纤维增强水泥基复合材料压剪破坏的细观实验研究

对聚丙烯纤维和钢纤维增强水泥砂浆复合材料和混凝土复合材料进行了MTS 准静态单轴压缩实验和压剪加载条件下的细观力学实验研究。比较两类纤维在这两种加载条件下的作用发现: 在单轴压缩条件下, 钢纤维作用显著, 聚丙烯纤维基本没有什么作用;在压剪加载条件下, 钢纤维在材料各个变形阶段均起明显作用, 聚丙烯纤维在加载过程中起到一定的作用, 但由于含量较少对材料的极限荷载基本没有贡献。在细观实验中, 观察到了钢纤维和碎石颗粒在材料破坏过程中脱粘与断裂的作用方式。但只是在水泥砂浆试件的局部观察到了孔洞崩塌现象, 对于其促成压缩带形成的机理尚须深入的工作。

MESO EXPERIMENTAL INVESTIGATION OF FIBER REINFORCED CEMENTITIOUSCOMPOSITES UNDER COMPRESSION AND SHEAR LOADING

Quasi-static uniaxial compression experiments and meso compression-shear experiments were carried out to investigate the failure properties of polypropylene micro-fiber and steel fiber reinforced cement and concrete composites. Comparing the effects of two kinds of fibers on the composites under these two loading conditions, experimental results show that under quasi-static uniaxial compression, the effects of steel fiber are evident, and those of Polypropylene micro-fiber are not; while under compression and shear loading, steel fiber took on evident effects on the strengthening of the matrix in all of the deformation stages, but polypropylene micro-fiber only reinforced the matrix in the stages before failure and can not improve the ultimate shear strength. The debonding and fracture of steel fiber and gravels in the composites were observed in the meso experiments. However, the void collapse phenomenon was observed only in local of the cement. The mechanism that void collapse will lead to the formation of the compaction band needs to be revealed in further studies.