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 silicieous-aggregate concrete exposed to elevated temperature conditi ons such as those experienced during fire. Locally produced gravel was used as coarse aggregates in the concrete specimens tested. Equally s paced steel rings were employed in the cylinders to simulate the effec t of confinement on the material. Three different types of concrete sp ecimens were tested: plain concrete cylinder, cylinders with six rings , and cylinders with nine rings. The spacing between the rings is 28 a nd 17.5 mm for the six- and nine-ring specimens, respectively. The cyl inders were exposed to cycles of heating and cooling up to 700 C. Resu lts have indicated an improvement in the residual compressive strength up to about 30 percent and in the ductility of concrete at elevated t emperatures due to the effect of confinement by ties.