http://chineseinput.net/에서 pinyin(병음)방식으로 중국어를 변환할 수 있습니다.
변환된 중국어를 복사하여 사용하시면 됩니다.
Effects of Relative Humidity and Temperature on the Transport of Chloride in the Concrete
남진각,William H. Hartt,김기준 한국콘크리트학회 2005 콘크리트학회논문집 Vol.17 No.5
To investigate the role of RH and temperature on the transport of chloride in the concrete, two groups of specimens were configured. For both groups, mix design was based on w/c=0.45, 400kg/m3 cement, 794kg/m3 fine aggregate and 858kg/m3 coarse aggregate. After specimen fabrication these were exposed to four different RH (35, 55, 75 and 95% RH) and temperature (0, 20, 30 and 40 C) conditions. After 3 and 6 months 15% NaCl exposure 5mm cores were taken. These cores were sliced and individual cores were ground to powder. In addition, to evaluate the effect of temperature on the chloride binding some powder samples were leached in the each of four temperature chambers. Chloride titration for these was performed using FDOT acid titration method. Based upon the resultant data conclusions were reached regarding that 1) effective diffusion coefficient, De, increased with increasing exposure RH, suggesting that the size and number of water paths increased with elevated moisture content in the specimens, 2) De increased with increasing temperature in the range of 0 to 40C possibly by elevated thermal activation of chloride ions and reduced chloride binding at higher temperature, 3) water soluble chloride concentration, [Cl-]s, increased with increasing temperature, and 4) chloride concentration profile for initially dry concrete specimens was higher than for the initially wet ones indicating pronounced capillary suction (sorption) occurred for the dry concrete specimens.
남진각,William H. Hartt,김기준 한국콘크리트학회 2005 콘크리트학회논문집 Vol.17 No.5
A series of reinforced G109 type specimens was fabricated and ponded with a 15 weight percent NaCl solution. Mix design variables included 1) two cement alkalinities (equivalent alkalinities of 0.32 and 1.08), 2) w/c 0.50 and 3) two rebar surface conditions (as-received and wire-brushed). Potential and macro-cell current between top and bottom bars were monitored to determine corrosion initiation time. Once corrosion was initiated, the specimen was ultimately autopsied to perform visual inspection, and the procedure included determination of the number and size of air voids along the top half of the upper steel surface. This size determination was based upon a diameter measurement assuming the air voids to be half spheres or ellipse. The followings were reached based upon the visual inspection of G109 specimens that were autopsied to date. First, voids at the steel-concrete interface facilitated passive film breakdown and onset of localized corrosion. Based upon this, the initiation mechanism probably involved a concentration cell with contiguous concrete coated and bare steel serving as cathodes and anodes, respectively. Second, the corrosion tended to initiate at relatively large voids. Third, specimens with wire-brushed steel had a lower number of voids at the interface for both cement alkalinities, suggesting that air voids preferentially formed on the rough as-received surface compared to the smooth wire brushed one.