A Fundamental Study of the Evaluation of Toughness for Fiber Reinforced Concretes

纤维混凝土韧性评价的基础研究

基本信息

批准号：
02555106
负责人：
KAWAMURA Mitsunori
金额：
$ 4.61万
依托单位：
Kanazawa University
依托单位国家：
日本
项目类别：
Grant-in-Aid for Developmental Scientific Research (B)
财政年份：
1990
资助国家：
日本
起止时间：
1990 至 1991
项目状态：
已结题

来源：
https://kaken.nii.ac.jp/grant/KAKENHI-PROJECT-02555106/
关键词：
The Critical Strain Energy Release Rate Interfacial Zone Microhardness Me*asurement Backscattered Electron Image Fluorescent Microscopy Debonding Frictional Stress Silica Fume 破壊靭性集束繊維引張軟化曲線新素材繊維

项目摘要

The significance of the bond properties between fibers and cement matrix in the toughness of fiber reinforced concretes was investigated. The bond of fiber with the matrix was characterized by the fracture toughness (i. e. the critical strain energy release rate) for the interfacial zone and the frictional shear stress along the debonded interface. Those properties were discussed relating them to the microstructure formed around fibers. The microstructure formed in the vicinity of fibers are elucidated by the microhardness measurements, BEI analysis and fluorescent microscopy.The major results obtained in this study are summarized as follows :(1) It was possible to evaluate experimentally the critical strain energy release rate for the interfacial zone from the single fiber pull-out test based on the compliance method.(2) The critical strain energy release rate for the interfacial zone between fibers and cementitious matrix appears to sensitively reflect the characteristics of the interfacial zone.(3) The addition of silica fume and the reduction of water/cement ratio of the matrix resulted in the dense microstructure of the interfacial zone. However, the dense interfacial zone formed by the addition of silica fume did not lead to the increase in fracture toughness for the interfacial zone.(4) Fracture toughness for the interfacial zone is affected by the incorporation of sand grains.(5) Observations for the interfacial zone under the fluorescent microscope revealed that the mode of bond failure was not a simple shear failure which has been assumed in the theoretical studies for the single fiber pull-out process.(6) Further work is needed to theoretically discuss the complex phenomena of debonding with the fluorescent microscope.

研究了纤维和水泥基质之间的键特性在纤维增强混凝土韧性中的重要性。纤维与基质的键具有界面区域的断裂韧性（即临界应变能释放速率）和沿剥落的界面沿摩擦剪切应力的特征。讨论了这些属性，将它们与围绕纤维形成的微观结构有关。通过微硬度测量，BEI分析和荧光显微镜阐明了在纤维附近形成的微观结构。在这项研究中获得的主要结果总结如下：（1）可以通过实验评估实验的关键应变能释放速率的关键应变率基于合规方法的单纤维拉出测试的界面区域。（2）纤维和水泥矩阵之间界面区域的临界应变能释放速率似乎敏感地反映了界面区域的特征。（3）添加剂的特性。二氧化硅烟气和基质的水/水泥比的还原导致界面区的密集微观结构。但是，通过添加二氧化硅烟粉形成的密集界面区并没有导致界面区域的裂缝韧性增加。（4）界面区域的断裂韧性受掺入沙粒的影响。（5）观察结果。（5）观察结果。荧光显微镜下的界面区表明，键失败的模式不是一个简单的剪切故障，这是单个纤维拉出过程的理论研究中假定的。（6）理论上需要进一步的工作来讨论复杂现象用荧光显微镜脱键。