Abstract
The purpose of this study is to investigate the effect of combined use of vinylon short-fibers and micro-fibers on the freezing and thawing resistance of fiber-reinforced porous concretes. The fiber-reinforced porous concretes using vinylon short-fibers with the length of 40mm（F40） and micro-fibers with the length of 12mm（F12）are prepared with the target voids of 20％, F40 contents of 0, 0.3, 0.5％ and F12 contents in binder of 0, 0.4, 0.6, 1.2％. The fiber-reinforced porous concrete specimens are cured under 20℃ moist for 24h, 70℃ hot water for 1d and 20℃ water for 1d, and subjected to the freezing and thawing resistance test. The relative dynamic modulus of elasticity and reduction in mass of the specimens are measured during the test. After the freezing and thawing test, the specimens are tested for flexural strength and flexural toughness. As a result, the fiber-reinforced porous concrete combined use of F40 with the content of 0.3％ and F12 with the content of 0.4％ gives superior freezing and thawing resistance by evaluating the relative dynamic modulus of elasticity. The flexural properties of the fiber-reinforced porous concrete after the freezing and thawing test are improved by combined use of F40 with the content of 0.5％ and F12 with the content up to 1.2％. The freezing and thawing resistance of porous concrete is considerably improved by combined use of the vinylon short-fibers and micro-fibers with the proper fiber contents.
