Repairing post-heated L-shaped RC columns with advanced thin concrete jacketing

Abstract

L-shaped reinforced concrete columns lose strength rapidly after exposure to high levels of fire due to their large surface area. An experimental investigation was performed to evaluate two types of concrete jacketing for the distorted columns. Eight half-scale L-shaped reinforced concrete columns were exposed to 400 °C and 600 °C for two hours following the ASTM standard, and one column served as a reference. Thin reactive powder concrete (RPC) and self-compacting concrete (SCC) jackets were used to repair the post-heated columns. The stiffness of the column repaired with a fibrous SCC jacket after exposure to 400 °C exhibited the same stiffness as the non-heated control column, while the stiffness and capacity of the repaired column after exposure to 600 °C were less than those of the non-heated column. Fibrous RPC jacketing of columns exposed to 400 °C and 600 °C increased the column ultimate capacity by 33% and 14% over that of the non-heated control column, respectively. However, fibrous SCC jacketing could only restore the ultimate capacity for columns exposed to 400 °C. Adding steel fibre to the concrete jacket mix significantly improved the repaired column capacity.