Effect of re-vibration compaction on improving concrete quality and verification of its application for deck construction

Re-vibration timing and duration are important factors to improve or maintain the quality of concrete. The present study proposes a method by which the resistance value of fresh concrete is measured to easily determine the timing of re-vibration at the site, and to clarify the optimal timing and duration of re-vibration. The effect of re-vibration on the fresh and hardened properties of the concrete were determined. For fresh properties, concrete resistance value by penetration test and measurement of bleeding water was performed. After the concrete was hardened, compressive strength test, air void spacing, chloride penetration test and electrochemical resistivity test of concrete surface were performed to evaluate the durability. A fresh concrete resistance value of 17×10 -3 N/mm 2 corresponded to an optimum time for initiating re-vibration and its duration, which enhanced the bleeding amount and improved the fresh state of concrete by expelling coarse voids while retaining useful entrained air. Re-vibration corresponding to this value increased the surface resistivity of concrete and reduced the chloride diffusion coefficient. Furthermore, this technique was applied on to a bridge deck concrete to grasp the effect on the actual construction. Re-vibration corresponding to fresh concrete resistance value of 17×10 -3 N/mm 2 was performed and the properties of fresh and hardened state of the deck were examined. The bleeding amount and other re-vibration characteristics were consistent with the laboratory results. Hence, this method can be efficiently adopted during the construction of bridge decks. • Timing of re-vibration was determined according to the resistance of fresh concrete, which is a measure of its setting time. • Re-vibration timing had an optimum level at which desired strength and durability properties were achieved. • Re-vibration reduced coarse air voids by promoting bleeding and retaining useful entrained air. • Re-vibration technique could be easily applied to actual bridge deck construction. • Bleeding enhanced the density of concrete and improved the compressive strength.