• Proceedings of the Korea Concrete Institute Conference
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• 2008.11a
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• pp.777-780
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• 2008

According to the recent tendency that the buildings in the downtown are gradually Manhattanized, the very thick massive concrete is selected as the foundation of architectures. By the way, because this mass concrete cannot be simultaneously pour in a great quantity due to the circumstance at the field, not only the questions on the unification between the concretes pour on the upper layer and the lower layer are presented but also the cracks by the internal force from the difference of hydration exothermic period are occurred, which are pointed out as the problems. Thus, this study performed Mock-up test to apply the hydration heat controlling method of massive concrete for horizontal partition pouring construction to the building sites for the purpose of securing the stability on the cracks by the internal force from the difference of hydration exothermic period on the upper layer and the lower layer of massive concrete and checked the efficiency. As the results of test, in case of setting time difference method by super retarder with 2 layers and 4 layers, the effect that temperature gaps between upper part and lower part were lowered and the possibility of crack occurrence was decreased as the peak time of the heat of hydration became delayed to the latter term could be confirmed.

• Journal of Soil and Groundwater Environment
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• v.26 no.5
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• pp.20-28
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• 2021

Perfluorinated compounds(PFCs), an emerging environmental pollutant, are environmentally persistent and bioaccumulative organic compounds that possess a toxic impact on human health and ecosystems. PFCs are distributed widely in environment media including groundwater, surface water, soil and sediment. PFCs in contaminated solid can potentially leach into groundwater. Therefore, understanding PFCs partitioning between the aqueous phase and solid phase is important for the determination of their fate and transport in the environment. In this study, the sorption equilibrium batch and kinetic experiment of PFCs were carried out to estimated the sorption coefficient(K_d) and the fraction between aqueous-solid phase partition, respectively. Sorption branches of the PFDA(Perfluoro-n-decanoic acid), PFNA(Perfluoro-n-nonanoic acid), PFOA(Perfluoro-n-octanoic acid), PFOS(Perfluoro-1-octane sulfonic acid) and PFHxS(Perfluoro-1-hexane sulfonic acid) isotherms were nearly linear, and the estimated K_d was as follow: PFDA(1.50) > PFOS(1.49) > PFNA(0.81) > PFHxS(0.45) > PFOA(0.39). The sorption kinetics of PFDA, PFNA, PFOA, PFOS and PFHxS onto soil were described by a biexponential adsorption model, suggesting that a fast transport into the surface layer of soil, followed by two-step diffusion transport into the internal water and/or organic matter of soil. Shorter times(<20hr) were required to achieve equilibrium and fraction for adsorption on solid(F₁, F₂) increased with perfluorinated carbon chain length and sulfonate compounds in this study. Overall, our results suggested that not only the perfluorocarbon chain length, but also the terminal functional groups are important contributors to electrostatic and hydrophobic interactions between PFCs and soils, and organic matter in soils significantly affects adsorption maximum capacity than kinetic rate.