INFLUENCE OF CARBONATION AT EARLY AGES ON DEPTH DISTRIBUTION OF OXYGEN DIFFUSION COEFFICIENT OF HARDENED CEMENT PASTE

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  • YOKOZUKA Kiyonori
    GUNMA UNIVERSITY, Graduate School of Engineering, Department of Civil and Environmental Engineering
  • LI Chun-He
    GUNMA UNIVERSITY, Graduate School of Engineering, Department of Civil and Environmental Engineering
  • NAKARAI Kenichiro
    GUNMA UNIVERSITY, Graduate School of Engineering, Department of Civil and Environmental Engineering

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Other Title
  • 若材齢時の炭酸化がセメント硬化体の酸素拡散係数の深度分布に及ぼす影響

Abstract

In this study, the influence of drying and carbonation at the early ages on depth distribution of the oxygen diffusion coefficient of the hardened cement paste was investigated. In the experiment, mortar specimens, water cementitious material ratio is 45％, with/without blast furnace slag, were prepared and then exposed drying condition of with/without CO2 after 24 hours sealed curing. After that, the depth distribution of the saturation degree, pore structure, oxygen diffusion coefficient in each specimen was measured and the influence of drying and carbonation was discussed. As a result, it was suggested that the change in the pore structure and the oxygen diffusion coefficient due to drying and carbonation at the early age were governed by the mixture effect of moisture loss, hydration and carbonation. The specimen only the Portland cement showed minute tendency that oxygen diffusion coefficient deteriorated by influence of the carbonation, and the specimen having blast furnace slag as binder, the increase in the oxygen diffusion coefficient by the carbonation occurred in the deeper area than the specimen without blast furnace slag. Because a hydration product of the blast furnace slag carbonated, the pore structure that became coarse let it accelerate water fugacity of the internal specimens and let coarse pores increase more.

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