本文選題：混凝土 + 鹽蝕　； 參考：《吉林大學(xué)》2017年碩士論文

【摘要】：混凝土遭受鹽類侵蝕是引起混凝土結(jié)構(gòu)失效的一種耐久性破壞方式。在不同類鹽蝕作用下,混凝土構(gòu)筑物往往在遠(yuǎn)未達(dá)到設(shè)計(jì)使用年限的情況下就失效破壞,其服役期工作性能也大幅降低,這必將嚴(yán)重制約水泥基復(fù)合材料在侵蝕性環(huán)境中的實(shí)際工程應(yīng)用。在我國東北鹽漬土地區(qū)、西北鹽湖地區(qū)以及東南沿海地區(qū),混凝土結(jié)構(gòu)受到鹽漬土、侵蝕性地表水以及海水侵蝕,導(dǎo)致混凝土結(jié)構(gòu)發(fā)生耐久性破壞的工程實(shí)例已經(jīng)屢見不鮮。這些區(qū)域混凝土構(gòu)筑物受耐久性破壞的侵蝕性離子主要是SO42-、Cl-和HCO3-離子。不同類鹽蝕引起混凝土細(xì)觀損傷、結(jié)構(gòu)性能劣化、耐久性破壞的作用機(jī)理和效果截然不同,因此開展混凝土受不同鹽類侵蝕的宏-細(xì)觀損傷機(jī)理研究是混凝土結(jié)構(gòu)耐久性研究中亟待解決的科學(xué)問題,具有十分重要的研究前景。在實(shí)際工程結(jié)構(gòu)中,由于混凝土內(nèi)部結(jié)構(gòu)孔隙的存在,各種鹽離子的侵蝕滲入會(huì)對(duì)其物理力學(xué)性能產(chǎn)生巨大影響。侵蝕環(huán)境中混凝土的細(xì)觀結(jié)構(gòu)變化決定了混凝土宏觀的物理力學(xué)性能,由于鹽類隨水分在混凝土內(nèi)部遷移、析出、結(jié)晶、膨脹導(dǎo)致混凝土細(xì)觀結(jié)構(gòu)破壞,從而引起宏觀的耐久性破壞,故必須將宏觀物理現(xiàn)象和細(xì)觀結(jié)構(gòu)損傷聯(lián)系起來進(jìn)行研究。本文依托國家自然科學(xué)基金重點(diǎn)項(xiàng)目(41430642)、國家自然科學(xué)基金青年項(xiàng)目(51108207)、中國博士后科學(xué)基金項(xiàng)目(2015M581403)和凍土工程國家重點(diǎn)實(shí)驗(yàn)室開放基金(SKLFSE201514)的資助,針對(duì)東北鹽漬土地區(qū)獨(dú)特的土壤環(huán)境,首次將碳酸氫根作為混凝土主要的侵蝕性離子,進(jìn)行了碳酸氫鹽侵蝕下的混凝土宏-細(xì)觀損傷機(jī)理研究。通過混凝土受SO42-、HCO3-侵蝕的干濕循環(huán)試驗(yàn)、長期浸泡試驗(yàn)和SEM試驗(yàn),將宏觀物理力學(xué)性能與細(xì)觀結(jié)構(gòu)分析相結(jié)合,對(duì)不同類鹽蝕混凝土的宏-細(xì)觀損傷機(jī)理進(jìn)行深入分析。試驗(yàn)考慮的影響因素包括侵蝕性陰離子類別、侵蝕溶液濃度、混凝土水膠比、侵蝕時(shí)間、含氣量等,在試驗(yàn)中觀測混凝土相對(duì)動(dòng)彈性模量、質(zhì)量損失等指標(biāo)。通過試驗(yàn)分析,混凝土結(jié)構(gòu)處于侵蝕性土壤與空氣交界面或侵蝕性地下水及地表水與空氣交界處侵蝕破壞最嚴(yán)重。復(fù)合鹽(SO42-和HCO3-)對(duì)混凝土的耐久性破壞最嚴(yán)重,SO42-對(duì)混凝土的耐久性破壞次之,HCO3-最弱。擬合得出了干濕循環(huán)環(huán)境中混凝土相對(duì)動(dòng)彈性模量與侵蝕時(shí)間之間的函數(shù)關(guān)系,從而能夠?qū)}蝕環(huán)境下混凝土材料的壽命進(jìn)行有效預(yù)測。另外,通過大量SEM試驗(yàn),對(duì)單鹽侵蝕及復(fù)合鹽侵蝕狀態(tài)下的混凝土的細(xì)觀結(jié)構(gòu)損傷進(jìn)行了研究,并將受鹽蝕混凝土的宏觀物理力學(xué)性能與細(xì)觀結(jié)構(gòu)分析相結(jié)合,為揭示混凝土結(jié)構(gòu)受鹽類侵蝕破壞的本質(zhì)做了有益嘗試。
[Abstract]:Salt erosion of concrete is a kind of durability failure mode that causes failure of concrete structure. Under the action of different kinds of salt corrosion, concrete structures often fail and destroy under the circumstances of far less than the design life, and the service performance of concrete structures is also greatly reduced. This will seriously restrict the practical engineering application of cement-based composites in erosive environment. In the saline soil area of northeast China, the northwest salt lake area and the southeast coastal area, the concrete structure has been eroded by saline soil, erosive surface water and sea water, which has caused the durability damage of concrete structure. The erosive ions of concrete structures in these regions are mainly so _ 42-O _ (Cl-) and HCO _ 3- ions. The mechanism and effect of concrete meso-damage, structural performance deterioration and durability damage caused by different kinds of salt corrosion are very different. Therefore, it is an urgent scientific problem to study the macro-meso damage mechanism of concrete subjected to different salt erosion, which has a very important research prospect. In practical engineering structures, the physical and mechanical properties of concrete are greatly influenced by the erosion and infiltration of various salt ions due to the existence of pores in the internal structure of concrete. The macroscopic physical and mechanical properties of concrete are determined by the variation of the meso-structure of concrete in the erosive environment. Because the salts migrate, precipitate, crystallize and expand with the water in the concrete, the micro-structure of the concrete is destroyed. So it is necessary to study the macroscopic physical phenomena and the damage of mesoscopic structures. This paper relies on the support of the key projects of the National Natural Science Foundation of China 41430642U, the Youth Project of the National Natural Science Foundation of China 51108207U, the China Post-doctoral Science Foundation Project (2015M581403) and the State key Laboratory of Frozen soil Engineering (SKLFSE201514). In view of the special soil environment in the saline soil area of Northeast China, the mechanism of macro- meso-damage of concrete under bicarbonate erosion was studied by using bicarbonate as the main corrosive ion of concrete for the first time. Through dry-wet cycle test, long-term immersion test and SEM test of concrete corroded by so _ 42-HCO _ 3-, macroscopical physical and mechanical properties were combined with meso-structure analysis to deeply analyze the macro-meso-damage mechanism of different kinds of salt corroded concrete. The influencing factors considered in the experiment include the category of erosive anions, the concentration of erosive solution, the ratio of water to binder of concrete, the time of erosion and the amount of air. The relative dynamic modulus of elasticity and mass loss of concrete are observed in the test. Through experimental analysis, the erosion damage of concrete structure is the most serious at the interface between soil and air or erosive groundwater and the interface between surface water and air. Composite salt so _ 42- and HCO _ 3) have the most serious durability damage to concrete (so _ 42-) and HCO _ 3- is the weakest. The functional relationship between the relative dynamic elastic modulus and the erosion time of concrete in dry-wet cycle environment is obtained, which can effectively predict the life of concrete materials under salt corrosion environment. In addition, through a large number of SEM tests, the microstructural damage of concrete under the condition of single salt erosion and complex salt erosion is studied, and the macroscopic physical and mechanical properties of the concrete subjected to salt corrosion are combined with the meso-structure analysis. A useful attempt has been made to reveal the nature of concrete structure damaged by salt erosion.
【學(xué)位授予單位】：吉林大學(xué)
【學(xué)位級(jí)別】：碩士
【學(xué)位授予年份】：2017
【分類號(hào)】：TU528

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