【作者】 史长城；

【导师】 赵顺波；

【作者基本信息】 华北水利水电学院 ， Structure Engineering， 2007， 硕士

【摘要】 混凝土耐久性研究是当今混凝土结构研究中的一个重要组成部分,而混凝土碳化与硫酸盐腐蚀均是混凝土耐久性研究的重要组成部分。碳化破坏混凝土的碱性环境,导致钢筋锈蚀,混凝土结构失效。硫酸盐腐蚀是一种化学腐蚀,它的主要产物为钙矾石、石膏以及近年来新发现一种腐蚀产物——碳硫硅钙石(TSA),前两种产物主要是导致混凝土开裂失效,后一种产物主要是破坏混凝土中的水化硅酸钙(C-S-H),使混凝土软化破坏。目前,对混凝土碳化的研究比较深刻全面,但是对混凝土部分碳化区的研究还不够深入。对混凝土硫酸盐腐蚀的研究也取得了不少成果,但是对硫酸根的扩散过程还缺乏的定量的分析,对各种产物的形成机理与条件的认识还不够明确。另外,以往的研究多是仅仅研究混凝土碳化或硫酸盐腐蚀,很少有人进行混凝土碳化与硫酸盐腐蚀共同作用下的研究,基于此本文主要做了以下几个方面的工作并取得系列成果:1:对同一试件分别使用彩虹指示剂与酚酞试剂两种试剂测量碳化深度,对比研究了不同水灰比不同湿度以及不同碳化龄期两种试剂测量的混凝土碳化深度的变化规律,最后,通过热重分析试验对两种试剂的测试结果进行验证。彩虹指示剂的测试结果显示混凝土部分碳化区很短,热重分析的结果与彩虹指示剂的测试结果相吻合。酚酞试剂测试的碳化深度偏小,水灰比越小,偏差越大。2:分别采用BP神经网络与RBF神经网络分内推与外推两种形式对彩虹指示剂的测试结果进行了分析与预测。发现BP网络的外推效果较好,而RBF网络的内推效果更优。3:分三种工况研究了四种浓度的腐蚀溶液(硫酸根浓度分别为:0,850mg/l,35000mg/l,73000mg/l)中混凝土碳化与硫酸盐腐蚀共同作用下混凝土的劣化机理,三种工况分别是硫酸盐单独腐蚀、先碳化再硫酸盐腐蚀以及碳化与硫酸盐腐蚀交替。测试的指标包括混凝土抗压强度、劈裂抗拉强度、质量变化以及不同腐蚀龄期混凝土中的硫酸根含量及相应的热重分析试验。经过一年的腐蚀发现,三种工况下的抗压、抗拉强度均远未达到破坏,也未出现明显的质量损失。硫酸根含量与热重分析的结果表明:硫酸盐单独腐蚀工况硫酸根的侵蚀深度较小,但硫酸根含量较大,除最大浓度溶液中试件首层的主要产物为石膏外,其余的主要腐蚀产物为钙矾石;先碳化再硫酸盐腐蚀工况硫酸根的腐蚀深度较大,但硫酸根含量较小,表层已碳化区的混凝土中硫酸根主要以游离态存在,到了腐蚀后期有碳硫硅钙石(TSA)生成,内部未碳化区的主要腐蚀产物为钙矾石;碳化与硫酸盐腐蚀交替工况,表层混凝土中的硫酸盐侵蚀产物有一个先形成后来又因碳化而分解的过程,其腐蚀过程较前两个工况更为复杂。更多还原

【Abstract】 At present, the research of concrete durability is an important part of the research of concrete structures; both concrete carbonization and sulfate corrosion are important parts of the concrete durability. The alkaline circumstance of concrete is destroyed by carbonization, resulting in reinforce steel rusting and concrete structure lapsing up. Sulfate corrosion is a type of chemical corrosion, its mine products are ettringite(AFt),gypsum and thaumasite(TSA) which is a new discovering product, the front two kinds of product result in concrete structures crazing and lapsing up, and the mine function of thaumasite is to destroy C-S-H of concrete and to soften concrete. Now, the research to concrete carbonization is very profoundly and completely, but the research to half-carbonized zone isn’t enough. The research to sulfate corrosion has gotten lots of fruit, but it shorts of quantitative analysis to sulfate radical ion diffusion and it isn’t certain of mechanism of kinds of products’forming process and condition. In addition, the most front research is only on concrete carbonization or sulfate corrosion, but the research of concrete carbonization and sulfate corrosion combined action is very few to be done, Based on previous work, this paper has mainly done the following several tasks and made serial achievements:1: Both rainbow indicator and phenolphthalein indicator are used to test carbonation depth for all the same samples, three kinds of factors which are water to cement ratio relative humidity and carbonized age are considered, the comparison research of carbonation depth tested by the two indicators is done, at last, the result tested by the two indicators is demonstrated through the experimentation of thermal gravity analysis. The result tested by rainbow indicator indicates that the half-carbonized zone is very short, and the depth tested by rainbow indicator is uniform with the result of thermal gravity analysis. The carbonation depth tested by phenolphthalein indicator is shorter, and the difference is bigger with the decreasing of water to cement ration.2: The analysis and forecast were carried out for the carbonation depth tested by rainbow indicator by BP network and RBF network with the models of inside forecast and outside forecast. We find the effect of BP network’s outside forecast is better, and RBF network’s inside forecast is better.3: In this experimentation three solutions which are separate corrosion, corrosion after carbonating some depth and carbonation and corrosion alternate action under four kinds of sulfate liquor (the four kinds of liquor’s sulfate radical ion density are 0, 850mg/l, 35000mg/l, 73000mg/l) are consider, the concrete’s deteriorate mechanism of the three solutions is been researched. The targets tested in this experimentation are concrete samples’compressive and splitting-tensile strength, change of mass, sulfate radical ion content under the different corrosion age and its thermal gravity analysis. After one year corrosion, compressive strength and splitting-tensile strength don’t reach to destroy under three kinds of solution, and the obvious mass lose doesn’t appear. The result of sulfate radical ion content and thermal gravity analysis indicate: corrosion depth of sulfate radical ion under solution of separate corrosion is smaller than under solution of corrosion after carbonating some depth, but sulfate radical ion content is bigger, besides the 1st layer of samples’main product are gypsum under the biggest density liquor, the other’s main product is ettringite; Corrosive depth of sulfate radical ion under the solution of corrosion after carbonating some depth is bigger, but sulfate radical ion content is smaller, sulfate radical ion is presence as free form in the front layers concrete which have carbonated, thaumasite appears until late stage corrosion, and the mine product is ettringite in the inside concrete which doesn’t been carbonate; Under the solution of carbonation and sulfate corrosion alternate action, the sulfate corrosion products of surface layer concrete have a process which decompose for carbonation after form, and the process is more complex than the front two solutions.更多还原