【作者】 何锦华；

【导师】 钱春香； 缪昌文；

【作者基本信息】 东南大学 ， 材料学， 2006， 硕士

【摘要】 普通混凝土作为混凝土结构的主体材料,被广泛应用于包括建筑工程、交通工程、水利工程、地下工程以及其他特殊结构工程在内的各种土木工程领域。随着现代土木工程日益向着超大规模化和复杂化的方向发展,以及人们对环境的日益重视,使用普通混凝土材料尤其是使用需强力振捣的普通混凝土材料的缺点也日趋明显,限制了混凝土结构在复杂结构物中的应用,城市区域普通混凝土的振捣施工扰民问题也倍受关注。免振捣自密实混凝土具有高流动性、高充填性、高抗离析性等特点,有效解决了浇注振捣困难或无法振捣的难题,为混凝土的应用提供了新的技术保障,具有广阔的市场前景。本文提出了对免振捣自密实高性能混凝土性能的评价方法、性能指标以及相应的试验方法,并根据上述方法对配制的免振捣自密实混凝土拌合物进行试验验证。探讨了混凝土各组成成分对低收缩免振捣自密实高性能混凝土工作性和体积稳定性的影响规律,配制出了C30、C40和C50级低收缩免振捣自密实高性能混凝土,并初步提出了低收缩免振捣自密实高性能混凝土的配合比设计方法和施工控制技术。结果表明,所配制的混凝土不仅在新拌状态,而且在早龄期及硬化后都具有良好的性能。本文主要研究内容和取得的研究结果:1.以自密实工作性为目标的配制技术、试验室评价方法与机理:本文通过正交试验等方法,优化配合比设计,确定了C30、C40、C50自密性免振捣低收缩高性能砼的基础配合比;比较了现行各国对自密实高性能混凝土的试验室评价方法,提出了适合我国国情的自密实高性能混凝土自密实工作性的试验室评价方法。试验结果表明,坍落度、扩展度、倒置坍落度桶流过时间试验方法、L型仪试验方法、U型仪试验方法均适合自密实混凝土工作性的试验室评价。2.以减少干燥收缩为目标的配制优化:本文通过对混凝土组成材料的分析,将外加剂、掺合料、纤维作为对混凝土的变形性能影响最大因素进行系统试验和长龄期测试分析。结果表明,新型聚羧酸混凝土外加剂和减缩剂有效减少了外加剂对混凝土体积收缩的不利影响;30%的粉煤灰、钢纤维和聚丙烯纤维都能够降低自密实高性能混凝土的收缩值,钢纤维和聚丙烯纤维混掺具有叠加效应,对控制自密实高性能混凝土的早期收缩更加有效。3.抗碳化研究与分析:本文根据工程实际应用条件主要研究了自密实高性能混凝土的抗碳化能力。结果表明,优化配制的自密实高性能混凝土有较好的耐久性。4.自密实、低收缩的高性能混凝土配制方法:提出了配制自密实免振捣低收缩高性能混凝土对原材料要求、集料级配设计方法和配合比设计方法。5.自密实混凝土施工工法:根据免振捣自密实混凝土的施工应用经验,提出了自密性免振捣低收缩高性能混凝土的生产控制方法。自密性免振捣低收缩高性能混凝土的工程质量与生产和施工质量密切相关。生产和施工中的各种因素对自密性免振捣低收缩高性能混凝土的质量影响都很敏感,自密性免振捣低收缩高性能混凝土生产和施工的规范化对确保工程质量至关重要。更多还原

【Abstract】 As main material for concrete structure , ordinary concrete has been widely applied in civil engineering including projects related to architecture,transportation, underground, water conservancy and others with special structure. Modern civil engineering moves its way to large scale and complexity, meanwhile, people concern with the environment much more than before. Using ordinary concrete, especially using the one vibrated by strong force, appears many disadvantages, which restricts the application of concrete structure in complex structure.Non-vibratory, self-compacting concrete has good properties of fluidity、fill-in and anti-segregation, which can make moulding vibration easier. It supplies concrete a guatantee for application of new technology and makes a large scale market.The evaluation method of the performance of high-performance self-compacting concrete (HPSCC)with the properties of non-vibration has been put forward in this paper, as well as the performance index and testing method. The HPSCC mixture has been certified.In this paper, the rules that concrete gradients influence the workability and volume change of HPSCC with low shrinkage have been discussed. HPSCC with low shrinkage has been produced by cement grades: C30, C40 and C50. And its mixture ratio design and construction control have been put forward primarily. The results show that this concrete has good performance not only while preparing, but also in early age and rigidification.The main contents of this paper are as follows:1.Operating technique、evaluation method in lab and theoretical analysis at the aim of self-compacting workability.The basic mixture ratio of HPSCC with low shrinkage produced by cement with grade C30、C40 and C50 has been fixed through optimization of mixture ratio by orthogonal experiment. The evaluation methods in the lab of self-compacting concrete belonged to several countries have been compared. Then, we put forward one adapt to our country. As the results show, slump、expansion degree、upset slump barrel、equipment with type L and type U can be applied adapt to evaluation of workability of self-compacting concrete in the lab.2.Operating optimization at the aim of volume stability.Admixture and fiber have been certified as the serious factors that influence the transmutation property of concrete by analyzing concrete gradients. They have been systematically tested in long age. As the results show, new type of polycarboxylic acid-based admixture and shrinkage reducer reduce the negative influences of volume shrinkage. Flyash with a content of 30%, steel fiber and polypropylene fiber reduce the shrinkage of HPSCC. Especially, steel fiber and polypropylene fiber reduce shrinkage in early age of HPSCC as their effect overlapped.3.Durability analysisThe anti-carbonization ability of HPSCC has been investigated. The results show that it has good durability.4.Operating method of HPSCC with stable volume.Material qualification、aggregate gradation design and mixture ratio design of HPSCC with low shrinkage have been brought up.更多还原