基于“名义断裂能”的概念研究超高性能水泥基复合材料的断裂特性

Test research on fracture properties of ultra-high performance cementitious composites based on nominal concept of fracture energy

断裂能是描述混凝土等单缝材料断裂破坏特征的重要参数。采用三点弯曲试验方法,通过试验获得超高性能水泥基复合材料基体和超高性能水泥基复合材料的极限挠度值、最大荷载值,绘制超高性能水泥基复合材料基体和超高性能水泥基复合材料的P-δ变化曲线,采用RILEM推荐的断裂功的方法确定超高性能水泥基复合材料基体和超高性能水泥基复合材料的断裂能,并对试件的断裂面进行电镜试验,对试件的破坏进行微观研究。研究表明:PVA纤维的添加,使得P-δ曲线的峰值提高,峰值后的曲线变得平缓,超高性能水泥基复合材料的断裂能较超高性能水泥基复合材料基体提高约6倍。

Fracture energy was an important parameter which could characterize fracture failure characteristics of single slit material just as concrete cracking.Through the testing of three-point bending,the experiment can obtain the maximum load and ultimate deflections of the matrix of ultra-high performance cementitious composites and the experiment also could obtain the maximum load and ultimate deflec- tions of ultra-high performance cementitious composites.Meanwhile, the curve on P-δ of the matrix and ultra-high performance cementi- tious composites appearance was constructed.Fracture energy could be obtained by a method recommended by RILEM.Electron micro- scope scanning and qualitative analysis are given for fracture surface.The result showed that the use of PVA fiber improves the peak of P-δ curve, flexural carrying capacity, ability against crack growth and curves of P-δ after the peak were smoother.The result also showed that Fracture energy of the ultra-high performance cementitious composites increases about 6 times than the matrix.