Test results and model for the residual compressive strength of concrete after a fire

An investigation into temperature induced degradation of the compressive strength of concrete including that under cooling phase is carried out. The paper gathers and reviews a considerable amount of test data, considering the influence of different test parameters such as initial compressive strength, aggregate type, cooling regime and specimen shape. It is found that the compressive strength of concrete at high temperature is in accordance with the model proposed in the Eurocodes for calcareous concrete. However, during cooling phase, an additional reduction of compressive strength in concrete is observed, which can be as high as 20% of the initial strength for elevated temperatures around 500°C. Finally, a generic concrete model for temperature dependent compressive strength, accounting for both growth and cooling phase of temperature is proposed. The model can be used for simulating fire response of concrete structures subjected to natural fires or for the evaluation of residual load capacity of concrete structures after fire.