Crack propagation in concrete mortar under quasi-static tensile loading: experimental insights and phase-field modeling

This study investigates crack propagation in concrete mortar under quasi-static tensile loading with imposed displacement. Several rectangular cubic concrete specimens containing a predefined crack and hole were cast and tested. The load–displacement curves and crack paths were obtained experimentally and analyzed, enabling us to assess the influence of the specimen age parameter on fracture behavior. The evolution of mechanical properties as a function of age, in particular the modulus of elasticity <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>E</mml:mi> </mml:math> and Poisson’s ratio <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:mi>ϑ</mml:mi> </mml:math> (characterized by ultrasonic testing), was monitored. The fracture energy <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML"> <mml:msub> <mml:mi>G</mml:mi> <mml:mi>c</mml:mi> </mml:msub> </mml:math> was determined by direct tensile testing. These parameters were fed into a phase field model implemented by the finite element method in a computational code developed in MATLAB®. The solution is based on a variational system that treats the displacement and damage fields in an alternating minimization scheme. The numerical results were compared in two distinct frameworks: one in a logical domain and the other in a physical domain. Finally, the results obtained in each of these frameworks were compared with experimental results, revealing relatively good agreement.