The effect of fibers on the variation of bond between steel reinforcement and concrete with casting position

Bond to plain and deformed steel rebars was measured by pull-out testing along the height of wall-shaped specimens. The performances of steel, polypropylene and glass fiber reinforced concrete were compared with non-fiber concrete. The results did not indicate significant difference in the behavior of the concretes with plain bars. The differences in the bond with deformed bar were correlated with the cracking patterns as a function of fiber type and casting position. Steel fiber concrete had the highest bond reduction with concrete depth despite the highest bond strength, which was attributed to the segregation of steel fibers.

Research highlights
► Fibers did not affect the bond reduction of plain bars with casting position.
► The bond strength of deformed bars was higher in steel fiber concrete.
► Steel fiber concrete was more affected by top-bar effect due to segregation.
► Pull-out cracking was affected by the fiber type and casting position.
► Cracking pattern was correlated to bond strength.