A coupled chemo-mechanical damage-healing model for cementitious materials

• Published in: Computational Modelling of Concrete Structures pp. 285 - 288
• Main Authors: Jefferson, A.D., Davies, R.E.
• Format: Book Chapter
• Language: English
• Published: CRC Press 2018
• Edition: 1
• Subjects: ASR Gel; Coupled Model; CDF; Discrete Cracks; Strong Discontinuity; ASR Expansion; Incremental Area; Healed Material; Stick Slip Behaviour; Stress Free State; CMOD; Continuum Damage Mechanics; Cohesive Zone Model; Unreinforced Specimens; Fracture Process Zone; Relative Displacement Vector; Autogenous Shrinkage; Cohesive Zone; Cardiff University; Crack Openings; Cementitious Materials; Capillary Flow; FRC; Wall Slip; Deformed Mesh
• ISBN: 9781138741171; 1138741175
• DOI: 10.1201/9781315182964-35

A model is described for representing simultaneous damage and healing behaviour in cementitious structural elements that contain embedded autonomic healing systems. The model uses a crack-healing cohesive zone formulation in which damaged and healed proportions of the cohesive zone can both grow and diminish, with no restrictions placed on the number or timing of these damage-healing events. The cohesive zone sub-model is implemented in a finite element with strong discontinuity and is coupled to both capillary flow and chemical curing model components. The flow model simulates the transport of healing agents within discrete cracks as well as through micro-cracked regions within the fracture process zone. An important aspect of the damage-healing component of the model is the way that permanent strains are computed so as to satisfy the second law of thermodynamics. This is accomplished with the assumption that the stress in a component of healing agent is zero at the moment of solidification, which applies to both null and non-zero displacement fields. The new coupled model is assessed using some recent data obtained from a number of experiments undertaken at Cardiff University. These tests were conducted on both reinforced and unreinforced specimens, and encompass a range of cracking scenarios. The paper shows that the model accurately predicts the flow of healing agents within discrete cracks and that it is able to represent the mechanical behaviour associated with multiple and simultaneous damage-healing events with good accuracy. This chapter describes a model for representing simultaneous damage and healing behaviour in cementitious structural elements that contain embedded autonomic healing systems. The model uses a crack-healing cohesive zone formulation in which damaged and healed proportions of the cohesive zone can both grow and diminish, with no restrictions placed on the number or timing of these damage-healing events. The cohesive zone sub-model is implemented in a finite element with strong discontinuity and is coupled to both capillary flow and chemical curing model components. The coupled model brings together a formulation for simulating the capillary flow of healing agents in discrete cracks with a mechanical damage-healing model component. The full experimental series encompasses a number of test arrangements and investigates healing at different loading rates, curing conditions, crack openings and crack geometries. Based on the results obtained, the authors believe that the model is able to simulate the type of continuous and simultaneous damage-healing behaviour with good accuracy.