Abstract:The effect of cracks in steel fiber concrete(SFRC) and high ductility and low shrinkage material(LSECC) on Cl- penetration was investigated by pre induced flexural cracks in concrete beams. The cracked beams with different crack width or tensile strains were then continuously soaked with 3%(by mass) NaCl solution or undergone drying and wetting cycles. The content(by mass) of Cl- in concrete at the locations of cracks was determined by drilling powder sample with electric hammer. The experimental results show that the influence of cracks on the Cl- penetration is very significant. The content of Cl- at the location of cracks in SFRC is 34 times compared to the place without cracks. The Cl- content in SFRC is increased with increase of the crack width for the specimens soaked for 30 d. At 60 d after soaked, the content of Cl- becomes almost constant irrespective of the penetration depth. Under drying and wetting conditions, the content of Cl- in SFRC greatly increases compared to those of continuously soaked. By contrast, LSECC can apparently reduce the content of Cl-, especially under drying and wetting conditions. The resistance to Cl- penetration for LSECC is obviously significant.