含铝物质对混凝土中碱—硅酸反应抑制作用的研究

发布时间：2018-05-03 01:36

本文选题：碱-硅酸反应 + 混凝土　；参考：《河北联合大学》2014年硕士论文

【摘要】：混凝土中的碱-硅酸反应是导致混凝土结构破坏的主要原因之一，其反应过程缓慢，影响因素复杂，，难以预测和修复。因此，研究碱-硅酸反应的抑制措施是研究混凝土耐久性的一项重要内容。课题研究了不同含铝物质对混凝土中碱-硅酸反应的抑制效果，并探讨了含铝物质抑制碱-硅酸反应的机理。参照ASTM C1293-08b，采用混凝土棱柱体试验法，以膨胀率作为比较对象，研究了Al(OH)3和Al2O3对混凝土中碱-硅酸反应的长期抑制效果，并结合混凝土试块的强度试验，得出含铝物质对混凝土强度的影响规律。试验结果表明：内掺30%Al(OH)3在短期内会降低混凝土强度，但是可以长期有效地抑制混凝土中的碱-硅酸反应膨胀；Al2O3对碱-硅酸反应的抑制不具有长期有效性。采用碱溶液浸泡法，通过对试样在不同龄期内的XRD分析，研究含铝物质对碱-硅酸反应产物组成的影响。试验结果表明：Al(OH)3的掺入可以明显改变体系中产物的矿物组成，使体系中生成Al2Si2O3(OH)4和CaAl2SiO8等铝硅酸盐矿物，消耗了活性SiO2，从而抑制了碱-硅酸反应膨胀。采用水泥浆体法，通过对比和分析不同龄期内水泥浆体与活性玻璃界面处的SEM图像和EDS图谱，研究了含铝物质对碱-硅酸反应产物形貌和组成的影响。试验结果表明：内掺30%Al(OH)3可以明显改变水泥浆体与活性骨料界面处产物的形貌和组成。一方面，Al3+取代C-S-H凝胶中的Si4+，使凝胶带负电荷；另一方面，Al3+在活性骨料界面处形成具有纤维网状的沸石类铝硅酸盐矿物，两种作用都会显著降低混凝土体系中有害碱的数量，从而有效地抑制混凝土中的碱-硅酸反应。
[Abstract]:The alkali-silicic acid reaction in concrete is one of the main reasons leading to the destruction of concrete structure. The reaction process is slow and the influence factors are complex, so it is difficult to predict and repair. Therefore, it is an important content to study the durability of concrete by studying the inhibition measures of alkali-silicic acid reaction. In this paper, the inhibition effect of different aluminum-containing materials on the alkali-silicic acid reaction in concrete was studied, and the mechanism of the inhibition of alkali-silicic acid reaction by the aluminum-containing material was discussed. Referring to ASTM C1293-08b, the long-term inhibition effect of Al(OH)3 and Al2O3 on alkali-silicic acid reaction in concrete was studied by means of concrete prism test method and the expansion rate was taken as the comparison object, and combined with the strength test of concrete test block. The effect of aluminum on the strength of concrete is obtained. The experimental results show that the strength of concrete can be reduced by adding 30%Al(OH)3 in the short term, but it is not effective for a long time to suppress the expansion of alkali-silicic acid reaction and Al _ 2O _ 3 in concrete. The effect of aluminum on the composition of alkali-silicic acid reaction products was studied by XRD analysis of samples in different ages by soaking in alkali solution. The experimental results show that the addition of w / Al _ 2O _ 3 can obviously change the mineral composition of the product in the system and make the aluminosilicate minerals such as Al2Si2O3(OH)4 and CaAl2SiO8 in the system consume active Sio _ 2 and thus inhibit the expansion of alkali-silicic acid reaction. By comparing and analyzing the SEM images and EDS diagrams of the interface between cement paste and active glass at different ages, the effect of aluminum on the morphology and composition of the products of alkali-silicic acid reaction was studied by using cement paste method. The experimental results show that the morphology and composition of the products at the interface between cement paste and active aggregate can be changed obviously by adding 30%Al(OH)3. On the one hand, Al3 replaces Si4 in C-S-H gel, which makes the gel negatively charged; on the other hand, Al3 forms fibrous reticulate aluminosilicate minerals at the interface of active aggregate, both of which can significantly reduce the amount of harmful alkali in concrete system. Thus the alkali-silicic acid reaction in concrete is effectively suppressed.
【学位授予单位】：河北联合大学
【学位级别】：硕士
【学位授予年份】：2014
【分类号】：TU528

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