A Method to Reduce Plastic Shrinkage Cracking of Concrete Using the Re-Vibration Technique

One of the phenomena that reduces durability of concrete is plastic shrinkage cracking (PSC). Traditionally, the initiation and propagation of PSC has been controlled by minimizing its exposure to detrimental weather conditions or by adding fibers. In this study, concrete re-vibration technique was used, as an alternative, to reduce development of PSC because of the limited availability of fibers in developing countries. The time of re-vibration was selected to be 90 minutes after casting of slab which was based on ASTM C1579 procedure. The length of re-vibration was varied from 15 to 45 seconds. To identify influence of water on PSC, the water-cement ratios were selected to be 0.5, 0.55 and 0.6. In addition, an image analysis approach was implemented to process digital images of the cracks to estimate crack widths and lengths. The test results showed that the cracks' widths and lengths were reduced depending on the water-cement ratios and the re-vibration time lengths. Both fibered and re-vibrated showed similar levels of PSC reductions. Since both techniques reduced PSCs to similar levels, it is proposed to use re-vibration technique because it is more cost-effective in developing countries.