Abstract
A study on the effect of bleeding on the freeze-thaw resistance of concrete was conducted. The greater the amount of bleeding was, the worse the freeze-thaw resistance of the concrete became when changing the amount of bleeding through the partial substitution of limestone powder for fine aggregate or blending of two fine aggregates. Both the pore size distribution as measured by the mercury intrusion technique and the Vickers hardness of the transition zone around the coarse aggregate were insusceptible to the effect of bleeding in test pieces of φ100×200 mm, while the greater the amount of bleeding was, the bigger the air-void spacing factor became. It is assumed that the bleeding flow promotes defoaming and coalescence of the air voids entrained by the AE agent. Using the buoyancy method (Air Void Analyzer system), it was determined that the greater the amount of bleeding is, the higher the air void spacing factor tends to become in the first 1 to 3 hours after mixing, owing to the time dependence of the critical air void spacing factor of fresh concrete.
