Recovery Behavior of Hybrid Fiber Reinforced High Strength Concrete After Fire Exposure

High-strength concrete shows particular characteristic behavior at elevated temperatures, such as explosive spalling, that is rarely observed in normal-strength concrete. This behavior has been attributed to the very dense concrete matrix usually associated with high-strength concrete. Recently the addition of polypropylene fibres into high-strength concrete was reported to be very effective against the explosive spalling. However, it is hopeless to maintain the residual strength and the fracture toughness when the fibres melt. Steel fibre reinforcement can help to maintain the residual strength and fracture toughness after heated. In this paper, hybrid fibre reinforcement with the combination of polypropylene and steel fibres is proposed for improving the strength as well as the fracture characteristics after heating. This paper investigates the recovery possibility, up to 6 months observation, of heated hybrid fibre reinforced high-strength concrete. Tests results of hybrid fibre reinforced concrete showed significant recovery possibility on the physical properties and the permeability after high temperature.