EFFECT OF DIFFERENT FIBERS ON FROST RESISTANCE OF CONCRETE UNDER MULTIPLE FACTORS

In order to study the effect of steel fibers and polypropylene fibers on frost resistance of concrete under different environmental conditions, freeze-thaw media, fiber types, fiber contents and acted loads were chosen as variables. Based on the rapid freezing and thawing, the relative elastic modulus, mass loss, compressive strength, flexural strength and bending toughness of fiber reinforced concrete were determined. The results showed that the damage degree of concrete under different factors was ranked from large to small as:loads + chloride + freeze-thaw effect, chloride + freeze-thaw effect, and single freeze-thaw cycle effect, and mixing fibers could reduce freeze-thaw damage effectively. In the case of water freezing and salt freezing, the inclusion of polypropylene fiber could reduce the mass loss and the relative elastic modulus of concrete significantly. Adding 40 kg/m³ steel fibers into concrete matrices could improve the compressive strength and flexural strength after freeze and thaw cycles and improve the flexural toughness of concrete under combined action of loads, chloride salt and freeze-thaw cycles greatly, steel fibers could play a more important role in improving the mechanical properties than polypropylene fibers.