Post-heating strength of fiber-reinforced concretes

The strength reduction of high-strength concrete can be different from that of normal-strength concrete. The investigation was directed toward the study of the residual compressive strength and surface cracking of fiber-reinforced concretes subjected to high temperatures. Six different concrete mixes were tested over a compressive strength range from 60 to 74.7 N/mm2. The test variables were concrete composition, type of fiber reinforcement (polypropylene fibers Ø=0.032 mm, ℓ=18 mm; or Ø=1.1 mm, ℓ=40 mm; steel fibers: Ø=1.1 mm, ℓ=18 mm; Ø=0.9 mm, ℓ=35 mm; Ø=0.3 mm, ℓ=12.5 mm) and maximum temperature (20 °C, 50 °C, 150 °C, 200 °C, 300 °C, 400 °C, 500 °C, 600 °C, 800 °C). The test results indicate that the advantageous effects of polypropylene and steel fibers in concrete subjected to high temperatures are mainly observed for thin fibers and not for thick fibers. Strength reduction and surface cracking are detailed for the various tested fiber-reinforced concretes.

► Fibers play an important role for concrete and for high strength concrete.
► Our study was directed to study compressive strength and cracking of FRC.
► Our results suggested the advantageous influence of thin polymeric fibers.
► Thin and short steel fibers contributed to the post-heating compressive strength.