layer has a certain influence on the waterproof effect of freeze-thaw damage of concrete is serious, the hydrophobic layer will become loose, so that the external liquid water from the water vapor transmission "and gradually transition to the internal condensation of water repellent region to form a" water transfer ", is the fundamental reason of freeze thaw damage of concrete surface waterproof premature failure.
(3) to carry out the experimental research on the chloride ion penetration of freeze-thaw concrete under laboratory conditions. The results show that the influence of concrete freezing thawing damage on chloride diffusion is remarkable. The chloride diffusion coefficient of concrete is in accordance with exponential function relation with freeze thaw damage: D F D0ek.
Based on the second law of Fick, a chloride transport model considering the effects of freeze-thaw damage and freeze-thaw spalling is derived. Through the validation and application of Beijing old Xizhimen flyover and Qingdao Jiaozhou Bay Subsea Tunnel, it is shown that the model can meet the simple and practical engineering requirements.
(4) study on the freeze-thaw treatment of concrete surface waterproof, anti carbonation and chloride ion penetration performance of outdoor environment, and fast freezing environment of single side salt scaling properties; analysis of surface treatment of concrete salt freezing damage mechanism of concrete subjected to freeze-thaw cycles. Different silane protection have different effects on the outdoor exposed concrete carbonation. The surface treatment of the action of freezing thawing of concrete carbonation life improve 34%, to withstand freezing and thawing of concrete carbonation resistance decreased. No matter whether the concrete subjected to freeze-thaw resistance, chloride ion erosion and concrete salt freezing stripping ability has a good protective effect. Considering the freeze-thaw damage effect influence of permeability coefficient, material modified prediction model of carbonation depth, minimum silane gel gives the freeze-thaw damage of concrete anti chloride ion needed for The amount of.
(5) the design of the air entraining concrete and air entraining concrete two straight pull adhesive specimen 36, through a self-designed loading device, the steel loading and freezing thawing cycle coupling, and the degradation of pull-out tests of reinforced concrete bonding properties; theoretical calculations show that the temperature of steel and concrete the expansion coefficient difference leads to the destruction of nature of interfacial debonding; steel reinforced concrete bond to reveal the performance of load increasing degradation mechanism. The results show that the damage is small freezing and thawing of concrete, reinforced loading has little effect on the bonding performance; when the concrete subjected to freeze-thaw cycle times, freeze-thaw damage degree is 0.5, smaller bar the load level can accelerate the degradation of bonding properties between reinforcement and concrete. The air entraining concrete specimen, loading and freeze-thaw effect on adhesive properties of composite reinforced concrete impact is unknown Explicit.
(6) study of repair layer materials, repair layer of transverse reinforcement and freeze-thaw effect on bonding property of reinforced concrete, and put forward many valuable suggestions according to the test results. The results show that because the SHCC matrix has good frost resistance, the material itself has good durability and multiple cracking properties and bonding properties of the old concrete good, can improve the steel bond strength, ductility and resistance to environmental capacity, and reduce the effect of freeze-thaw cycle on bond performance, is very beneficial to extend the remaining life of the structure.

【學(xué)位授予單位】：西安建筑科技大學(xué)
【學(xué)位級(jí)別】：博士
【學(xué)位授予年份】：2013
【分類號(hào)】：TU528

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