EFFECT OF CONFINEMENT ON SILICEOUS AGGREGATE CONCRETE SUBJECTED TO ELEVATED TEMPERATURES AND CYCLIC HEATING

This paper describes an experimental study of the behavior of confined siliceous-aggregate concrete exposed to elevated temperature conditions such as those experienced during a fire. Locally produced gravel was used as coarse aggregates in the concrete specimens tests. Equally-spaced steel rings were employed in the cylinders to simulate the effect of confinement on the material. Three different types of concrete specimens were tested: plain concrete cylinder, cylinders with six rings, and cylinders with nine rings. The spacing between the rings is 28 mm and 17.5 mm for the six- and nine-ring specimens, respectively. The cylinders were exposed to cycles of heating and cooling up to 700 deg C. Results have indicated an improvement in the residual compressive strength up to about 30 percent and in the ductility of concrete at elevated temperatures due to the effect of confinement by ties.