With compressive strength grade of C40, C60, and C70, respectively, normal-strength concrete (NSC) and high-strength concrete (HSC) were used to investigate compressive strength, splitting tensile strength, and bending strength after high temperature. The oil furnace is used in this study. Its temperature-time curve is close to standard curve, which conforms to Chinese standard GB/T 9978-1999. After being heated to temperatures of 200, 400, 600, 800, and 1000 degreesC, respectively, the mechanical properties of HSC were tested. The influence of temperature, water content, specimen size, strength grade, and temperature profiles on mechanical properties of HSC are discussed. (C) 2004 Elsevier Ltd. All rights reserved.