中文摘要：

采用反射式焦散线方法对水泥石中添加玻璃纤维后的强度变化问题进行了实验研究。首先，制作了不添加与添加玻璃纤维的2种水泥石试件，并采用镜面移植方法在试件的表面进行反射镜面的制作与加工。然后，采用多火花式高速摄影系统对试件在冲击断裂过程中的裂纹扩展和裂纹尖端焦散线的情景进行记录。最后，对2种试件的裂纹起裂时间、动态应力强度因子和裂纹扩展速度等参数进行计算和对比分析。分析发现，玻璃纤维提高了水泥石的断裂韧度、延迟了裂纹的起裂时间，对水泥石具有明显的强化效应。实验结果对研究水泥石的断裂力学属性特征具有一定意义。

英文摘要：

The reflected optical caustics method is applied to study dynamic fracture problems in hardened cement paste. First both the unreinforced cement paste and the glass fibres reinforced cement paste specimens were fabricated and the reflective coating on the surface of the specimen was prepared. Secondly the crack path and the shadow spot patterns during the crack propagation process for the two specimens were recorded by using a multi-spark high speed camera.Thirdly some dynamic parameters of two cement paste specimens including crack onset time the dynamic stress intensity factor and crack growth velocity were determined and analyzed comparatively.This indicates that the glass fibres can improve the fracture resistance and delay fracture time.These results will play an important role in evaluating the dynamic fracture properties of cement paste.