高性能混凝土抑制碱骨料反应研究

发布时间：2018-05-27 23:22

本文选题：碱骨料反应 + 岩相法　；参考：《新疆农业大学》2015年硕士论文

【摘要】：混凝土碱骨料反应是影响混凝土耐久性的重要因素之一,本文通过快速砂浆棒法和棱柱体法试验研究了掺合料掺量及水胶比对试件膨胀率的影响及抑制碱骨料反应的能力,得到的主要结论如下:(1)通过岩相法试验确定,乌鲁木齐地区混凝土所用骨料67%为凝灰岩,用快速砂浆棒法和棱柱体法测得膨胀率都超过规范要求,均能判定凝灰岩为碱活性骨料。(2)通过快速砂浆棒法和棱柱体试验研究,抑制碱骨料反应的主要因素是水胶比、掺合料和养护龄期。同龄期混凝土试件的膨胀率,随水胶比降低或掺合料掺量增加而降低,随着养护龄期的延长,混凝土试件的膨胀率逐渐增长。从配合比的角度来看,除了考虑碱含量以外,一方面,通过降低水胶比来增加混凝土的密实度,能降低混凝土中水分的移动和碱离子的移动;另一方面,掺加的矿物掺合料属于活性混合材料,活性成分与水泥熟料的水化产物氢氧化钙和水在有碱的情况下能够发生反应,生成水硬性物质。掺合料之所以能够抑制碱骨料反应,就是因为其吸收了水泥或者混凝土中的碱,降低了混凝土中的碱含量,可以有效地起到抑制碱骨料反应的作用。其次,掺合料可以等量去取代水泥,水泥用量少了,混凝土中的碱含量也会相应地减低,也就等于降低了混凝土中的碱。(3)通过试验研究发现一种现象,掺加掺和料的棱柱体法试件52周龄期内膨胀率受水胶比影响较小,0.44水胶比试件膨胀率低于低水胶比试件的膨胀率。按照高性能混凝土强度规律分析,0.44水胶比的试件密实度远低于0.40以下水胶比的试件,试件内部的孔隙率远大于、多余低水胶比试件。因此,这种现象可能是应大水胶比试件中的孔隙抵消了部分骨料界面发生碱骨料膨胀的应力,才造成0.44水胶比试件未有明显的膨胀率增长,望在以后研究中能得到进一步的验证。
[Abstract]:The alkali aggregate reaction of concrete is one of the important factors affecting the durability of concrete. In this paper, the influence of admixture content and water / binder ratio on the expansion rate of the specimen and the ability to restrain the reaction of alkali aggregate are studied by means of rapid mortar bar method and prism method. The main conclusions are as follows: (1) through lithofacies test, 67% of aggregate used in Urumqi concrete is tuff, and the expansion rate measured by rapid mortar bar method and prism method is above the standard requirement. Through rapid mortar bar method and prism test, the main factors of inhibiting alkali aggregate reaction are water-binder ratio, admixture and curing age. The expansion rate of concrete specimens at the same age decreases with the decrease of water-binder ratio or with the increase of admixture content. With the extension of curing age, the expansion rate of concrete specimens increases gradually. From the point of view of mix ratio, besides considering the alkali content, on the one hand, by reducing the water-binder ratio to increase the compactness of concrete, the movement of water and alkali ions in concrete can be reduced; on the other hand, The mineral admixture is a kind of active mixing material. The active component can react with the hydration product of cement clinker calcium hydroxide and water in the presence of alkali to form a hydrated substance. The reason why admixture can inhibit alkali aggregate reaction is that it absorbs alkali in cement or concrete, reduces alkali content in concrete, and can effectively inhibit alkali aggregate reaction. Secondly, the admixture can replace cement by the same amount. When the amount of cement is reduced, the alkali content in concrete will be reduced accordingly, which is equivalent to reducing the alkali content in concrete. The swelling ratio of prism specimen with admixture was less affected by water-binder ratio in 52 weeks than that of low water-gel ratio. According to the strength law of high performance concrete, the compactness of the specimen with 0.44 water-binder ratio is far lower than that of the water-binder ratio below 0.40, and the internal porosity of the specimen is much larger than that of the low water-binder ratio. Therefore, this phenomenon may be due to the fact that the pores in the water / binder ratio specimens offset the stress of alkali aggregate expansion at the interface of some aggregates, resulting in no obvious increase in the expansion rate of 0.44 water-gel ratio specimens. It is hoped that further verification will be made in future studies.
【学位授予单位】：新疆农业大学
【学位级别】：硕士
【学位授予年份】：2015
【分类号】：TU528

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