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Journal of the Korea Concrete Institute

J Korea Inst. Struct. Maint. Insp.
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  • Korea Citation Index (KCI)

  1. ์ •ํšŒ์›,ํ•œ๋‚จ๋Œ€ํ•™๊ต ๊ฑด์„ค์‹œ์Šคํ…œ๊ณตํ•™๊ณผ ์„์‚ฌ๊ณผ์ •
  2. ์ข…์‹ ํšŒ์›,ํ•œ๋‚จ๋Œ€ํ•™๊ต ๊ฑด์„ค์‹œ์Šคํ…œ๊ณตํ•™๊ณผ ๊ต์ˆ˜, ๊ต์‹ ์ €์ž



๋ถ€์‹์˜ํ–ฅ์ธ์ž, ํ…๋˜, ๋ถ€์‹์ „๋ฅ˜, ์—ผ์†Œ-์ˆ˜์‚ฐํ™”์ด์˜จ ๋น„, ๋ถ€์‹๋Ÿ‰, ์†Œ์„ 
Corrosion influencing factor, Tendon, Corrosion density, [Cl-]/[OH-] ratio, Corrosion weight, Wire strand

1. ์„œ ๋ก 

์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ฌผ(RC: Reinforced Concrete)์€ ๊ณต๊ทน์„ ๊ฐ€์ง€๊ณ  ์žˆ์œผ๋ฉฐ, ์™ธ๋ถ€๋กœ๋ถ€ํ„ฐ ์ˆ˜๋ถ„ ๋ฐ ์—ผํ™”๋ฌผ ์ด์˜จ์˜ ์นจํˆฌ๋กœ ์ธํ•ด ๋ถ€์‹์ด ๋ฐœ์ƒํ•œ๋‹ค(Broomfield, 1997; Thomas and Bamforth, 1999). ๋งŽ์€ ์—ฐ๊ตฌ์—์„œ ์ž„๊ณ„ ๋ถ€์‹๋†๋„ ๋ฐ ํ—ˆ์šฉ์—ผํ™”๋ฌผ์— ๋Œ€ํ•œ ์ œ์•ˆ์ด ์žˆ์—ˆ์œผ๋ฉฐ, ์ด๋Ÿฌํ•œ ์—ฐ๊ตฌ๋Š” ๋งค์šฐ ๋ณด์ˆ˜์ ์œผ๋กœ ๊ฐ๊ตญ์˜ ์‹œ๋ฐฉ์„œ ๋ฐ ๊ตฌ์กฐ์„ค๊ณ„๊ธฐ์ค€์—์„œ ์ œ์•ˆ๋˜๊ณ  ์žˆ๋‹ค(EN206, 2013; JSCE, 2002; China, 2007).

1970๋…„๋Œ€ ์ดํ›„ PS ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ฌผ์ด ์ค€๊ณต๋˜๋ฉด์„œ ์†Œ์„ ์„ ๊ผฌ์•„์„œ ์—ฐ๊ฒฐ์‹œํ‚จ ํ…๋˜(Tendon)์ด ๋งŽ์ด ์‚ฌ์šฉ๋˜์—ˆ์œผ๋ฉฐ, ์ด๋Ÿฌํ•œ ๊ตฌ์กฐ๋ฌผ์—์„œ๋Š” ํฐ ์‘๋ ฅ์ด ์ด๋ฏธ ๋„์ž…๋˜์–ด ์žˆ์œผ๋ฏ€๋กœ ๋ถ€์‹์— ๋Œ€ํ•ด ๋”์šฑ ์ทจ์•ฝํ•˜๋‹ค. ์ด๋ฏธ ํฐ ์‘๋ ฅ์ด ๋„์ž…๋œ ์ƒํƒœ์—์„œ๋Š” ์†Œ์„ ์˜ ์ €ํ•ญ์ด ๊ฐ์†Œํ•˜๋ฏ€๋กœ ๊ฐ™์€ ๋ถ€์‹ํ™˜๊ฒฝ์—์„œ ์‘๋ ฅ์— ๋”ฐ๋ผ ๋ถ€์‹์ง„ํ–‰์€ ๋น ๋ฅด๊ฒŒ ๋‚˜ํƒ€๋‚˜๊ณ  ์žˆ๋‹ค(Saraswathy et al., 2018; Lee et al., 2017; Podolny., 1992). ๋˜ํ•œ ์ผ๋ฐ˜ RC ๊ตฌ์กฐ๋ฌผ์˜ ๋‹จ์ผ ์ฒ ๊ทผ์—์„œ ์ฃผ๋กœ ๋ฐœ์ƒํ•˜๋Š” Micro-cell์— ๊ธฐ๋ฐ˜ํ•œ ๊ณต์‹(Pitting)๋ณด๋‹ค Macro cell ๋˜๋Š” Crevice cell์—์„œ๋„ ๋ถ€์‹์ด ๋ฐœ์ƒํ•˜๊ฒŒ ๋œ๋‹ค(Lee et al., 2017; Permeh et al., 2016; Lee et al., 2022).

์ฝ˜ํฌ๋ฆฌํŠธ๋Š” ์‹œ๋ฉ˜ํŠธ๋ฅผ ๊ธฐ๋ฐ˜์œผ๋กœ ์ œ์กฐ๋˜๋ฏ€๋กœ ๋‚ด๋ถ€ ๋ถ€์‹์— ๋ฏธ์น˜๋Š” ์˜ํ–ฅ์ธ์ž๊ฐ€ ๋งค์šฐ ๋‹ค์–‘ํ•˜๋‹ค. ์ฝ˜ํฌ๋ฆฌํŠธ ๊ด€์ ์—์„œ๋Š” ๋‚ฎ์€ ๋ฌผ-์‹œ๋ฉ˜ํŠธ๋น„๋‚˜ ๋†’์€ ํ”ผ๋ณต๋‘๊ป˜๋ฅผ ์ด์šฉํ•˜์—ฌ ๊ณ ๋‚ด๊ตฌ์„ฑ ๊ตฌ์กฐ๋ฌผ์„ ์‹œ๊ณตํ•  ์ˆ˜ ์žˆ๋‹ค. ์ฆ‰ ํˆฌ์ˆ˜์„ฑ ๋ฐ ํ™•์‚ฐ์„ฑ์˜ ๊ฐ์†Œ๋ฅผ ํ†ตํ•˜์—ฌ ์—ผํ™”๋ฌผ ์ด์˜จ ํ™•์‚ฐ์„ ์ง€์—ฐ์‹œํ‚ค๋ฉฐ, ์ด๋กœ ์ธํ•ด ์ฒ ๊ทผ์œ„์น˜๊นŒ์ง€ ๋„๋‹ฌํ•˜๋Š” ์‹œ๊ฐ„์„ ์—ฐ์žฅํ•˜์—ฌ ๋‚ด๊ตฌ์ˆ˜๋ช…์„ ์ฆ๊ฐ€์‹œํ‚ค๊ฒŒ ๋œ๋‹ค (Kwon et al., 2009; Thomas and Bentz, 2002).

๋ฐ€์‹คํ•œ ๊ตฌ์กฐ์ฒด๋กœ ์ธํ•œ ๊ณต๊ทน๋ฅ ์˜ ๊ฐ์†Œ๋Š” ์ˆ˜๋ถ„ ๋ฐ ์—ผํ™”๋ฌผ์˜ ์ด๋™์„ ์ œ์–ดํ•˜๋Š” ๋ฐ ํšจ๊ณผ์ ์ด๋‹ค. ๋˜ํ•œ C3A ์–‘์˜ ์ฆ๊ฐ€๋กœ ์ธํ•œ ์—ผํ™”๋ฌผ ์ด์˜จ์˜ ํก์ฐฉ์˜ ์ฆ๊ฐ€(Oh et al., 1999; Rasheeduzzafar, 1992), ์‹œ๋ฉ˜ํŠธ ๋ฐ ํ˜ผํ™”์žฌ๋ฃŒ (๊ณ ๋กœ์Šฌ๋ž˜๊ทธ ๋ฏธ๋ถ„๋ง ๋˜๋Š” ํ”Œ๋ผ์ด์• ์‹œ)์— ๋”ฐ๋ผ ์ƒ์„ฑ๋˜๋Š” ์ˆ˜ํ™”๋ฌผ์— ํก์ฐฉ๋˜๋Š” ๊ณ ์ • ์—ผํ™”๋ฌผ๋Ÿ‰ ์ฆ๊ฐ€ ๋ฐ ํ™•์‚ฐ์„ฑ์˜ ๊ฐ์†Œ๊ฐ€ ์ฃผ๋œ ์—ผํ™”๋ฌผ์˜ ์ €ํ•ญ๊ธฐ๊ตฌ๊ฐ€ ๋œ๋‹ค(Yuan et al., 2009; Arya et al., 1990). ์ด๋Ÿฌํ•œ ์ž์œ  ๋ฐ ๊ณ ์ •์—ผํ™”๋ฌผ๋Ÿ‰๊ณผ์˜ ๊ด€๊ณ„๋Š” Isotherm ๊ด€๊ณ„๋กœ ์ •์˜๋˜์–ด ๋งŽ์€ ์—ฐ๊ตฌ๊ฐ€ ์ง„ํ–‰๋˜์–ด ์™”๋‹ค(Arya et al., 1990; Sandberg, 1999; Luping and Nilsson, 1993). ๋˜ํ•œ ์‹œ๋ฉ˜ํŠธ๋‚ด์˜ ๋งŽ์€ 1๊ฐ€ ์–‘์ด์˜จ๊ณผ ํ‰ํ˜•์„ ์ด๋ฃจ๋Š” ์ˆ˜์‚ฐํ™” ์ด์˜จ[OH-] ์–‘์€ pH์™€ ์ง์ ‘์ ์ธ ๊ด€๊ณ„๊ฐ€ ์žˆ์œผ๋ฉฐ, ์—ผํ™”๋ฌผ์ด์˜จ๊ณผ์˜ ์ƒ๋Œ€๋น„, ์ฆ‰ [Cl-]/[OH-]์— ๋”ฐ๋ฅธ ๋ถ€์‹๊ฑฐ๋™์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๊ฐ€ ์ง„ํ–‰๋˜์—ˆ๋‹ค. ํŠนํžˆ 0.3~0.6 ๋ชฐ ๋น„์œจ์„ ๊ฐ€์ง„ ์ˆ˜์šฉ์•ก์ƒ์—์„œ์˜ ์ฒ ๊ทผ๋ถ€์‹ ํŠน์„ฑ์€ ๋งŽ์€ ์—ฐ๊ตฌ์ž๋“ค์— ์˜ํ•ด ์—ฐ๊ตฌ๋˜์—ˆ๋‹ค(Oh et al., 1999; Thangavel and Rengaswamy, 1998; Gouda, 1970; DA, 1967).

์‹ค์ œ๋กœ ์ฝ˜ํฌ๋ฆฌํŠธ๋‚ด์˜ ์ฒ ๊ทผ๋ถ€์‹ ํ˜„์ƒ์€ ์‹œ๋ฉ˜ํŠธ์™€ ์—ฐ๊ณ„๋œ ํ™”ํ•™์กฐ์„ฑ ๋ฐ ์ˆ˜ํ™”๋ฐ˜์‘, ์ฝ˜ํฌ๋ฆฌํŠธ ์ œ์กฐ์‹œ์— ์‚ฌ์šฉ๋˜๋Š” ํ˜ผํ™”์žฌ๋ฃŒ์™€ ๊ด€๋ จ๋œ ํฌ์กธ๋ž€ ๋ฐ˜์‘, ํ”ผ๋ณต๋‘๊ป˜ ์ฆ๊ฐ์— ๋”ฐ๋ฅธ ๋ฌผ์งˆ ์ด๋™๋Ÿ‰์˜ ๋ณ€ํ™”, ์™ธ๋ถ€์˜ ํ™˜๊ฒฝ์— ๋”ฐ๋ฅธ ์ˆ˜๋ถ„ ๊ตฌ๋ฐฐ, ํ‘œ๋ฉด ์—ผํ™”๋ฌผ ์ด์˜จ์˜ ํ™•์‚ฐ ๋ฐ ์นจํˆฌ ๋“ฑ์˜ ๋ฉ”์ปค๋‹ˆ์ฆ˜์ด ๋งค์šฐ ๋ณต์žกํ•˜๊ฒŒ ์—ฐ๊ณ„๋˜์–ด ์žˆ๋‹ค.

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์ด‰์ง„์‹œํ—˜์„ ํ†ตํ•˜์—ฌ ๋ถ€์‹์˜ํ–ฅ์ธ์ž(์—ผํ™”๋ฌผ ์ด์˜จ ๋ฐ [Cl-]/[OH-])์— ๋”ฐ๋ฅธ ํ…๋˜์˜ ๋ถ€์‹๊ฒฝํ–ฅ์„ ํ‰๊ฐ€ํ•˜๋„๋ก ํ•œ๋‹ค. ์ด๋ฅผ ์œ„ํ•ด ์ค‘์š”ํ•œ ์˜ํ–ฅ์ธ์ž์ธ ์—ผํ™”๋ฌผ ๋†๋„์™€ [Cl-]/[OH-]์˜ ๋น„๋ฅผ ๊ณ ๋ คํ•˜์—ฌ ํ…๋˜์˜ ์†Œ์„ ์œ„์น˜๋ณ„ ๋ถ€์‹์ „๋ฅ˜๋ฅผ ์ธก์ •ํ•˜์˜€๋‹ค. ์ด‰์ง„๋ถ€์‹ํ™˜๊ฒฝ์„ ์กฐ์„ฑํ•˜๊ธฐ ์œ„ํ•ด ์ฝ˜ํฌ๋ฆฌํŠธ ๋Œ€์‹  ๋ชจ๋ž˜๋ฅผ ์‚ฌ์šฉํ•˜์˜€์œผ๋ฉฐ, ์ธก์ •์ฃผ๊ธฐ๋งˆ๋‹ค ์—ผ์ˆ˜ ์ฃผ์ž…์„ ํ†ตํ•ด ์Šต์œค ๋ชจ๋ž˜์ƒํƒœ ์กฐ์„ฑํ•˜์˜€๋‹ค. ๋˜ํ•œ ๊ณ ์ •๋œ ๋†’์ด์— ํ…๋˜์„ ๋ฐฐ์น˜ํ•˜๊ณ  ๊ฐ ์†Œ์„ ์„ Ag/AgCl ์ „๊ทน์„ ์‚ฌ์šฉํ•œ ๋ถ„๊ทน ์ €ํ•ญ ์žฅ๋น„์™€ ์—ฐ๊ฒฐํ•˜์—ฌ ๋ถ€์‹์ „๋ฅ˜๋ฅผ ์ธก์ •ํ•˜์˜€๋‹ค. ๋ถ€์‹์ด‰์ง„์„ ์œ„ํ•˜์—ฌ 3์ˆ˜์ค€์˜ ์—ผํ™”๋ฌผ ๋†๋„ ์™€ 3์ˆ˜์ค€์˜ [Cl-]/[OH-]๋น„๋ฅผ ๊ณ ๋ คํ•˜์˜€์œผ๋ฉฐ, ํ…๋˜์˜ ๋ถ€์‹์ „๋ฅ˜๋ฅผ ์ •๋Ÿ‰์ ์œผ๋กœ ํ‰๊ฐ€ํ•˜์˜€๋‹ค.

2. ์ฝ˜ํฌ๋ฆฌํŠธ ๋‚ด๋ถ€ ๋ณด๊ฐ•์žฌ์˜ ๋ถ€์‹๊ธฐ๊ตฌ

์—ผํ•ด๋Š” ์ฒ ๊ทผ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๋ถ€์‹์„ ์œ ๋ฐœํ•˜๊ณ  ๋‚ด๊ตฌ์„ฑ์„ ์ €ํ•ดํ•˜๋Š” ์ฃผ์š” ๋ฌธ์ œ ์ค‘ ํ•˜๋‚˜๋กœ ์ธ์‹๋˜๊ณ  ์žˆ๋‹ค. ์ผ๋ฐ˜์ ์ธ ์ฝ˜ํฌ๋ฆฌํŠธ ๋‚ด๋ถ€๋Š” pH 12.5~13์— ์ด๋ฅด๋Š” ๊ฐ•์•Œ์นผ๋ฆฌ ์ƒํƒœ๋ฅผ ์œ ์ง€ํ•˜๊ณ  ์žˆ์œผ๋ฉฐ, ์ฝ˜ํฌ๋ฆฌํŠธ ๋‚ด๋ถ€์— ๋งค๋ฆฝ๋œ ์ฒ ๊ทผ์˜ ํ‘œ๋ฉด์€ ๋ถ€๋™ํƒœํ”ผ๋ง‰(Passive film)์ด ํ˜•์„ฑ๋˜์–ด ๋ถ€์‹์œผ๋กœ๋ถ€ํ„ฐ ์•ˆ์ „ํ•œ ์ƒํƒœ์— ์žˆ๋‹ค๊ณ  ์•Œ๋ ค์ ธ ์žˆ๋‹ค. ๋ถ€๋™ํƒœํ”ผ๋ง‰์€ ์ˆ˜ํ™”์‚ฐํ™”๋ฌผ๋กœ ์ด๋ฃจ์–ด์ง„ ์–‡์€ ์‚ฐํ™” ํ”ผ๋ง‰์œผ๋กœ, ์ฒ ๊ทผ์˜ ๋ถ€์‹์„ ์–ต์ œํ•˜๊ณ  ๊ฐ•์•Œ์นผ๋ฆฌ ํ™˜๊ฒฝ์ด ์ง€์†๋  ๊ฒฝ์šฐ, ๋ถˆํ™œ์„ฑ ์ƒํƒœ๊ฐ€ ๋˜์–ด ์ด์˜จ ๊ตํ™˜์„ ์–ต์ œํ•œ๋‹ค(Broomfield, 1997).

๊ทธ๋Ÿฌ๋‚˜ ์ˆ˜ํ™”๋ฌผ์˜ ์นจ์ถœ์— ๋”ฐ๋ฅธ pH์˜ ๊ฐ์†Œ, ๊ทธ๋ฆฌ๊ณ  ์Œ์ด์˜จ์˜ ์นจํˆฌ๋ฅผ ํ†ตํ•ด ์ฒ ๊ทผ์˜ ๋ถ€์‹ํ˜„์ƒ์ด ๋ฐœ์ƒํ•  ์ˆ˜ ์žˆ์œผ๋ฉฐ, ํŠนํžˆ ์Œ์ด์˜จ ์ค‘ ์—ผํ™”๋ฌผ ์ด์˜จ(Cl-)์€ ๋†’์€ ํ™œ์„ฑ๋„๋กœ ์ธํ•ด ๋ถ€์‹์„ ๊ฐ€์†ํ™”ํ•˜๋Š” ๋ถ€์‹์˜ํ–ฅ์ธ์ž๋กœ ์•Œ๋ ค์ ธ ์žˆ๋‹ค. ์ฒ ๊ทผ ๋ถ€์‹์˜ ์‚ฐํ™” ๋ฐ ํ™˜์› ๋ฐ˜์‘์€ ์‹ (1), (2), (3)๊ณผ ๊ฐ™์ด ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค(Lee and Zielske, 2014).

(1)
$Fe\to Fe^{2+}+2e^{-}(Anodic\; reaction)$
(2)
$H_{2}O+1/2O_{2}+2e^{-}\to 2(OH)^{-}(Cathodic\; reaction)$
(3)
$Fe+1/2O_{2}+H_{2}O\to Fe(OH)_{2}(Overall\; reaction)$

์ฒ ๊ทผ์˜ ๋ถ€์‹์ด ์ง„ํ–‰๋˜๋ฉด์„œ ์ƒ๊ธด ๋…น(Rust)์€ ์ˆ˜๋ถ„๊ณต๊ธ‰์œผ๋กœ ์ธํ•ด 2~6 ๋ฐฐ๋กœ ํŒฝ์ฐฝํ•˜์—ฌ ์ฒ ๊ทผ์˜ ๊ท ์—ด์„ ์œ ๋ฐœํ•œ๋‹ค. ์ด๋Ÿฌํ•œ ๊ท ์—ด๋กœ ์ธํ•ด ์‚ฐ์†Œ์™€ ์ˆ˜๋ถ„์ด ์‰ฝ๊ฒŒ ์นจํˆฌํ•  ์ˆ˜ ์žˆ๋Š” ํ™˜๊ฒฝ์ด ์กฐ์„ฑ๋˜๋ฉฐ, ์ดํ›„ ์Šฌ๋ฆฝํ˜„์ƒ์ด ๋ฐœ์ƒํ•˜์—ฌ ๊ตฌ์กฐ๋ฌผ์˜ ๊ธฐ๋Œ€์ˆ˜๋ช…์„ ๋‹จ์ถ•์‹œํ‚จ๋‹ค(Broomfield, 1997; Saraswathy et al., 2018).

Fig. 1์—์„œ๋Š” ์—ผํ™”๋ฌผ์ด์˜จ ๋ฐ ์ˆ˜๋ถ„์นจํˆฌ์— ๋”ฐ๋ฅธ ์ฒ ๊ทผ ๋ถ€์‹๊ธฐ๊ตฌ๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

Fig. 1 Corrosion mechanism through chloride ion penetration
../../Resources/ksm/jksmi.2024.28.4.21/fig1.png

3. ์ด‰์ง„๋ถ€์‹ํ™˜๊ฒฝ ๋ฐ ์‹คํ—˜๊ณ„ํš

3.1 ์‚ฌ์šฉ์žฌ๋ฃŒ

๋ณธ ์‹คํ—˜์—์„œ๋Š” ๋ถ€์‹์ „๋ฅ˜ ํ‰๊ฐ€๋ฅผ ์œ„ํ•ด 3์ˆ˜์ค€์˜ ์—ผํ™”๋ฌผ ๋†๋„(0.0, 0.125, 0.25mol/l)์™€ 3์ˆ˜์ค€์˜ [Cl-]/[OH-]๋น„๋ฅผ ๋ถ€์‹ ์˜ํ–ฅ ์ธ์ž๋กœ ๊ณ ๋ คํ•˜์˜€๋‹ค. ์—ผํ™”๋ฌผ ๋†๋„ 0.125mol/l์— ๋Œ€ํ•ด์„œ NaOH๋ฅผ ์ฒจ๊ฐ€ํ•˜์—ฌ 3์ˆ˜์ค€(0.3, 0.6, 0.9)์˜ [Cl-]/[OH-] ๋น„๋ฅผ ์ค€๋น„ํ•˜์—ฌ ์ด‰์ง„ ๋ถ€์‹ ์‹คํ—˜์— ์‚ฌ์šฉํ•˜์˜€๋‹ค.

์‹คํ—˜ ์‹œํŽธ์€ 300 ร— 300 ร— 200mm ํฌ๊ธฐ์˜ ์ง์œก๋ฉด์ฒด ์•„ํฌ๋ฆด๋ฐ•์Šค๋กœ ์„ค๊ณ„ํ•˜์˜€๋‹ค. ์ฝ˜ํฌ๋ฆฌํŠธ ๋Œ€์‹  ์ฒด๊ฐ€๋ฆ„ ์‹œํ—˜(KS F 2502)์„ ํ†ตํ•ด 4.75mm์ฒด๋ฅผ ํ†ต๊ณผํ•œ ์ž”๊ณจ์žฌ๋ฅผ ์‚ฌ์šฉํ•˜์˜€์œผ๋ฉฐ, ์ด‰์ง„๋ถ€์‹์‹œํ—˜์„ ํ†ตํ•ด ๋ถ€์‹ ๋ชจ๋‹ˆํ„ฐ๋ง์„ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ์‚ฌ์šฉ๋œ ์ž”๊ณจ์žฌ์˜ ๋น„์ค‘ ๋ฐ ํก์ˆ˜์œจ์€ ๊ฐ๊ฐ 3.2 %์™€ 2.8 %๋กœ ํ‰๊ฐ€๋˜์—ˆ์œผ๋ฉฐ, ํ‘œ์ค€ ์ง€๋ฆ„ 12.7mm, ๊ธธ์ด 200mm๋ฅผ ๊ณ ๋ คํ•œ ํ…๋˜(KS D 7002 B type, SWPC 7B)์„ ๋งค๋ฆฝํ•˜์˜€๋‹ค. 6๊ฐœ์˜ ์†Œ์„ ์ค‘ ๋ฐ”๊นฅ์ชฝ์œผ๋กœ ๋‘˜๋Ÿฌ์‹ธ์ธ ์†Œ์„  4๊ฐœ์— ์ „์„ ์„ ์—ฐ๊ฒฐํ•˜์˜€์œผ๋ฉฐ, ๋ถ€์‹์ „๋ฅ˜ ์ธก์ •์‹œ ๊ฐ ์†Œ์„ ์—์„œ ์ธก์ •๋œ ๊ฐ’์˜ 4๊ฐœ์˜ ํ‰๊ท ๊ฐ’์„ ์‚ฌ์šฉํ•˜์˜€๋‹ค.

Fig. 2์™€ Fig. 3์— ๊ฐ๊ฐ ์‹œํŽธ์˜ ๋ชจ์‹๋„์™€ ์‹œํŽธ ๋ฐ ํ…๋˜์˜ ์ „๊ฒฝ์„ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

Fig. 2 Schematic diagram for test sample
../../Resources/ksm/jksmi.2024.28.4.21/fig2.png
Fig. 3 Photos of test sample and corroded tendons
../../Resources/ksm/jksmi.2024.28.4.21/fig3-1.png../../Resources/ksm/jksmi.2024.28.4.21/fig3-2.png

3.2 ์ธก์ •์žฅ๋น„

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” Ag/AgCI ์ „๊ทน์„ ์‚ฌ์šฉํ•˜๋Š” GAITEC ์žฅ๋น„๋ฅผ ํ™œ์šฉํ•˜์—ฌ ์ด‰์ง„๋ถ€์‹ํ™˜๊ฒฝ์—์„œ์˜ ๋ถ€์‹ ์ „๋ฅ˜๋ฅผ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ์‚ฌ์šฉ ์žฅ๋น„๋Š” ASTM C 876 ํ‘œ์ค€์— ์ค€ํ•˜์—ฌ ๋ถ€์ฐฉ๋œ 4๊ฐœ์˜ ์ „๊ทน์œผ๋กœ ์‹œํŽธ ํ‘œ๋ฉด์—์„œ ํ…๋˜์˜ ์ „๊ธฐ์  ๋ฐ˜์‘์„ ๊ณ ๋ คํ•˜๋Š” ๊ธฐ์ˆ ์ด๋‹ค. ์™ธ๋ถ€์—์„œ ์ธก์ •๋œ ์ „์••์„ ํ†ตํ•ด ์ฒ ๊ทผ์˜ ์ €์ฃผํŒŒ ์ž„ํ”ผ๋˜์Šค ๋ฐ˜์‘์„ ๊ณ ๋ คํ•œ ๋ถ€์‹์ „๋ฅ˜๋ฅผ ์ธก์ •ํ•˜๋ฉฐ, Fig. 4์— ๋ถ€์‹์ „์œ„ ํ‰๊ฐ€๋ฅผ ์œ„ํ•œ ๋ฐ˜์‘ ๊ธฐ๊ตฌ ๋ฐ ์žฅ๋น„๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ๋˜ํ•œ ์žฅ๋น„์— ์‚ฌ์šฉ๋œ ์ธก์ • ์ „๊ทน์˜ ๋ถ€์‹์ „๋ฅ˜์™€ ๋ถ€์‹์ƒํƒœ ๊ฒฐ๊ณผ๋Š” Table 1์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

Fig. 4 Mechanism for corrosion equipment
../../Resources/ksm/jksmi.2024.28.4.21/fig4-1.png../../Resources/ksm/jksmi.2024.28.4.21/fig4-2.png
Table 1 Suggestion of corrosion density(ASTM C 876-09, 2009)

Corrosion density

Classification

( $\mu$A/cm2)

( $\mu$m/year)

Less 0.1

Less 10

Passive/Low

0.1 - 1

10 - 30

Moderate

1 - 10

30 - 100

High

Over 10

Over 100

Severe

์‚ฌ์šฉ๋œ ์ธก์ • ์žฅ๋น„๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ๋ฅผ ๋Œ€์ƒ์œผ๋กœ ์ธก์ •ํ•˜๋Š” ์žฅ๋น„์ด์ง€๋งŒ, ๋ณธ ์‹คํ—˜์—์„œ๋Š” ๋งค๋ฆฝ๋œ ํ…๋˜์˜ ๋ถ€์‹ ์—ฌ๋ถ€๋ฅผ ์œก์•ˆ์œผ๋กœ ๊ด€์ฐฐํ•˜๊ณ  ํ…๋˜์˜ ์ค‘๋Ÿ‰ ๊ฐ์†Œ์œจ์„ ํ‰๊ฐ€ํ•˜๊ธฐ ์œ„ํ•ด ์ฝ˜ํฌ๋ฆฌํŠธ ๋Œ€์‹  ์ž”๊ณจ์žฌ๋ฅผ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ์ฝ˜ํฌ๋ฆฌํŠธ๋ฅผ ์‚ฌ์šฉํ•  ๊ฒฝ์šฐ, ์ •ํ™•ํ•œ ์‹คํ—˜ํ™˜๊ฒฝ์„ ์žฌํ˜„ํ•˜๊ธฐ ์–ด๋ ต๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค. ๋˜ํ•œ ์‹คํ—˜์˜ ์ •ํ™•์„ฑ์„ ๋†’์ด๊ธฐ ์œ„ํ•ด ํ•จ์ˆ˜์œจ์„ ๋™์ผํ•œ ํ™˜๊ฒฝ ์กฐ๊ฑด์œผ๋กœ ์กฐ์„ฑํ•˜์˜€์œผ๋ฉฐ, ์—ผ์ˆ˜ ์ฃผ์ž…์„ ํ†ตํ•ด ์Šต์œค ์ƒํƒœ๋ฅผ ์œ ์ง€ํ•˜์˜€๋‹ค.

3.3 ์ด‰์ง„๋ถ€์‹ํ™˜๊ฒฝ์— ๋”ฐ๋ฅธ ๋ถ€์‹ ๋ชจ๋‹ˆํ„ฐ๋ง

3 ์ˆ˜์ค€์˜ ์—ผํ™”๋ฌผ ๋†๋„์™€ 3์ˆ˜์ค€์˜ [Cl-]/[OH-]๋น„๋ฅผ ๊ณ ๋ คํ•œ ์žฅ๊ธฐ ๋ถ€์‹ ๋ชจ๋‹ˆํ„ฐ๋ง์„ ์œ„ํ•˜์—ฌ ์‹คํ—˜๊ธฐ๊ฐ„์€ ์ด 28์ฃผ๋กœ ๊ณ„ํšํ•˜์˜€์œผ๋ฉฐ, 2์ฃผ ๊ฐ„๊ฒฉ์œผ๋กœ Ag/AgCl ์ „๊ทน์„ ๊ฐ€์ง„ ์žฅ๋น„๋ฅผ ํ†ตํ•ด ๋ถ€์‹ ์ „๋ฅ˜๋ฅผ ์ธก์ •ํ•˜์˜€๋‹ค. ์ดํ›„ ์‹œํŽธ ์ƒ๋ถ€์—์„œ๋ถ€ํ„ฐ ์—ผํ™”๋ฌผ์„ ์ฃผ์ž…ํ•˜์—ฌ ์ด‰์ง„๋ถ€์‹ํ™˜๊ฒฝ์„ ์กฐ์„ฑํ•˜์˜€์œผ๋ฉฐ, ์ธก์ •์ฃผ๊ธฐ์— ๋Œ€ํ•œ ๋ชจ์‹๋„๋ฅผ Fig. 5์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

๋˜ํ•œ ๋ถ€์‹์„ ์ด‰์ง„์‹œํ‚ค๊ธฐ ์œ„ํ•ด ๋ชจ๋‹ˆํ„ฐ๋ง ๊ธฐ๊ฐ„ ๋™์•ˆ 2๊ฐ€์ง€ ์กฐ๊ฑด(๋ถ€๋ถ„ํฌํ™”์ƒํƒœ, ํฌํ™”์ƒํƒœ)์„ ์ถ”๊ฐ€์ ์œผ๋กœ ๊ณ ๋ คํ•˜์˜€๋‹ค. 16์ฃผ์ฐจ ๊นŒ์ง€๋Š” ์‹œํŽธ์˜ ์ƒํƒœ๋ฅผ ๋ถ€๋ถ„ํฌํ™”์ƒํƒœ๋กœ ์œ ์ง€ํ•˜์˜€์œผ๋ฉฐ, ์ดํ›„ ๋ถ€์‹ ๋ชจ๋‹ˆํ„ฐ๋ง์ด ์ข…๋ฃŒ๋˜๋Š” 28์ฃผ๊นŒ์ง€ ํฌํ™” ์ƒํƒœ๋ฅผ ์œ ์ง€ํ•˜์˜€๋‹ค. ๋ถ€์‹์œผ๋กœ ์ธํ•œ ๊ฐ์†Œ๋œ ํ…๋˜์˜ ๋ถ€์‹์ค‘๋Ÿ‰์„ ํ‰๊ฐ€ํ•˜๊ธฐ ์œ„ํ•˜์—ฌ 16์ฃผ์ฐจ์™€ 28์ฃผ์ฐจ์— ๋งค๋ฆฝ๋œ ํ…๋˜์„ ํšŒ์ˆ˜ํ•˜์—ฌ ์ „์ฒด ์ค‘๋Ÿ‰์„ ์ธก์ •ํ•˜์˜€์œผ๋ฉฐ, ๋ถ€์‹์ค‘๋Ÿ‰ ์ธก์ • ํ›„, ๊ฐ™์€ ์œ„์น˜์— ์กด์น˜ํ•˜์˜€๋‹ค. ๋ถ€์‹ ๋ชจ๋‹ˆํ„ฐ๋ง ๊ธฐ๊ฐ„ ๋™์•ˆ ์‹คํ—˜์‹ค ์˜จ๋„ ๋ฐ ์Šต๋„๋Š” Fig. 6๊ณผ ๊ฐ™๋‹ค.

Fig. 5 Schematic diagram for corrosion monitoring
../../Resources/ksm/jksmi.2024.28.4.21/fig5.png
Fig. 6 Environmental conditions (Temp. and R.H.)
../../Resources/ksm/jksmi.2024.28.4.21/fig6.png

4. ํ™˜๊ฒฝ์กฐ๊ฑด์— ๋”ฐ๋ฅธ ๋ถ€์‹์ „๋ฅ˜ ํŠน์„ฑ ๋ฐ ํ…๋˜ ๋ถ€์‹๋ฅ  ๋ณ€ํ™”

4.1 ์—ผํ™”๋ฌผ ๋†๋„์— ๋”ฐ๋ฅธ ๋ถ€์‹์ „๋ฅ˜ ๋ณ€ํ™”

๋ถ€์‹์ „๋ฅ˜์˜ ๊ฒฝ์šฐ ๋ถ€์‹ ๋ชจ๋‹ˆํ„ฐ๋ง ๊ธฐ๊ฐ„์— ๋”ฐ๋ผ ๋ชจ๋“  ์ˆ˜์ค€์—์„œ โ€˜Highโ€™์ˆ˜์ค€์˜ ๋ถ€์‹์†๋„๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ์œผ๋ฉฐ, Fig. 7์— ๋ถ€์‹์ „๋ฅ˜ ์ธก์ •๊ฒฐ๊ณผ๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ๋˜ํ•œ Fig. 7์—์„œ๋Š” ์‹คํ—˜์˜จ๋„๊ฒฐ๊ณผ๋ฅผ ๊ฐ™์ด ๋„์‹œํ•˜์˜€์œผ๋ฉฐ, ์ ์„ ์˜ ๊ฒฝ์šฐ 3.2์ ˆ์— ๋‚˜ํƒ€๋‚ธ ์ „๊ทน์˜ ๋ถ€์‹์ „๋ฅ˜ ์ƒํƒœ์—์„œ โ€˜Highโ€™ ์กฐ๊ฑด์˜ ์ƒํ•œ์น˜(10 ฮผA/cm2)๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค.

๋ถ€์‹์ „๋ฅ˜๋Š” ์†Œ์„ ๊ณผ์˜ ์ ‘์ด‰๋ฉด ๋ฐ ๋ฐœ์ƒํ•œ ๋ถ€์‹์˜ ์˜ํ–ฅ์œผ๋กœ ๋ณ€๋™์„ฑ์ด ํฌ๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ๋˜ํ•œ ์˜จ๋„๊ฐ€ ๋‚ฎ์•„์ง€๋Š” ์‹œ์ ์—์„œ 0.125mol/l ๋ฐ 0.25mol/l์—์„œ ๋ถ€์‹์ „๋ฅ˜๊ฐ€ ๋‚ฎ์•„์ง€๊ณ  ์žˆ์Œ์„ ์•Œ ์ˆ˜ ์žˆ์œผ๋ฉฐ, ์—ผํ™”๋ฌผ์˜ ๋†๋„๊ฐ€ ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ๋†’์€ ๋ถ€์‹์ „๋ฅ˜๋ฅผ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ๋‹ค. ๊ฐ ์ธก์ •์ฃผ๊ธฐ๋งˆ๋‹ค ๋ถ€์‹์ „๋ฅ˜์˜ ๋ณ€๋™์„ฑ์ด ์žˆ์ง€๋งŒ, ์—ผํ™”๋ฌผ ๋†๋„๊ฐ€ 0.125mol/l์ด์ƒ์—์„œ๋Š” ๋ถ€์‹์ „๋ฅ˜๊ฐ€ ๋šœ๋ ทํ•œ ์ฆ๊ฐ€๋ฅผ ํ™•์ธํ•  ์ˆ˜ ์—†์—ˆ๋Š”๋ฐ, 0.125mol/l์กฐ๊ฑด์€ ๋ถ€์‹์ด ํ™œ์„ฑ๋„๊ฐ€ ํฌํ™”๋˜๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค.

Fig. 8 Average corrosion density with different chloride concentration
../../Resources/ksm/jksmi.2024.28.4.21/fig8.png
Fig. 7 Corrosion density with temperature
../../Resources/ksm/jksmi.2024.28.4.21/fig7.png

Fig. 8์—์„œ๋Š” ๊ฐ ์กฐ๊ฑด์— ๋”ฐ๋ผ ์ธก์ •๋œ ๋ถ€์‹์ „๋ฅ˜์˜ ํ‰๊ท ์„ ๋‚˜ํƒ€๋‚ด์—ˆ์œผ๋ฉฐ, ๊ฐ ์—ผํ™”๋ฌผ ๋†๋„์— ๋”ฐ๋ฅธ ๋ถ€์‹์ „๋ฅ˜ ํ‰๊ท ๊ฐ’์„ ์—ฐ๊ฒฐํ•˜์—ฌ ๋ถ€์‹์ „๋ฅ˜์˜ ๊ฑฐ๋™์„ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ๋ถ€์‹ ๋ชจ๋‹ˆํ„ฐ๋ง ๊ธฐ๊ฐ„๋™์•ˆ ์ธก์ •๋œ ๋ถ€์‹์ „๋ฅ˜์˜ ํ‰๊ท ๊ฐ’์€ 0.0mol/l, 0.125mol/l, 0.25mol/l์—์„œ ๊ฐ๊ฐ 5.13ฮผA/cm2, 17.53ฮผA/cm2, 20.07ฮผA/cm2๋กœ ํ‰๊ฐ€๋˜์—ˆ์œผ๋ฉฐ, ์ด๋Š” ์ดˆ๊ธฐ ์กฐ๊ฑด์—์„œ ์—ผํ™”๋ฌผ ๋†๋„๊ฐ€ ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ๋ถ€์‹์ „๋ฅ˜๊ฐ€ ์ฆ๊ฐ€ํ•จ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. ์˜จ๋„๊ฐ€ ๋‚ฎ์€ ๊ฒฝ์šฐ ๋ถ€์‹๊ฑฐ๋™์€ ๊ฐ์†Œํ•˜๋Š”๋ฐ(Yoon and Kwon, 2022), ํ…๋˜์˜ ๊ฒฝ์šฐ, ์†Œ์„ ๊ฐ„์˜ ์ ‘์ด‰๋ฉด์˜ ๋ถˆ๊ท ์ผ์„ฑ๊ณผ ์ด ์—ฐ๊ฒฐ๋˜์–ด ์žˆ์œผ๋ฉฐ, ์†Œ์„ ์‚ฌ์ด์„œ ๋ฐœ์ƒํ•œ ๋ถ€์‹์˜ํ–ฅ์œผ๋กœ ๋ณ€๋™์„ฑ์ด ํฌ๊ฒŒ ํ‰๊ฐ€๋˜์—ˆ๋‹ค.

4.2 [Cl-]/[OH-] ๋†๋„๋น„์— ๋”ฐ๋ฅธ ๋ถ€์‹์ „๋ฅ˜ ๋ณ€ํ™”

๋ณธ ์ ˆ์—์„œ๋Š” 0.125mol/l์กฐ๊ฑด์—์„œ 3์ˆ˜์ค€์˜ [Cl-]/[OH-]๋น„๋ฅผ ๊ณ ๋ คํ•˜์—ฌ ๋ถ€์‹์ „๋ฅ˜์˜ ๊ฑฐ๋™์„ ๋ถ„์„ํ•˜์˜€๋‹ค.

0.125mol/l ์กฐ๊ฑด์—์„œ ์ธก์ •๋œ pH๊ฐ’์€ 8.02๋กœ ์ค‘์„ฑ์„ ๋‚˜ํƒ€๋‚ด์—ˆ์ง€๋งŒ, ๋™์ผํ•œ ์—ผํ™”๋ฌผ ๋†๋„์—์„œ NaOH๋ฅผ ๋ณ€ํ™”์‹œํ‚ค๋ฉด์„œ [Cl-]/[OH-]๋น„๋ฅผ 0.1~0.9๋กœ ๋ณ€ํ™”์‹œํ‚ฌ ๊ฒฝ์šฐ, pH๋Š” ํฌ๊ฒŒ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ๋ชฐ๋น„๊ฐ€ 0.1์ธ ๊ฒฝ์šฐ์—๋„ 12.9 ์ด์ƒ์˜ ๋†’์€ ์•Œ์นผ๋ฆฌ๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ์œผ๋ฉฐ, ๊ฒฐ๊ณผ๋ฅผ Fig. 9์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. NaOH๋ฅผ ๋„ฃ์ง€ ์•Š์€ ๊ฒฝ์šฐ (0.125mol/l)๋ฅผ ์ฐธ๊ณ ๊ฐ’์œผ๋กœ ํ•˜์—ฌ, ๋ชฐ๋น„์— ๋”ฐ๋ฅธ ๋ถ€์‹์ „๋ฅ˜๊ฐ’์„ Fig. 10์— ๋‚˜ํƒ€๋‚ด์—ˆ์œผ๋ฉฐ, ๋ถ€์‹ ์ „๋ฅ˜์˜ ํ‰๊ท ๊ฐ’์˜ ๋ณ€ํ™”๋ฅผ Fig. 11์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

Fig. 11์—์„œ ์•Œ ์ˆ˜ ์žˆ๋“ฏ์ด, [OH-] ๋†๋„๊ฐ€ ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ๋ถ€์‹์ „๋ฅ˜๋Š” ์ง€์†์ ์œผ๋กœ ๊ฐ์†Œํ•˜์˜€๋Š”๋ฐ, ๋ถ€์‹์„ ์•ผ๊ธฐํ•˜๋Š” ๋†’์€ ๋†๋„(0.125mol/l)์—์„œ๋„ [OH-]์˜ ์ฆ๊ฐ€๋Š” ํšจ๊ณผ์ ์ž„์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. [Cl-]/[OH-] 0.9์„ ์ œ์™ธํ•œ 2์ˆ˜์ค€์˜ ๋น„์œจ(0.6 ๋ฐ 0.3)์—์„œ ๊ธฐ์ค€ ์กฐ๊ฑด์ธ 0.125mol/l๋ณด๋‹ค ๋‚ฎ์€ ๋ถ€์‹ ์ „๋ฅ˜๊ฐ€ ์ธก์ •๋˜์—ˆ์œผ๋ฉฐ, [OH-]๋น„์˜ ๋†๋„๊ฐ€ ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ๋ถ€์‹์†๋„๊ฐ€ ์ง€์—ฐ๋˜์—ˆ๋‹ค.

๊ธฐ์กด์˜ ์—ฐ๊ตฌ์—์„œ๋Š” ๋ชฐ๋น„๊ฐ€ 0.9 ์ดํ•˜์ผ ๊ฒฝ์šฐ ์ˆ˜์šฉ์•ก ์ƒํƒœ์—์„œ ๋ถ€๋™ํƒœ ์˜์—ญ์œผ๋กœ ์ „ํ™˜๋˜์–ด, [Cl-]/[OH-]์ด ๋‚ฎ์„์ˆ˜๋ก ๋ถ€์‹์ „๋ฅ˜๊ฐ€ ์„ ํ˜•์ ์œผ๋กœ ๊ฐ์†Œํ•˜์˜€๋‹ค(Thangavel and Rengaswamy, 1998).

Fig. 9 Variation of pH with [Cl-]/[OH-]
../../Resources/ksm/jksmi.2024.28.4.21/fig9.png
Fig. 10 Corrosion density with different [Cl-]/[OH-] ratios
../../Resources/ksm/jksmi.2024.28.4.21/fig10.png
Fig. 11 Changes in average corrosion density with different [Cl-]/ [OH-] ratios
../../Resources/ksm/jksmi.2024.28.4.21/fig11.png

4.3 ๋†๋„์— ๋”ฐ๋ฅธ ํ…๋˜์˜ ๋ถ€์‹์ค‘๋Ÿ‰ ๋ณ€ํ™”

ํ…๋˜์˜ ๋ถ€์‹ ์ค‘๋Ÿ‰ ํ‰๊ฐ€ ๊ฒฐ๊ณผ ์—ผํ™”๋ฌผ ๋†๋„๊ฐ€ ๋†’์•„์งˆ์ˆ˜๋ก, [OH-]๋น„๊ฐ€ ๋‚ฎ์„์ˆ˜๋ก ๋ถ€์‹๋ฅ ์ด ๋†’๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค. Fig. 12๋Š” ๋‹ค์–‘ํ•œ ๋†๋„ ์กฐ๊ฑด์—์„œ ๋งค๋ฆฝ๋œ ํ…๋˜์˜ ๋ถ€์‹๋ฅ ์„ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ์—ผํ™”๋ฌผ ๋†๋„์— ๋”ฐ๋ผ, 0mol/l์—์„œ๋Š” 4.33wt/%, 0.125mol/l์—์„œ๋Š” 4.55wt/%, ๊ทธ๋ฆฌ๊ณ  0.25mol/l์—์„œ๋Š” 5.76wt/%์˜ ์ค‘๋Ÿ‰ ๊ฐ์†Œ๊ฐ€ ํ‰๊ฐ€๋˜์—ˆ์œผ๋ฉฐ, ์ด‰์ง„ ๊ธฐ๊ฐ„์— ์„ ํ˜•์ ์ธ ๊ด€๊ณ„๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ๋˜ํ•œ [Cl-]/[OH-] ๋น„์— ๋”ฐ๋ฅธ ์ค‘๋Ÿ‰ ๋ถ€์‹๋ฅ ์€ 0.9, 0.6, 0.3 ๋น„์œจ์—์„œ ๊ฐ๊ฐ 2.88wt/%, 2.43wt/%, 2.53wt/%๋กœ ์ธก์ •๋˜์—ˆ๋‹ค. ์ด๋Š” [OH-] ๋น„๊ฐ€ ๋†’์„์ˆ˜๋ก ํ…๋˜์˜ ๋ถ€์‹์ „๋ฅ˜๊ฐ€ ๊ฐ์†Œํ•จ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค.

Fig. 13์—์„œ๋Š” 0.0mol/l ์™€ 0.25mol/l์˜ ๋ถ€์‹์ƒํƒœ๋ฅผ 3D ์Šค์บ๋„ˆ๋กœ ์ธก์ •ํ•œ ์‚ฌ์ง„์„ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

Fig. 12 Corrosion reduction ratio in tendon
../../Resources/ksm/jksmi.2024.28.4.21/fig12.png
Fig. 13 Corrosion condition in tendon (3D photo)
../../Resources/ksm/jksmi.2024.28.4.21/fig13.png

4.4 ์˜ํ–ฅ์ธ์ž์™€ ๋ถ€์‹์ „๋ฅ˜์™€์˜ ์ƒ๊ด€์„ฑ

4.2์ ˆ์—์˜ Fig. 8์—์„œ๋Š” ์—ผํ™”๋ฌผ ๋†๋„์— ๋”ฐ๋ฅธ ๋ถ€์‹์ „๋ฅ˜์˜ ๋ณ€ํ™”๋ฅผ, Fig. 11์—์„œ๋Š” ์—ผ์†Œ-์ˆ˜์‚ฐํ™” ์ด์˜จ๋น„์— ๋”ฐ๋ฅธ ๋ถ€์‹์ „๋ฅ˜์˜ ๋ณ€ํ™”๋ฅผ ๋ถ„์„ํ•˜์˜€๋Š”๋ฐ, ์†Œ์„ ๊ฐ„์˜ ์ ‘์ด‰ ๋ฐ ๊ตญ๋ถ€ ๋ถ€์‹์˜ ์˜ํ–ฅ์œผ๋กœ ๋ณ€๋™์„ฑ์ด ๋งค์šฐ ํฐ ๊ฐ’๋“ค์ด ์ธก์ •๋˜์—ˆ๋‹ค. ๊ฐ ์‹คํ—˜๊ฐ’์˜ ์ตœ๋Œ€๊ฐ’์œผ๋กœ ์—ผํ™”๋ฌผ ๋†๋„๋ฅผ ๋‚˜๋ˆ„์–ด ์ •๊ทœํ™”ํ•˜์—ฌ ๊ฐ ํ‰๊ท ๊ฐ’์˜ ๋ณ€ํ™”๋งŒ์„ ๊ณ ๋ คํ•  ์ˆ˜ ์žˆ๋‹ค. ์ด ๊ฒฐ๊ณผ๋ฅผ Fig. 14์™€ ๊ฐ™์ด ๊ฒฐ๊ณผ๋ฅผ ๋„์‹œํ•˜์˜€๋‹ค.

Fig. 14์—์„œ ์•Œ ์ˆ˜ ์žˆ๋“ฏ์ด, ์‹คํ—˜๊ฐ’์˜ 50 %(์—ผํ™”๋ฌผ ๋†๋„ 0.125mol/l)์ด์ƒ์—์„œ๋Š” ํฐ ๋ถ€์‹์ „๋ฅ˜์˜ ๋ณ€ํ™”๋Š” ๋ถ„์„๋˜์ง€ ์•Š์•˜์œผ๋ฉฐ ๊ทธ ์ดํ•˜์˜ ๊ฐ’์—์„œ๋Š” ๋งค์šฐ ๋น ๋ฅธ 1.235์˜ ๊ธฐ์šธ๊ธฐ๊ฐ€ ํ‰๊ฐ€๋˜์—ˆ๋‹ค. [Cl-]/[OH-]์˜ ๋ณ€ํ™”์— ๋”ฐ๋ฅธ ๋ถ€์‹ ์ „๋ฅ˜ ๊ธฐ์šธ๊ธฐ๋Š” 0.351 ๊ณผ 0.170์œผ๋กœ ํ‰๊ฐ€๋˜์–ด ์—ผํ™”๋ฌผ ๋†๋„์— ๋”ฐ๋ฅธ ๋ถ€์‹์˜ํ–ฅ๋ณด๋‹ค๋Š” ๋‚ฎ์€ ๋ถ€์‹์ „๋ฅ˜ ๊ธฐ์šธ๊ธฐ๊ฐ€ ํ‰๊ฐ€๋˜์—ˆ๋‹ค. ์ด๋Š” ์ „์ˆ ํ•œ๋Œ€๋กœ 0.125mol/l์˜ ๋†’์€ ์—ผํ™”๋ฌผ ์ˆ˜์šฉ์•ก์—์„œ ์‹คํ—˜์ด ์ˆ˜ํ–‰๋˜์—ˆ๊ธฐ ๋•Œ๋ฌธ์ด๋ฉฐ, ์ด๋Ÿฌํ•œ ํ™˜๊ฒฝ์—์„œ๋„ [OH-] ์ด์˜จ์œผ๋กœ ๋ถ€์‹์ „๋ฅ˜์˜ ๊ธฐ์šธ๊ธฐ๊ฐ€ ๊ฐ์†Œํ•˜๊ณ  ์žˆ์Œ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. ์ฆ‰ ๋†’์€ ์—ผํ™”๋ฌผ ๋†๋„์—์„œ๋„ ๋†’์€ [OH-] ์กฐ๊ฑด์€ ๋ถ€์‹๊ฑฐ๋™์„ ๊ฐœ์„ ์‹œํ‚ฌ ์ˆ˜ ์žˆ๋‹ค.

Fig. 14 Regression analysis with normalized results
../../Resources/ksm/jksmi.2024.28.4.21/fig14.png

5. ๊ฒฐ ๋ก 

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” 3์ˆ˜์ค€์˜ ์—ผํ™”๋ฌผ ๋†๋„ ๋ฐ 3์ˆ˜์ค€์˜ [Cl-]/[OH-]๋น„๋ฅผ ๊ณ ๋ คํ•˜์—ฌ ๋ถ€์‹์ „๋ฅ˜์˜ ๋ณ€ํ™”๋ฅผ ๋ถ„์„ํ•˜์˜€์œผ๋ฉฐ, ํ…๋˜์˜ ๋ถ€์‹ ์ค‘๋Ÿ‰์„ ํ‰๊ฐ€ํ•˜์˜€๋‹ค. ๋ณธ ์—ฐ๊ตฌ๋ฅผ ํ†ตํ•ด ๋„์ถœ๋œ ๊ฒฐ๋ก ์€ ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค.

1) ์—ผํ™”๋ฌผ ๋†๋„์— ๋”ฐ๋ฅธ ๋ถ€์‹์ „๋ฅ˜ ๋ณ€ํ™” ๊ฑฐ๋™์„ ๋ถ„์„ํ•œ ๊ฒฐ๊ณผ, 0.0mol/l, 0.125mol/l, 0.25mol/l ๊ฐ๊ฐ์˜ ๋ถ€์‹์ „๋ฅ˜ ํ‰๊ท ๊ฐ’์€ 5.13ฮผA/cm2, 17.53ฮผA/cm2, 20.07ฮผA/cm2๋กœ ์ธก์ •๋˜์—ˆ๋‹ค. ๋ถ€์‹์ „๋ฅ˜๋Š” ์—ผํ™”๋ฌผ๋Ÿ‰์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ผ ์ฆ๊ฐ€ํ•˜์˜€์œผ๋ฉฐ, 0.125mol/l ์ด์ƒ์—์„œ๋Š” ํฐ ์ฐจ์ด๊ฐ€ ์—†์—ˆ๋Š”๋ฐ, ์ด์ƒ์˜ ์กฐ๊ฑด์—์„œ๋Š” ๋ถ€์‹ํ™œ์„ฑ๋„๊ฐ€ ์ถฉ๋ถ„ํ•˜๊ธฐ ๋•Œ๋ฌธ์ด๋‹ค.

2) 0.125mol/l๋ฅผ ๊ธฐ์ค€์œผ๋กœ [Cl-]/[OH-]๋น„๋ฅผ ๋ณ€ํ™”์‹œ์ผœ ์ธก์ •๋œ ๋ถ€์‹์ „๋ฅ˜๋ฅผ ๋ถ„์„ํ•œ ๊ฒฐ๊ณผ, ๋ชจ๋“  ์ˆ˜์ค€์—์„œ [OH-]๋น„์˜ ๋†๋„๊ฐ€ ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ๋ถ€์‹์ „๋ฅ˜ ๊ฐ’์ด ๊ฐ์†Œํ•˜์˜€๋‹ค. ๋ชฐ๋น„ 0.3์ผ ๊ฒฝ์šฐ, ๋ถ€์‹์ „๋ฅ˜์˜ ํ‰๊ท ๊ฐ’์€ 15.16 ฮผA/cm2์œผ๋กœ ํ‰๊ฐ€๋˜์—ˆ์œผ๋ฉฐ, 0.6, 0.9๋กœ ์ฆ๊ฐ€ํ• ์ˆ˜๋ก, ๋ถ€์‹์ „๋ฅ˜๋Š” 17.31 ฮผA/cm2, 18.33 ฮผA/cm2์œผ๋กœ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ๊ธฐ์กด์˜ ์—ฐ๊ตฌ์™€ ๋งˆ์ฐฌ๊ฐ€์ง€๋กœ [Cl-]/[OH-]์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ผ ์„ ํ˜•์ ์ธ ๋ถ€์‹์ „๋ฅ˜์˜ ์ฆ๊ฐ€๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ๋†’์€ [OH-]์˜ ๋†๋„๋Š” ๋†’์€ ๋ถ€์‹ํ™˜๊ฒฝ(0.125mol/l)์˜ ์กฐ๊ฑด์—์„œ๋„ ํšจ๊ณผ์ ์ž„์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค.

3) ์ƒ์„ฑ๋œ ๋ถ€์‹๋Ÿ‰์€ ์‹œ๊ฐ„์— ๋”ฐ๋ผ ์„ ํ˜•์ ์œผ๋กœ ์ฆ๊ฐ€ํ•˜์˜€์œผ๋ฉฐ, ์—ผํ™”๋ฌผ๋†๋„๊ฐ€ ๋†’์„์ˆ˜๋ก, [OH-] ๋น„์œจ์ด ๋‚ฎ์„์ˆ˜๋ก ๋ถ€์‹๋Ÿ‰์ด ํฌ๊ฒŒ ํ‰๊ฐ€๋˜์—ˆ๋‹ค. 0.125mol/l ์ธ ์กฐ๊ฑด์—์„œ๋„ ๋†’์€ [OH-]๋ฅผ ๊ฐ€์ง„ ๊ฒฝ์šฐ ๋‚ฎ์€ ๋ถ€์‹๋Ÿ‰์ด ํ‰๊ฐ€๋˜์—ˆ๋‹ค. ๋˜ํ•œ ์ •๊ทœํ™”๋œ ๊ฒฐ๊ณผ๋ฅผ ์ด์šฉํ•˜์—ฌ ๋ถ€์‹์ „๋ฅ˜์™€ ์˜ํ–ฅ์ธ์ž ๊ฐ„์˜ ์ƒ๊ด€์„ฑ์„ ๋ถ„์„ํ•˜์˜€๋‹ค.

4) ๋ณธ ์‹คํ—˜์—์„œ๋Š” ํ…๋˜์˜ ์†Œ์„ ๋ผ๋ฆฌ์˜ ์ ‘์ด‰๋ฉด, ๊ตญ์†Œ๋ถ€์‹, ๋ชจ๋ž˜ ํฌํ™”๋„์˜ ๋ถˆ๊ท ์งˆ์„ฑ์œผ๋กœ ์ธก์ •๋œ ์ „๋ฅ˜์˜ ๋ณ€๋™์„ฑ์ด ํฌ๊ฒŒ ๋ฐœ์ƒํ•˜์˜€๋‹ค. ํ–ฅํ›„ ์—ฐ๊ตฌ์—์„œ๋Š” ๋‚ฎ์€ ์ˆ˜์ค€์˜ ์—ผํ™”๋ฌผ ๋†๋„์™€ ๋…๋ฆฝ ์ ˆ์—ฐ๋œ ์†Œ์„ ์„ ์ด์šฉํ•œ ์ด‰์ง„์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•˜์—ฌ ๋ณ€๋™์„ฑ์ด ๊ฐœ์„ ๋œ ๋ถ€์‹ ์‹คํ—˜์„ ์ˆ˜ํ–‰ํ•  ์˜ˆ์ •์ด๋‹ค.

๊ฐ์‚ฌ์˜ ๊ธ€

๋ณธ ์—ฐ๊ตฌ๋Š” ์ •๋ถ€์˜ ์ง€์›์œผ๋กœ ํ•œ๊ตญ์—ฐ๊ตฌ์žฌ๋‹จ ์ค‘๊ฒฌ์—ฐ๊ตฌ์ž์ง€์›์‚ฌ์—…์˜ ์ง€์›์„ ๋ฐ›์•„ ์ˆ˜ํ–‰๋˜์—ˆ์œผ๋ฉฐ ์ด์— ๊ฐ์‚ฌ๋“œ๋ฆฝ๋‹ˆ๋‹ค(NRF- 2020R1A2C2009462).

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