Effect of High Standard of Temperature on the Hardened Needled Concrete

Fibers are usually used to reinforce concrete. the study shows the using of needles for reinforcing high-strength concrete (60mpa) when the samples are exposed to temperatures (100°c and 400°c) with a percentage of needles (0%, 0.5% and 1%) compared with the conditions of room temperature (25°c). they study shows that the compressive strength decreases by about (0.94% and 17.6%) for (0% needle (steel fiber)) at 100°c and 400°c, respectively. the compressive strength decreases by about (1.7% and 15.9%) for (0.5% needle (steel fiber)) at100°c and 400°c, respectively. the compressive strength decreases by about (0.3% and 14.2%) for (1% needle (steel fiber)) at 100°c and 400°c, respectively. all the above-mentioned results are compared with cubes tested at room temperature (25°c). based on the results of this work, the tensile strength decreases by about (0.49% and 6.65%) for (0% needle (steel fiber)) at 100°c and 400°c, respectively. the tensile strength decreases by about (0.73% and 6.1%) for (0.5% needle (steel fiber)) at 100°c and 400°c, respectively. the tensile strength decreases by about (0.24% and 5.54%) for (1% needle (steel fiber)) at 100°c and 400°c, respectively. all the above-mentioned results are compared with cubes tested at room temperature (25 °c). the flexural strength decreases by about (1.08% and 26%) for (0% needle (steel fiber)) at 100°c and 400°c, respectively. the flexural strength decreases by about (2.1% and 26.3%) for (0.5% needle (steel fiber)) at 100°c and 400°c, respectively. the flexural strength decreases by about (3.1% and 24.7%) for (1% needle (steel fiber)) at 100°c and 400°c, respectively. all the above-mentioned results are compared with cubes tested at room temperature (25°c).