减缩防裂高性能混凝土外加剂的试验研究

发布时间：2018-07-11 15:10

本文选题：减缩剂 + 收缩　；参考：《北京交通大学》2013年硕士论文

【摘要】：各种混凝土外加剂在工程中发挥着越来越重要的作用。在实际工程施工及使用的过程中发现,掺加减水剂混凝土的收缩、裂缝问题比普通混凝土更加凸显。掺减水剂会使得混凝土早期自收缩和干燥收缩增大,并且使收缩的时间提前。研究表明,采用掺减缩剂的方法在降低收缩率、减小裂缝的同时能够保持混凝土力学性能,改善拌合物性能和耐久性。本文通过对三种减缩剂分别进行干缩试验,得到一种减缩效果明显、力学性能改善显著的减缩高性能混凝土外加剂,之后研究该复合外加剂对混凝土抗裂性能、新拌性能及耐久性的影响。主要成果和结论如下： 1、通过对现有干燥收缩测量仪器的比较和分析,提出一种立杆式收缩测量方法,这种方法不仅精度高,而且适用于长期收缩的测量。 2、在保持坍落度相同的条件下,对不同掺量的减缩剂A、B进行水泥胶砂干燥收缩试验,结合力学性能试验结果,得到减缩剂B减缩率高于减缩剂A的结论。 3、相同条件下,对不同掺量的减缩剂B、D进行混凝土干燥收缩和力学性能试验,结果表明,掺量为1%的减缩剂B减缩效果最明显,且力学性能较好。 4、对不同规范提出的圆环开裂试模进行比较分析,得到适用于不同骨料粒径的圆环试模尺寸。 5、在圆环开裂试验中,掺加复合型减缩外加剂的胶砂圆环试件没有产生开裂,说明该复合外加剂抗裂效果良好。 6、对比减缩率、力学性能及抗裂试验结果,相同种类和掺量的减缩防裂高性能外加剂效果呈现一致性。 7、减缩防裂型高性能外加剂既能配成早强型混凝土又能配成缓凝型混凝土,以适应不同工程的实际需要。 8、减缩防裂型高性能外加剂改善了混凝土内部孔结构和孔径分布,因此能有效提高混凝土的抗氯离子渗透性能和力学性能。
[Abstract]:All kinds of concrete admixtures play a more and more important role in engineering. In the course of practical construction and application, it is found that the shrinkage and crack problem of concrete with water reducing agent is more prominent than that of ordinary concrete. The addition of water reducing agent increases the early self-shrinkage and drying shrinkage of concrete and advances the shrinkage time. The results show that the shrinkage rate and crack can be reduced by adding shrinkage reducing agent, while the mechanical properties of concrete can be maintained, and the performance and durability of the mixture can be improved. In this paper, through dry shrinkage test of three kinds of shrinkage reducing agents, a shrinkage reducing high performance concrete admixture with obvious shrinkage reduction effect and significant improvement in mechanical properties is obtained, and then the anti-cracking performance of the composite admixture to concrete is studied. Effects of fresh mix performance and durability. The main results and conclusions are as follows: 1. Through the comparison and analysis of the existing dry shrinkage measuring instruments, a vertical rod shrinkage measurement method is proposed, which not only has high precision, And it is suitable for the measurement of long-term shrinkage. 2. Under the condition of keeping the same slump, the dry shrinkage test of cement sand with different content of shrinkage reducer AZB is carried out, and the results of mechanical properties test are combined. The conclusion that the shrinkage rate of reducing agent B is higher than that of reducing agent A is obtained. 3. Under the same conditions, the dry shrinkage and mechanical properties of concrete with different content of shrinkage reducer BfD are tested, the results show that, The shrinkage reduction effect of 1% reducer B is the most obvious, and the mechanical properties are better. 4. The size of ring test die suitable for different aggregate particle size was obtained. 5. In the ring cracking test, no cracking was found in the cemented sand ring specimen with compound reducing admixture. The results show that the anti-cracking effect of the compound admixture is good. 6. The results of shrinkage reduction, mechanical properties and crack resistance test are compared. The effect of the same kind and amount of anti-shrinkage and anti-crack high performance admixture is consistent. 7. The shrinkage and anti-crack type high performance admixture can be used to make both early-strength concrete and retarded concrete. In order to meet the practical needs of different projects. 8, the anti-shrinkage and anti-cracking high performance admixture can improve the pore structure and pore size distribution of concrete, so it can effectively improve the chloride ion permeability and mechanical properties of concrete.
【学位授予单位】：北京交通大学
【学位级别】：硕士
【学位授予年份】：2013
【分类号】：TU528.042

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