A method to reduce plastic shrinkage cracking of concrete using re-vibration technique

One of the problems that reduce durability; thus, performance of concrete is the development of plastic shrinkage cracking (PSC). Traditionally, the development of PSC has been minimized by controlling its exposure to weather conditions or by adding fibers. In this study, concrete re-vibration was used as an alternative technique to control PSC because of the limited availability of fibers in the developing countries. In this study, the wait time after slab casting and before vibration was selected to be 90 minutes while length of re-vibration time was varied from 15 to 45 seconds. Also, the water-cement ratios were selected to be 0.5, 0.55 and 0.6. The slabs were cast based on the form dimensions proposed by ASTM C1579 criteria. Image analysis of cracks was performed to process digital images of the cracks' widths and lengths to estimate crack growth. Cracks widths and lengths were unevenly reduced based on the water-cement ratios and the lengths of re-vibration. Re-vibrated and fibered slabs showed similar reduction in cracks dimension. This technique and the fact that re-vibrating is cheaper than adding fibers makes the proposed approach a very suitable alternative for controlling plastic shrinkage cracks, especially in arid regions of the world.