カルシア焼結体の炭酸化及び耐水和性の改善

概要

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Two kinds of CaO clinkers, with 70% (low) density and 95% (high) density, were prepared and treated at 500-800℃ in a carbon dioxide atmosphere. The low-density clinker was carbonated both on the exterior surface and inside the pores, with each CaO grain being encompassed by a layer of CaCO_3 film; whereas the high-density one was only carbonated on the exterior surface with a lower rate. The carbonation processes for both samples were controlled by the diffusion of CO_2 through the formed CaCO_3 film. The carbonation rate increased with temperature rising, and reached the maximum at 700℃. The microstructure of the formed CaCO_3 film was significantly affected by carbonation temperature, and a dense texture of CaCO_3 with grains about 2 μm in thickness was obtained at 700℃. Slaking test showed that the carbonated sample with low-density was easily broken due to the weak bond among the carbonated grains in spite that the hydration resistance was improved. For the high-density sample, the hydration resistance was improved significantly after this treatment. An induction period of 7 d was achieved and the sample was not broken after 21 d slaking at 70℃ in 90% humidity.
社団法人日本セラミックス協会の論文
2002-06-01