高性能混凝土高温爆裂研究进展

Progress of Study on Explosive Spalling of High Performance Concrete at Elevated Temperatures

基于高性能混凝土应用的广泛性和遭遇火灾的危害性,对国内外关于高性能混凝土在高温或火灾下发生爆裂的研究进行分类总结。高性能混凝土爆裂研究的梳理工作围绕爆裂机理、爆裂影响因素、爆裂抑制3个方面来展开。结果表明:当前爆裂机理学说还不能全面揭示高性能混凝土爆裂发生的原因,但是存在的共同点是蒸汽压力和热应力与混凝土抗拉强度的相互作用;高性能混凝土爆裂的影响因素众多,有必要对基本因素的孔压力计算方法开展进一步研究;高性能混凝土爆裂的预防措施众多且有效,单掺聚丙烯纤维、钢纤维的掺量可参照相关表达式进行预测,二者混杂时掺量间的关系还未见报道,经过综合对比分析,推荐在高性能混凝土中掺入聚丙烯纤维;针对新建、既有的高性能混凝土结构以及超高性能混凝土,建议开展爆裂设计,从源头上实现爆裂抑制;对于掺入外加物的高性能混凝土结构,还需要进行火灾中与火灾后的力学性能研究,而对于采取外涂或外贴方式抑制爆裂的结构则需要进行拆装施工工艺与规范化的研究。

Based on the extensive use of high performance concrete(HPC)and the danger of fire,researches on HPC explosive spalling at elevated temperatures or fire were classified and summarized,both at home and abroad.The sorting of HPC explosive spalling was focused on three aspects:mechanism,influence factor,inhibition.The results show that the current theories cannot fully explain HPC explosive spalling under elevated temperature or fire,but there is a common point that the explosive spalling is the interaction of thermal pressure and vapor stress and tensile strength of concrete.Many factors can induce the explosive spalling,therefore,it is necessary to continue a further study on the method of calculating the pore pressure as the basic factor.Inhibition measures for explosive spalling are numerous and effective.As a single addition to HPC,the amount of polypropylene fiber(PPF)or steel fiber can be predicted differently by regression expressions.The relationship of the hybrid ratio is not reported when PPF and SF are mixed,and the PPF is the recommended addition to the high strength concrete after comprehensive comparison and analysis.Aiming to the new,existing high performance concrete structure and the ultra-high performance concrete,the design of explosive spalling is introduced to represent inhibition measures for the explosive spalling,which will be beneficial to bring about the inhibition effect in the initial stage of building design.For the high performance concrete structures with admixture for inhibition for explosive spalling,it is suggested that the further work should focus on mechanical behaviors of the structure under or after fire.But to the structure with external coating or posting measures for inhibition for explosive spalling,it is necessary to get further study and improve on the assembled and disassembled techniques and standardization constructions.