| 摘要: |
| 研究了钢纤维体积分数、膨胀剂种类及掺量对不同尺寸的超高性能混凝土(UHPC)试件28d抗压强度及自成型27h后至180d收缩特性的影响.结果表明：以40mm立方体试件抗压强度为基准,不掺膨胀剂时100mm立方体试件的抗压强度换算系数为075~080,而掺有膨胀剂的100mm立方体试件抗压强度换算系数为074~080;UHPC的收缩形式以自收缩为主,约占其总收缩量的870%～927%,掺加钢纤维能够有效降低其收缩量;试验选用的EA1膨胀剂因水化速率过快,在UHPC收缩测试前已基本完全水化,造成试件内部自干燥作用加强,因此增大了UHPC的收缩量;选用的EA2膨胀剂能与空气中的水蒸气及试件内部的水分发生反应并产生持续的膨胀效果,因此在实际应用时应注意控制其掺量，以保证UHPC的体积稳定性. |
| 关键词: 超高性能混凝土 尺寸效应 自收缩 干燥收缩 膨胀剂 |
| DOI：103969/j.issn.1007 9629201904019 |
| 分类号: |
| 基金项目:国家自然科学联合基金资助项目(U1534207);上海市科委项目(17DZ1204206);上海市住房和城乡建设管理委员会项目(2017 2018);上海市政总院科研项目(K2018J024，K2018K001) |
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| Size Effect of Compressive Strength and Shrinkage Characteristics of Ultra High Performance Concrete |
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SHUI Liangliang
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Shanghai Municipal Engineering Design InstituteGroup Co., Ltd., Shanghai 200092, China
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| Abstract: |
| The influence of steel fiber volume fraction, type and content of expansion agent on the size effect of compressive strength and shrinkage characteristic of ultra high performance concrete(UHPC) were studied. The 40mm and 100mm cube compressive strengths of each samples after curing 28d were tested. The shrinkage characteristics of each samples within 180d were also measured and the starting point is 27h after casting. The results show that, if the 40mm cube compressive strength is the control strength, conversion coefficients of 100mm cube compressive strength of UHPC with and without expansion agent are 074080 and 075080, respectively. The autogenous shrinkage of UHPC accounts for 870% to 927% of its free shrinkage, and by adding steel fiber the free shrinkage of UHPC can be reduced effectively. As for EA1, its hydration rate is too fast and a lot of water is consumed during the early hydration stage of UHPC, a severe self desiccation effect will be seen. As a result, UHPC with EA1shows a larger free shrinkage value than UHPC without EA1 As EA2 can react with the water vapor in the air and the water inside the sample and produce a continuous expansion effect, attention should be paid to control its dosage to ensure the volume stability of UHPC in the practical application. |
| Key words: ultra high performance concrete(UHPC) size effect autogenous shrinkage drying shrinkage expansion agent |
