Insights into the fracturing process of plain concrete under crack opening

The complex process of fracture occurring in heterogeneous quasi-brittle material concrete under splitting tensile load is researched using the acoustic emission (AE) and digital imaging tools. Analyses of the AE events and energy reveal four stages of fracture under opening mode-elastic stage, growth of microcracks, stable crack growth and major crack growth until final failure. In the stable crack growth stage simultaneous microcracking and their coalescence into macrocracks take place. The dimensions and shape of the fracture process zone (FPZ) are determined through the distribution of acoustic emission events and their kernel density contours. Assuming a logistic or sigmoid law for the growth of micro and macro cracks, the b-value is seen to increase steadily reaching a constant magnitude close to failure. The growth of logistic b-value is found to follow the crack growth curve indicating its use in predicting failure.

Automated summary

The complex process of fracture occurring in heterogeneous quasi-brittle material concrete under splitting tensile load is researched using the acoustic emission (AE) and digital imaging tools. Analyses of the AE events and energy reveal four stages of fracture under opening mode-elastic stage, growth of microcracks, stable crack growth, and major crack growth until final failure. The growth of logistic b-value is found to follow the crack growth curve indicating its use in predicting failure.