养护制度对超高性能混凝土抗高温爆裂性能的影响  

Influence of Curing Regime on Resistance of Ultra-High Performance Concrete to Explosive Spalling Under High Temperature

作　　者：牛旭婧 乜颖 朋改非[2] 尚亚杰 丁宏 曲维峰 NIU Xujing;NIE Ying;PENG Gaifei;SHANG Yajie;DING Hong;QU Weifeng(State Key Laboratory of Hydroscience and Engineering,Tsinghua University,Beijing 100084,China;Faculty of Civil Engineering,Beijing Jiaotong University,Beijing 100044,China;Beijing Uni-Construction Group Co.,Ltd.,Beijing 100061,China;Beijing New Aerotropolis Holdings Co.,Ltd.,Beijing 102602,China;Beijing Construction Engineering Group(BCEG),Hengjun Engineering Detection Co.,Ltd.,Beijing 102612,China)

机构地区：[1]清华大学水沙科学与水利水电工程国家重点实验室,北京100084 [2]北京交通大学土木建筑工程学院,北京100044 [3]北京住总集团有限责任公司,北京100061 [4]北京新航城控股有限公司,北京102602 [5]北京建工恒均工程检测有限公司,北京102612

出　　处：《硅酸盐学报》2020年第8期1212-1222,共11页Journal of The Chinese Ceramic Society

基　　金：国家自然科学基金(51878032,51278048);北京市自然科学基金(8172036)。

摘　　要：采用4种不同养护制度(20℃水养、热水养护、干热养护和热水-干热组合养护)制备超高性能混凝土(UHPC),测定其高温爆裂行为,并结合多种微观测试技术,对UHPC的微观结构进行分析。结果表明:组合养护能够明显改善UHPC的抗高温爆裂性能,且当先进行90℃热水预养护2 d,再进行250℃干热养护3 d时,混凝土的高温爆裂现象完全被抑制。明显不同于通常的掺加聚丙烯纤维抑制爆裂的是,热水-干热组合养护是一种新的抑制爆裂方法。其机理是内部游离水的减量化机理,即:组合养护可使UHPC内部建立一种高温蒸汽环境,有效促进水泥水化、激活掺合料的火山灰活性,导致许多致密的水化产物得以生成,同时消耗大量混凝土内部游离水,使得制备出的UHPC在高温加热过程中所能形成的蒸汽压较低,不足以引发高温爆裂。Explosive spalling behavior and microstructure of ultra-high performance concrete(UHPC) prepared with four different curing regimes(i.e., 20 ℃ water curing, hot water curing, dry air heating and hot water-dry air combined curing) were investigated. The results indicate that the combined curing is efficient to enhance resistance of UHPC to explosive spalling under high temperature. No spalling occurs on the UHPC cured by 90 ℃ hot water curing for 2 d and 250 ℃ dry air heating for 3 d. Such a combined curing is a novel approach to prevent explosive spalling of UHPC at elevated temperature, which is different from adding polypropylene fiber usually employed. It can be attributed to an internal free water minimizing mechanism. During dry air heating within the combined curing, a high-temperature steam environment can be established inside UHPC. Thus, further hydration of residual cement and pozzolanic reaction of mineral admixtures both can be activated to form massive dense hydrates. Meanwhile, most of internal free water has been consumed, so that the vapor pressure inside UHPC under high temperature is decreased, hence prohibiting the spalling occurrence efficiently.

关 键 词：超高性能混凝土 组合养护 高温爆裂 微观结构 游离水 

分 类 号：TU528[建筑科学—建筑技术科学]