CHANGE IN SURFACE AIR PERMEABILITY OF CONCRETE WITH DIFFERENT MIX DESIGNS AND CURING

異なる配合と養生を与えたコンクリートの表層透気係数の経年変化

In this study, the change in surface quality of concrete with aging was studied using concretes with different mix designs, curing conditions and exposure conditions. The authors used three sets of specimens. The first set was composed of rectangular blocks. The second set was specimens that simulate a part of box culvert. The third set was column specimens of a middle-scale bridge model with RC rigid frame. These specimens were prepared with various mix designs and curing conditions in the Kanto area, Japan. The surface quality of concrete was evaluated by the coefficient of air permeability measured using the surface air permeability test proposed by Torrent Robert. Results showed that the difference in the air permeability owing to curing conditions decreased with age. About one year later, the coefficient of air permeability of specimens exposed to rainfall was approximately the same regardless of the curing method. The effect of curing was present even after one year for specimens under the roof-not exposed to rain, but the difference in the coefficient of air permeability continued to decrease. On the other hand, the difference in surface air permeability between concretes with different water to cement ratios remained even at the age of five years.本研究では、複数の配合・養生条件にて作製し、屋外に暴露した供試体を対象に、継続的に表層透気試験を実施することで、実環境に置かれたコンクリートの表層透気係数に及ぼす養生および配合の長期的な影響の把握を試みた。その結果、脱型時期や養生による表層透気係数の差は時間の経過とともに減少し、少なくとも脱型から約1年で明確な差は見られなくなった。養生によって初期の含水率は大きく異なるが、材齢の経過に伴い含水率や水和反応の進行程度の差が小さくなることに起因すると考察した。一方、水セメント比による影響は長期的であり、今回の検討の範囲内では少なくとも材齢5年6ヵ月の時点でも影響が残存することを確認した。

Language

  • English
  • Japanese

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 01667539
  • Record Type: Publication
  • Source Agency: Japan Science and Technology Agency (JST)
  • Files: TRIS, JSTAGE
  • Created Date: Mar 30 2018 3:03PM