本文選題：混凝土 + 耐久性　； 參考：《廣西大學(xué)》2017年碩士論文

【摘要】：硫酸鹽侵蝕是引發(fā)混凝土結(jié)構(gòu)耐久性損傷破壞的重要因素之一,侵蝕至混凝土結(jié)構(gòu)內(nèi)部的硫酸根離子可以與水化鋁酸鈣等水泥水化產(chǎn)物發(fā)生化學(xué)反應(yīng),生成鈣釩石等膨脹性物質(zhì),當(dāng)膨脹應(yīng)變和應(yīng)力超過(guò)了混凝土結(jié)構(gòu)的極限抗拉強(qiáng)度,膨脹性裂縫隨之產(chǎn)生,并隨著侵蝕周期的延長(zhǎng)而不斷發(fā)展,最終導(dǎo)致混凝土結(jié)構(gòu)的耐久性失效。本文主要從試驗(yàn)研究和數(shù)值模擬研究?jī)煞矫婀餐骄苛肆蛩猁}侵蝕混凝土的擴(kuò)散-反應(yīng)行為,并進(jìn)行了相應(yīng)的結(jié)構(gòu)耐久性分析及服役壽命預(yù)測(cè)。主要研究?jī)?nèi)容包括:(1)提出了硫酸鹽二維侵蝕的試驗(yàn)方法,并開(kāi)展了相應(yīng)的硫酸鹽二維侵蝕的試驗(yàn)研究,試驗(yàn)中通過(guò)開(kāi)展侵蝕后混凝土中硫酸鹽的濃度測(cè)試和MTS力學(xué)測(cè)試分別獲得了硫酸根離子侵入量及受硫酸鹽侵蝕后的試塊應(yīng)力-應(yīng)變等數(shù)據(jù),并分析了膠凝材料的組份、養(yǎng)護(hù)時(shí)間以及粗骨料對(duì)硫酸鹽侵蝕的影響規(guī)律。從硫酸根離子侵入量以及抗壓強(qiáng)度值來(lái)看,研究表明:在12周的侵蝕周期內(nèi),HS型試塊具有最佳的抗硫酸根離子侵入能力;而GU型水泥制成的試件在硫酸鹽侵蝕環(huán)境中擁有最佳的力學(xué)性能;同時(shí),粗骨料的存在會(huì)阻礙硫酸根離子的傳輸,導(dǎo)致硫酸根離子在骨料前方的聚集;(2)研究建立了混凝土硫酸鹽侵蝕的二維均勻擴(kuò)散-反應(yīng)模型和二維非均勻擴(kuò)散-反應(yīng)模型,并推導(dǎo)了相應(yīng)的有限差分格式。通過(guò)將模型計(jì)算結(jié)構(gòu)與硫酸鹽侵蝕試驗(yàn)數(shù)據(jù)進(jìn)行對(duì)比,驗(yàn)證了模型的合理性與可行性。隨后,基于所提出的混凝土硫酸鹽侵蝕的二維均勻和非均勻模型,分別研究了侵蝕維度、擴(kuò)散系數(shù)、初始鋁酸鈣含量、環(huán)境濃度、化學(xué)反應(yīng)常數(shù)和粗骨料粒徑、投放位置、形狀、含量等對(duì)硫酸鹽侵蝕混凝土結(jié)構(gòu)的影響規(guī)律,研究表明:相較于一維侵蝕,二維侵蝕明顯加劇了混凝土遭受硫酸鹽侵蝕的程度;與均勻模型相比,非均勻模型中考慮了粗骨料對(duì)擴(kuò)散-反應(yīng)過(guò)程的影響,可以更合理地描述混凝土的硫酸鹽侵蝕過(guò)程;在非均勻模型中,粗骨料的粒徑和所處位置可以對(duì)硫酸鹽侵蝕的擴(kuò)散-反應(yīng)行為產(chǎn)生顯著影響;(3)提出了硫酸鹽環(huán)境下混凝土結(jié)構(gòu)耐久性分析方法,建立了硫酸鹽環(huán)境下混凝土結(jié)構(gòu)耐久性分析的極限狀態(tài)方程及相應(yīng)的服役壽命計(jì)算模型,并開(kāi)展了不同硫酸鹽環(huán)境條件和不同材料參數(shù)下混凝土結(jié)構(gòu)的耐久性分析及服役壽命預(yù)測(cè),研究表明,作為混凝土硫酸鹽侵蝕的擴(kuò)散控制和反應(yīng)控制兩個(gè)階段的關(guān)鍵因素,硫酸根離子擴(kuò)散系數(shù)和初始鋁酸鈣含量對(duì)硫酸鹽侵蝕條件下混凝土結(jié)構(gòu)的服役壽命有明顯影響;在合理范圍內(nèi)增加混凝土中的粗骨料含量、提高混凝土結(jié)構(gòu)的保護(hù)層厚度可以延長(zhǎng)其在硫酸鹽侵蝕條件下的服役壽命。
[Abstract]:Sulfate erosion is one of the most important factors that cause damage to the durability of concrete structures. The sulfate ions eroded into the concrete structure can react with the hydrated calcium aluminate and other cement hydration products to produce an expansive material such as calcium vanadite, and the expansion strain and stress exceed the ultimate tensile strength of the concrete structure. The expansive crack is produced and develops continuously with the prolongation of the erosion cycle, which eventually leads to the durability failure of the concrete structure. In this paper, the diffusion reaction behavior of the sulfate corroded concrete is investigated from two aspects of experimental research and numerical simulation, and the corresponding structural durability analysis and service life pre service are carried out. The main contents are as follows: (1) the experimental method of 2-D sulfate erosion was put forward, and the corresponding experimental study on 2-D sulfate erosion was carried out. In the experiment, the sulfate ion intrusion and the stress after the sulfate attack were obtained by carrying out the sulfate concentration test and MTS mechanical test in the concrete after erosion. The composition of the cementitious material, the curing time and the influence of the coarse aggregate on the sulfate erosion are analyzed. The study shows that the HS type specimen has the best anti sulfate ion invasion ability in the 12 week erosion cycle, and the specimens made of GU cement are in sulfur. Acid salt has the best mechanical properties in the environment. At the same time, the existence of coarse aggregate will impede the transmission of sulfate ion and lead to the accumulation of sulfate ion in front of the aggregate. (2) a two-dimensional homogeneous diffusion reaction model and a two-dimensional non-uniform diffusion reaction model are established, and the corresponding finite difference is derived. The reasonableness and feasibility of the model are verified by comparing the model calculation structure with the test data of sulfate attack. Then, based on the proposed two-dimensional and non-uniform model of concrete sulfate erosion, the erosion dimension, diffusion coefficient, initial calcium aluminate content, environmental concentration and chemical reaction constant are studied respectively. The effect of coarse aggregate particle size, placement, shape and content on the structure of sulfate corroded concrete has been studied. The study shows that compared with one dimension erosion, two dimensional erosion obviously aggravates the degree of sulfate erosion of concrete. Compared with the uniform model, the effect of coarse aggregate on the diffusion reaction process is considered in the non-uniform model. The sulphate erosion process of concrete is described reasonably. In the non-uniform model, the particle size and location of coarse aggregate can have a significant influence on the diffusion reaction behavior of sulfate erosion. (3) the durability analysis method of concrete structure under sulphate environment was put forward, and the durability analysis of concrete structures under sulphate environment was established. The limit state equation and the corresponding service life calculation model, and the durability analysis and service life prediction of concrete structures under different sulphate environment conditions and different material parameters are carried out. The study shows that the diffusion coefficient of sulfate radical is the key factor for the two stages of diffusion control and reaction control of concrete sulfate erosion. And the initial calcium aluminate content has an obvious influence on the service life of the concrete structure under the sulphate erosion condition. In a reasonable range, increasing the coarse aggregate content in concrete and improving the thickness of the concrete structure can prolong the service life of the concrete under the sulphate erosion condition.
【學(xué)位授予單位】：廣西大學(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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本文編號(hào)：2050125