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日本ヒートアイランド学会論文集 Vol.17 (2022)

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Efflorescence on Cementitious Water-retentive Pavement Material Which Keeps Continuous Evaporation
Understanding of the efflorescence progression and the evaporative cooling performance degradation in outdoor experiments and the efflorescence thickness using X-ray diffraction

円井基史 Motofumi Marui*1 野呂 純二 Junji Noro *2 

*1 金沢工業大学 Kanazawa Institute of Technology

*2 株式会社 日産アーク Nissan Arc Ltd.


Through outdoor experiments using cementitious water-retentive paving block which keeps continuous absorption and evaporation, the progression of efflorescence, the effect on evaporative cooling performance, and the thickness of efflorescence (calcium carbonate) were investigated in this paper. The findings are as follows. 1) In the two outdoor experiments conducted under different climatic conditions, almost all of the pavement surface stained white (efflorescence) after about 9 to 10 months of exposure (integral amount of insolation was about 3000 MJ/m2). After efflorescence, it was confirmed that amount of evaporation decreased to 20 to 25% and the evaporative cooling performance was reduced compared to before efflorescence. 2) Through micro X-ray diffraction analysis, it was confirmed that the peak intensity indicating calcium carbonate was found to be larger and closer to the block surface as the exposure progressed at 4, 26, and 78 weeks. At 78 weeks of exposure, the thickness of calcium carbonate precipitated on the surface was estimated to be about 1.3 mm.