Steel Ring-Based Restraint of HSC Explosive Spalling in High Temperature Environments

This paper reports on an experimental study regarding the behavior of restrained high-strength concrete in response to the type of extreme heating associated with fire. The study was intended to support estimation of thermal stress from the strain in a restraining steel ring and vapor pressure in restrained concrete under the conditions of a RABT 30 rapid heating curve. The size of the specimens was φ300 X 100 mm, and the results showed that explosive spalling occurred between 4 and 10 minutes in terms of heating time. It was also observed that the thermal stress was greater than the vapor pressure value of 0.1 MPa at a point 10 mm from the heated surface at 5 minutes. The maximum spalling depth was about 61 mm. It was inferred that spalling behavior caused by thermal stress may become predominant under restrained conditions.