考虑碳化及硫酸盐侵蚀影响的面板混凝土强度特性研究

发布时间：2018-11-07 14:53

【摘要】：研究表明,混凝土面板堆石坝面板混凝土的强度特性受到许多因素的影响,其中碳化和硫酸盐侵蚀为两个主要因素。但工程界目前对于面板混凝土的强度特性研究,仍大多局限于单一因素的影响研究,即使考虑二者的共同作用,也仅按照已有经验粗略判断两者对强度特性的复合影响,而理论依据却明显不足。因此,在考虑碳化与硫酸盐侵蚀共同作用的基础上,深入开展面板混凝土强度特性及其演变规律的研究仍是十分必要的。本文首先对面板混凝土的硫酸盐侵蚀机理及碳化机理进行了系统分析;然后,分别通过硫酸盐干湿循环试验、碳化试验以及碳化与硫酸盐干湿循环的交替试验,分析其对面板混凝土强度特性的影响机理。研究结果表明:(1)水灰比和侵蚀液浓度是面板混凝土抗硫酸盐侵蚀的主要影响方面。水灰比越小,硫酸盐侵蚀后面板混凝土的抗压强度与其劈裂抗拉强度减少幅度越小;侵蚀液浓度越小,硫酸盐侵蚀后面板混凝土的抗压强度与其劈裂抗拉强度减少幅度越小。(2)水灰比与面板混凝土的碳化深度关系密切,水灰比越大,面板混凝土碳化深度越大。随着碳化龄期的延长,面板混凝土碳化深度也逐渐增加。在碳化龄期相同的条件下,碳化深度越大,后续碳化深度的增幅越大。(3)随着碳化时间的延长,面板混凝土的抗压强度与其劈裂抗拉强度也越来越大。水灰比越大,碳化后面板混凝土抗压强度与其劈裂抗拉强度增加幅度越大。随着碳化时间的延长,面板混凝土抗压强度与其劈裂抗拉强度的增加呈现先快后慢的趋势。(4)在碳化与硫酸盐侵蚀交替作用下,水灰比越小,面板混凝土在交替循环下的抗压强度与其劈裂抗拉强度下降幅度越小;侵蚀液浓度越小,面板混凝土在交替循环下的抗压强度与其劈裂抗拉强度下降幅度越小。(5)在碳化与硫酸盐侵蚀共同作用下,二者对面板混凝土强度的影响特征并非各自影响效应的简单叠加,而呈现出交替影响、互为激化的影响规律。
[Abstract]:The results show that the strength characteristics of concrete face slab of concrete face rockfill dam are affected by many factors, among which carbonation and sulfate erosion are two main factors. However, at present, most of the researches on the strength characteristics of slab concrete are still confined to the influence of a single factor. Even if the interaction between the two is considered, the composite effect of the two factors on the strength characteristics can only be roughly judged according to the existing experience. But the theoretical basis is obviously insufficient. Therefore, on the basis of considering the interaction of carbonation and sulfate erosion, it is necessary to deeply study the strength characteristics and evolution law of concrete faced with concrete. In this paper, the mechanism of sulfate erosion and carbonation of concrete face concrete is analyzed systematically. Then, the influence mechanism of sulphate dry and wet cycle test, carbonation test and alternative carbonation and sulphate wet cycle test on the strength characteristics of concrete face concrete was analyzed. The results show that: (1) the water-cement ratio and the concentration of erosive fluid are the main factors affecting the sulfate resistance of concrete face. The smaller the water-cement ratio, the smaller the reduction range of compressive strength and splitting tensile strength of face concrete after sulfate erosion. The smaller the concentration of erosion solution, the smaller the reduction of compressive strength and splitting tensile strength of face concrete after sulphate erosion. (2) the ratio of water to cement is closely related to the carbonation depth of face concrete, and the ratio of water to cement is larger. The greater the carbonation depth of concrete face concrete. With the prolongation of carbonation age, the carbonation depth of concrete face concrete increases gradually. Under the same carbonation age, the greater the carbonation depth, the greater the subsequent carbonization depth. (3) with the prolongation of carbonation time, the compressive strength and the splitting tensile strength of concrete face are also increasing. The higher the water-cement ratio, the greater the increase of compressive strength and splitting tensile strength of carbonized concrete face concrete. With the prolongation of carbonation time, the increase of compressive strength and splitting tensile strength of concrete face concrete shows a tendency of first fast and then slow. (4) under the alternating action of carbonation and sulfate erosion, the ratio of water to cement decreases. The decrease of compressive strength and splitting tensile strength of slab concrete under alternating cycle is smaller. The smaller the concentration of corrosion solution, the smaller the decrease of compressive strength and splitting tensile strength of concrete face concrete under alternating cycle. (5) under the combined action of carbonization and sulfate erosion, The influence characteristics of the two factors on the strength of concrete face slab are not the simple superposition of the effect of each other, but the law of alternating influence and mutual aggravation.
【学位授予单位】：西安理工大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：TV431

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