鉴于含粗骨料的超高性能混凝土UHPC(CA)的抗火性特征亟待研究探明,文中对国内外UHPC(CA)的发展历程与火灾高温性能研究进行了综述.提出应针对C100--C150范围内的UHPC(CA)开展高温损伤与抗火性研究.UHPC(CA)抗火性改善的主要目标首先是抑制作为主要损伤模式的高温爆裂,其次是减小高温引起的裂纹扩展、化学分解、孔粗化等其他损伤,使UHPC(CA)具有良好的火灾安全性.而抑制高温爆裂最有效的手段是抑制混凝土内部主要由蒸汽压所驱动的裂纹扩展.基于高温造成的UHPC(CA)宏观断裂性能与微观结构劣化等损伤特征,建立UHPC(CA)抗火性改善机理,提出确保UHPC(CA)具有良好抗火性的技术途径.定量确定聚合物纤维、钢纤维或其他种类的纤维分别对抗火性的贡献以及这几种纤维的相互作用,确定混杂纤维中聚合物纤维、钢纤维或其他种类纤维的合理用量范围.
Since it is urgently needed to identify the characteristics of fire resistance of ultra-high-performance concrete with coarse aggregate ( UHPC (CA) ), properties and performance of UHPC (CA) subjected to fire or high temperatures are summarized in this paper based on a literature review of both national and international development of UHPC (CA) and high temperature properties of it. It is concluded that investigations should be carried out on U HPC(CA) with the strength grade between C100 and C150. Thermally explo- sive spalling will be tested as a main research objective and the other damages should also be minimized, including crack growth, chemical decomposion, and pore structure coarsening, in order to make UHPC(CA) possess satisfactory fire safety. The efficient ap- proach for prohibiting explosive spalling should be control internal crack propogation in concrete driven mainly by vapor pressure. The macro-scale properties and performance will be associated with the feature of microstructure of UHPC (CA) in order to establish the mechanism for improving fire resistance of UHPC(CA) and hence to propose technical measures to ensure good fire resistance of UHPC (CA). The influences of polymer fiber, steel fiber and other sorts of fibers on fire resistance of UHPC(CA) should be quantitatively evaluated, and the interaction between them should also be identified, so as to propose optimun dasoges of these fibers when hybrid fiber will be employed in UHPC (CA).