Durability of concrete is mainly influenced by its permeability. High performance concrete (HPC) is generally considered to be a highly durable material, owing mainly to its low permeability. However, when exposed to fire, HPC is highly vulnerable to the phenomenon…
Durability of concrete is mainly influenced by its permeability. High performance concrete (HPC) is generally considered to be a highly durable material, owing mainly to its low permeability. However, when exposed to fire, HPC is highly vulnerable to the phenomenon of explosive spalling. The transport of fluids inside concrete is hindered by low permeability of HPC. Permeability measurements on concrete are mainly performed at room temperature, only scarce information is available on permeability of HPC at elevated temperatures. In the present paper, a new test setup for permeability measurements at elevated temperatures is presented. Two different 3 types of concrete, namely plain HPC and HPC with 1kg/m of polypropylene fibres, were tested up to temperatures of 300°C. It was observed that the melting of fibres is not the only reason for the 3 prevention of explosive spalling. Additionally, experiments were conducted on 700x700x300 mm slabs in order to investigate the performance of HPC without and with PP fibres. Furthermore, using the thermo-hygro-mechanical model for concrete the phenomenon of explosive spalling was numerically investigated. Influence of permeability and relative humidity on various aspects of explosive spalling was investigated and the findings are reported.