This paper presents an experimental investigation on the influence of specimen and maximum aggregate size on concrete brittle fracture. Approximately 250 concrete specimens with various dimensions of (width x total depth x thickness) 105 X 105 X 12.5 mm to 1680 X 1680 X 200 mm made with various maximum aggregate sizes of 4.75, 9.5, 19, 38, and 76 mm were tested. The quasi-static loading-unloading tests were performed in a closed loop displacement control mode using a servo-hydraulic Instron machine equipped with two dynamic extensometers. Fractal dimensional analysis was done on the fracture surfaces of specimens using Image analyzing technique. A significant size effect was observed. For same size specimens, as the aggregate size increased, fracture parameters, i.e., critical energy release rate, G_(1c), and fracture energy, G_F increased. For same maximum aggregate size specimens, fracture parameters increased with increase in specimen sizes. Bridging and other forms of crack face interactions that are the most probable causes of high toughness, were more pronounced in the specimens with larger maximum size aggregates. Higher values of fractal dimension were reported for the specimens with bigger aggregates.
展开▼
机译：本文介绍了试样和最大骨料大小对混凝土脆性骨折影响的实验研究。大约250个混凝土试样，各种尺寸（宽度x总深度x厚）105 x 105 x 12.5 mm至1680×1680 x 200 mm，由4.75,9.5,19,38和76 mm的各种最大尺寸制成。使用配备有两个动态突出器的伺服液压Instron机器进行闭环位移控制模式进行准静态加载卸载测试。使用图像分析技术在试样的裂缝表面上进行分形尺寸分析。观察到大小的效果。对于相同尺寸的标本，随着骨料尺寸增加，断裂参数，即临界能量释放率，G_（1C）和裂缝能量，G_F增加。对于相同的最大骨料大小标本，裂缝参数随着样品尺寸的增加而增加。桥接和其他形式的裂缝面相互作用是最可能的高韧性的原因，在具有较大的最大尺寸聚集体的标本中更加明显。报告了具有更大聚集体的标本的分形维数值。
展开▼
