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自密实高性能混凝土在建筑结构方面的研究与应用
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摘要
自密实混凝土属于高性能混凝土,它具有高流动性、高抗离析性、高填充性的性能,在自重作用下无需振捣,自行填充模板空间,形成自密实的混凝土结构,有良好的力学性能和耐久性能,可以加快工程建设进度、缩短工期、有效控制混凝土的质量、提高建筑物及构筑物的耐久性,并有利于环境保护,具有较高的社会和经济效益。
     国内自密实高性能混凝土的研究与应用还处于起步阶段,而且这种高性能混凝土的性能随各地区材料的不同其差异较大。本文旨在通过在青岛地区材料基础上的自密实高性能混凝土的试验研究应用,得出自密实高性能混凝土的工作性能和力学性能规律,研制出常用强度等级的免振捣高性能自密实高性能混凝土,促进自密实高性能混凝土在我国的推广应用。
     为得到自密实高性能混凝土的最佳工作性能,在研究中借助流变学理论,分析研究了混凝土拌合物免振捣成型和密实的机理,在大流动性的前提下,要求混凝土具有良好的填充性、钢筋间隙通过性和粘聚性,防止泌水、离析,解决变形能力与抗离析性能力的矛盾。通过加工的March筒、截锥形圆模、U型仪、L型混凝土流动仪等实验仪器以及对各种原材料的物理及化学性能展开详尽的调查研究,进行了多种材料下的水泥与外加剂相容性、混凝土的流动性、混凝土的填充性和钢筋通过性、混凝土的抗离析性等系统试验,在对34组试验、500多个数据的详细认真分析的基础上,利用复合后的外加剂,得出各项工作性能均较佳的自密实混凝土所用原材料比例范围。
     在满足自密实高性能混凝土工作性能的前提下,通过强度试验得出常用强度等级混凝土的配合比,检测该配合比下的自密实高性能混凝土的抗压强度、劈裂抗拉强度、弹性模量、钢筋握裹力性能、抗渗性、收缩性、抗炭化性等性能,以及各种性能与普通混凝土的比较,验证自密实高性能混凝土硬化后的各方面力学性能是完全能够符合要求的,并且具有较高的耐久性。
     试验研究后,在高层住宅楼的剪力墙板中进行了实践应用,经检测,试验数据完全正常,达到了预期目的和要求,较为成功。
     根据工程应用后结果,利用本文所提出的自密实高性能混凝土的工作性能标准和混凝土设计方法是可行的,具有使用的适用性和可靠性,为该种混凝土在更广阔的领域的进一步发展奠定了基础。
Self-densifying high performance concrete is well-performing concrete with the good performance of fluidity, anti-segregation and filling-up-space. With its own gravity and without any vibration, it can automatically fill up the space in and between fixed shutters and form self-densified concrete structure of ideal dynamic property and durability, therefore, it can accelerate construction progress of a building, shorten the construction period, secure concrete quality and improve the building's durability. In the mean time, it is conducive as well for environment protection and effects remarkable social and economic efficiency.
    The research and practical application of the self-densifying high performance concrete in China is still at the initial stage, and property of the said concrete verifies a lot due to difference of material from various regions. Basing on test, research and practical application of the said concrete in this region, this essay is aimed at concluding the regularity of its working performance and dynamic property, developing its products of grades most in use, and promoting its popularization and practical application in our country.
    To best achieve the working performance of the said concrete, with the help of theology theory in the research, we have analyzed the principle of free-vibration densifying and shaping of mixed concrete, that is, with the perquisite of fluidity, the concrete should have good property of filling-up-space, penetration through voids of fixed steel reinforcement, adherence and prevention from losing water and segregation, and the conflict between anti-segregation and deforming capability should be sorted out. Using processed March cylinder, tapered circular mould, U-shaped instrument, L-shaped concrete fluidity instrument and some other testing instruments, and after research and study to physical and chemical property of various raw material. Systematic tests have been carried out in respect of consistency between cement and additive, concrete fluidity, concrete filling-up-space and penetration capability and concrete anti-segregation property, basing on prudent and careful analysis to results of 34-time tests a
    nd more than 500 data, and with utilization of combined additive, we finally conclude the proper mix design range for the self-densifying high performance concrete with ideal working performance at all respects.
    
    
    With the prerequisite of meeting requirement of its working performance, the mix design of common grades can be concluded though strength test if we check various property of the said concrete with the certain mix design, such as compressive strength, tensile strength, elastic modulus, reinforcement wrapping strength, leakage resistance, shrink property and charring resistance, and compare them with property of ordinary concrete, we will find that the various dynamic property of self-densifying high performance concrete is very satisfactory and the durability is quite ideal.
    After library researches and test, we have applied the new material to shear wall of a multi-story residential building, and inspection and test results have proved the success.
    Being tested by practical application, the working performance standard and mix design methodology for the self-densifying high performance concrete as above stated are feasible, practical and reliable, therefore it lays the foundation for further development of the said concrete in wide realm.
引文
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