Use of Fibers and Welded-Wire Reinforcement in Construction of Slabs on Ground

摘要

Different types of fiber-reinforced concrete have been advocated and used as a replacement for welded-wire reinforcement (WWR) in slabs on ground, leading at times to conflicting opinion and/or unrealistic expectation about the benefits of using either WWR or different types of fiber in slabs. In order to verify some of these opinions, tests have been carried out on model slabs (2.5 m X 2.5 m X 150 mm thick) cast on grade in a test pit and loaded to failure. Results are compared to evaluate the load-carrying capacity for slabs having equivalent amounts of either WWR, fibrillated polypropylene fibers, or steel fibers. Test results show that steel fibers are a suitable alternative to using properly positioned WWR. However, use of polypropylene fibers at a low dosage, which is most common for slab construction (0.9 kg/m~3), provides little benefit in terms of increased load-carrying capacity when compared with a plain unreinforced slab. Slab capacity is affected mainly by the postcracking strength of the concrete section, and results from flexure beam tests give a good indication of expected behavior of slabs. The test results also show that a poor subgrade support can be compensated by reinforcing a slab with a moderate amount of either WWR or steel fibers (at a dosage of 30 kg/m~3).