2018 Volume 72 Issue 1 Pages 233-239
Recently research has reported that the air content in ready-mixed concrete decreased by the pumping during construction process. It is possible that salt scaling resistance of concrete structure is degraded from decrease of air content by the pumping during construction process. In this research, We discussed about the change of scaling resistance by the pumping. Mortar which was temporarily pressurized during fresh was evaluated the salt scaling resistance. In the case of AE（entrained air）mortar, the salt scaling resistance was decreased by pressurization. In particularly, the salt scaling resistance of AE mortar that was pressurized by 0.4MPa was remarkably decreased. Decrease in salt scaling resistance of AE mortar by the pressurization had happened by decrease in entrained air of 150μm or less and increase in spacing factor of air voids by the pressurization. It is thought that decrease in entrained air by pressurization was caused because entrained air becoming smaller by the external pressure, becoming unstable, and dissolved into the surrounding mixing water. In the case of mortar using entrained air and microsballoon in combination, decrease in salt scaling resistance by the temporarily pressurization was smaller than AE mortar. Probably, using of microballoon to mortar prevented of decrease in the air content of 80μm or less by the pressurization, allowing decrease in salt scaling resistance was suppressed.
