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南京五桥钢壳微膨胀混凝土配制技术及变形性能研究
作者：徐文冰1，2，3，叶仙松1，2，3，张思1，2，3，李演1，2，3
（1.中交武汉港湾工程设计研究院有限公司，湖北 武汉 430040；
2.长大桥梁建设施工技术交通行业重点实验室，湖北 武汉 430040；
2.长大桥梁建设施工技术交通行业重点实验室，湖北 武汉 430040；
3.海工结构新材料及维护加固技术湖北省重点实验室，湖北 武汉 430040）
摘要：在初步确定胶材用量、水胶比、砂率、碎石级配等参数的基础上，通过调整掺合料及膨胀剂掺量，优选出最佳配比，并在最佳配合比的基础上，进一步研究膨胀剂掺量对混凝土变形性能的影响。结果表明：当膨胀剂掺量为4%时，混凝土自身的化学减缩和干燥收缩与膨胀剂产生的膨胀作用相当，钢壳混凝土才具有补偿收缩和微膨胀效应；当膨胀剂掺量过高（大于8%）时，混凝土强度明显降低。以硫铝酸盐、硫酸盐及氧化钙复合为主的膨胀剂其膨胀势主要来源于水化后产生了针棒状的钙矾石和定向排列的氢氧化钙晶体，其水化产物能可以填充混凝土内部因水化引起的孔隙，能一定程度地改善混凝土内部的孔隙结构。
关键词：膨胀剂；钢壳混凝土；配合比；变形性能；孔结构分析
中图分类号：TU528.55 文献标识码：A 文章编号：1001-702X（2019）10-0141-05
Study on preparation technology and deformation properties of concrete filled steel tube of the fifth bridge of Nanjing
XU Wenbing1，2，3，YE Xiansong1，2，3，ZHANG Si1，2，3，LI Yan1，2，3
（1.CCCC Wuhan Habour Engineering Design & Research Co.，Ltd.，Wuhan 430040，China；
2.Key Laboratory of Large-span Bridge Construction Technology，Wuhan 430040，China；
3.Hubei Key Laboratory of Advanced Materials ＆ Reinforcement Technology Research for Marine Environment Structures，Wuhan 430040，China）
3.Hubei Key Laboratory of Advanced Materials ＆ Reinforcement Technology Research for Marine Environment Structures，Wuhan 430040，China）
Abstract：The optimum ratio in this paper was selected by adjusting the dosages of the mineral admixture and the expansive agent，based on the preliminary determination of the parameters including amount of cementitious material，water-binder ratio，sand ratio and gravel grading. And the influence of the content of expansive agent on the deformation performance of concrete was further studied. Experimental results show that when the content of expansive agent is 4%，the chemical shrinkage and drying shrinkage of concrete are equivalent to the expansion caused by expansion agent，steel shell concrete has compensating shrinkage and micro-expansion effect. When the content of expansion agent is too high（more than 8%），concrete strength decreases obviously. The expansion potential of the expansive agent，mainly composed of sulphoaluminate，sulfate and calcium oxide，mainly comes from the acicular calcite and directional calcium hydroxide crystals produced after hydration. The hydration products can fill the pores caused by hydration inside the concrete and improve the pore structure inside the concrete to a certain extent.
Key words：expansion agent，concrete filled steel tube，mix proportion，deformation performance，pore structure analysis