DEVELOPMENT OF STEEL FIBER-REINFORCED SELF-CONSOLIDATING CONCRETE FOR REPAIRING PURPOSES

Abstract

Fifteen self-consolidating concrete (SCC) as well as five steel fiber-reinforced self-consolidating concrete (SFR-SCC) mixes using full-length crimped steel fibers were developed and tested in order to optimize a suitable (SFR-SCC) mix for repair of beams. Water-cementitious materials (w/cm) ratio, sand/coarse aggregate ratio and presence of basalt dust were the main variables taken into consideration. The test results showed that the mix design for the SCC mixes without steel fibers can be achieved by satisfying the flowability criterion. But for the design of self- consolidating concrete mixes with steel fibers , both the flowability and passing ability criteria must be satisfied. Basalt dust was found to be necessary for SCC mixes without fibers with sand/coarse aggregate ratios of 0.9 and 0.8, and also for developing SCC mixes with crimped steel fibers. SFR-SCC mix with sand/coarse aggregate of 1.1 had satisfactory results in both fresh and hardened properties. SFR-SCC mixes with sand/coarse aggregate of 0.9 and 0.8 did not satisfy fresh properties criteria even with dust/coarse aggregate ratio of 0.4. The suggested SFR-SCC mix was used to repair a beam cracked due to shear stresses. For this purpose, two RC beams were cast and tested under three-point loading. One beam was tested as control beam and the other beam was repaired using the suggested mix. The inclined cracking and ultimate load of the repaired beam were increased by 87.5% and 91% comparing to the control beam, respectively. The flexural stiffness was increased significantly for the repaired beam comparing to the control beam. The test results also showed the great contribution of SFR-SCC in both compression and tension zones. Keywords: full-length crimped steel fibers, self-consolidating concrete, steel fiber-reinforced self-consolidating concrete, shear repairing.