自密实钢管混凝土的研究与应用

采用自密实混凝土作为钢管核心混凝土．针对钢管混凝土的受力特点和施工工艺．进行自密实混凝土材料的选择和配合比优化。为了确保自密实钢管混凝土的顺利施工和硬化后良好的力学、变形性能，进行了自密实钢管混凝土与普通泵速铜管混凝土拱的现场模拟施工对比试验，以及钢管混凝土短柱的轴心受压对比试验。试验结果表明．自密实混凝土作为钢管核心混凝土，其施工性能明显优于普通泵送混凝土。在施工过程中不泌水、不离析。硬化的混凝土能在各截面上均匀分布；自密实钢管混凝土短柱的组合弹性模量、极限承载力和延性以及后期承载能力方面均与普通泵送混凝土短柱相似。在此基础上．成功地将自密实混凝土应用于莆田市一钢管混凝土拱桥工程，应用结果表明，采用自密实混凝土技术，钢管混凝土拱桥施工顺利、快捷。且更好地保证了工程质量，同时混凝土材料造价与普通泵送混凝土基本持平。

Researching and applying self-compacting concrete filled steel tubes

Self-compacting concrete(SCC)intends to be utilized as the core concrete of concrete filled steel tubes(CFSTs).Based on comprehensive understanding to specific requirements of the CFSTs,mix design optimizations of SCC mixtures are carried out and then SCC mixtures are developed successfully.A series of comparative experiments include a site concrete pumping trial and axial compressive test of SCC and normal concrete(NC) filled steel stub columns are conducted.The results show that the SCC mixtures can be pumped conveniently without any segregation;the mechanical and deformation properties such as the combined elastic modulus,the ultimate bearing capacity of SCC stub columns do not differ significantly from the corresponding properties of NC stub columns with the same strength grade.Finally,an application of SCC in a concrete filled steel tubular arch bridge indicated that employing of SCC is benefit to the homogeneity and quality of the structure,while the total material cost is not increased.