Thesis: Discrete element modelling of asphalt concrete reinforced with fiber glass grids

PhD defense: Guixian LIU

Title: Discrete element modelling of asphalt concrete reinforced with fiber glass grids

Team: GC-E

Abstract: The effect of fiberglass grid reinforcement in asphalt concrete is studied numerically by discrete element method in this work. Firstly, concerning on the quasi-brittle material, the elasticity of modelling are calibrated, and the rupture behaviour is verified with linear elastic fracture mechanics. Then the simulations of wedge splitting tests are performed under monotonic load. The interface elasticity and failure dominate in the fracture propagation of samples, which gives rise to a simplified interface model. The parameter calibration on Young’s modulus and Poisson’s ratio is conducted between interface model and discrete element method. Through the fitting with experimental results, the interface strength and energy release rate are also identified by discrete element method and simplified interface model. Comparing with linear elastic fracture mechanics, the interface rupture presents more released energy. The strength and energy release rate are reduced because of the application of the fiber glass grid. The fatigue behaviour is studied by simulations of 4-point bending fatigue tests. Bodin’s fatigue model ‘L2R’ is adapted with discrete element method. The effect of each parameter on the damage evolution is studied respectively. The fiber glass grid helps to extent the fatigue life mainly after the fatigue cracks cross the grid. The interface effect is observed on prolonging the fatigue life of all the phases. From both monotonic and fatigue tests, it indicates that good bonding between two asphalt concrete layers is important to the resistance of rupture.

The jury is composed of:

• Cyrille Chazallon, supervisor, professor, INSA  Strasbourg
• Georg Koval, advisor, associate professor, INSA Strasbourg
• Ali Daouadji, co-supervisor, professor, INSA Lyon
• Frédéric Ragueneau, professor, ENS Cachan
• Yannick Descantes, reviewer, researcher, HDR, IFSTTAR
• François Chevoir, reviewer, senior researcher, IFSTTAR

The defense will be held, in English, on Thursday, 23th Mai at 13:30 pm in the amphitheater "Arts et Industries" of INSA Strasbourg.