Concrete Plastic Shrinkage-Reduction Potential of Synergy Fibers

The contribution of synergy fibers to plastic shrinkage reduction of concrete was studied using cement-rich concrete, and the experimental results are reported. The fiber dosages were 0.5, 1.0, and 2.0 vol% of concrete. Three different batches of concrete were made, and 15 slabs were tested. The tests were conducted using slabs 51 mm (2.0 in.) thick, 1 m (3 ft) long, and 0.6 m (2 ft) wide. The crack development was enhanced by using fans that can produce a wind velocity of 22 km/h. The performance of these fibers was compared using the crack areas of control slabs with no fibers and fiber-reinforced slabs. The results indicate that synergy fibers, at the specified dosages, tremendously reduced the plastic shrinkage in concrete. The crack-area reduction varied from 100 to 92 percent of the plain concrete. There was absolutely no cracking when a fiber dosage of 2.0 vol% of concrete was used. There was 98 percent and 92 percent reduction of plastic shrinkage cracking when the fiber dosages were 1.0 percent and 0.5 percent, respectively, by volume of concrete.