Assessing the residual fracture properties of thermally damaged high strength concrete

• Mechanical properties of concrete degenerates after exposure to high temperatures.
• The failure behavior and the size effect of thermally damaged concrete change.
• The experimental investigation has been supplemented by numerical analysis.
• The initial fracture energy, the tensile strength and the characteristic length has been identified.
• The higher the thermal damage the more ductile the failure behavior.

Experimental investigations and numerical analyses of a white high strength concrete specimens after exposure to high temperatures and the evaluation of its residual properties are presented. Heated and non heated, notched and unnotched specimens were tested for uniaxial compression, direct and indirect tensile tests at ambient conditions approximately one day after the exposure to the high temperature. For interpreting the results of the experimental investigation the symmetric over-nonlocal formulation of a microplane model has been adopted. The initial fracture energy, the tensile strength and the characteristic length has been identified showing that the material failure mode changes: the higher the thermal damage the more ductile the failure behavior.