Mobile QR Code QR CODE
Export citation EndNote




๋‚ด์ง„, ๋ณด์ˆ˜, ๋ณด๊ฐ•, ํด๋ฆฌ์šฐ๋ ˆ์•„, ์žฌ๋ฃŒ ์„ฑ๋Šฅ ํ‰๊ฐ€
seismic, strengthen, reinforcement, PolyUrea, material performance evaluation

  • 1. ์„œ ๋ก 

  • 2. PU์˜ ๊ธฐ๋ณธ ๊ตฌ์„ฑ์š”์†Œ

  • 3. ์‚ฌ์šฉ์žฌ๋ฃŒ ๋ฐ ์‹คํ—˜ ๋ฐฉ๋ฒ•

  •   3.1 ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„

  •   3.2 ์ธ์žฅ๊ฐ•๋„ ๋ฐ ์‹ ์žฅ๋ฅ  ํ‰๊ฐ€ ์‹œํ—˜

  •   3.3 ๋ถ€์ฐฉ์„ฑ๋Šฅ ํ‰๊ฐ€ ์‹œํ—˜

  •   3.4 Shore ๊ฒฝ๋„ ํ‰๊ฐ€ ์‹œํ—˜

  • 4. ์‹คํ—˜ ๊ฒฐ๊ณผ

  •   4.1 ์ธ์žฅ๊ฐ•๋„ ๋ฐ ์‹ ์žฅ๋ฅ  ํ‰๊ฐ€

  •   4.2 ๋ถ€์ฐฉ ์„ฑ๋Šฅ ํ‰๊ฐ€

  •   4.3 Shore ๊ฒฝ๋„ ํ‰๊ฐ€

  •   4.4 FTPU์™€ ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„์˜ ์žฌ๋ฃŒ ํŠน์„ฑ

  • 5. ๊ฒฐ ๋ก 

1. ์„œ    ๋ก 

2015๋…„, ๋ฆฌํžˆํ„ฐ ๊ทœ๋ชจ 6.0 ์ด์ƒ์˜ ๊ฐ•์ง„์ด ๋Œ€๋งŒ ํ•ด์—ญ์— 3๊ฑด, ๋„คํŒ” ๋‚ด๋ฅ™์— 5๊ฑด, ์ผ๋ณธ ํ•ด์—ญ์— 10๊ฑด๊ณผ ๊ฐ™์ด ์ง€์ง„์ด ๋นˆ๋ฒˆํ•˜๊ฒŒ ๋ฐœ์ƒํ•˜์˜€์œผ๋ฉฐ, ํŠนํžˆ ๋„คํŒ”์—์„œ ๋ฐœ์ƒํ•œ ๋ฆฌํžˆํ„ฐ ๊ทœ๋ชจ 7.8์˜ ๊ฐ•์ง„์œผ๋กœ ์ธํ•˜์—ฌ 7์ฒœ๋ช… ์ด์ƒ์˜ ์‚ฌ๋ง์ž๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๋‹ค. ์„ธ ๋‚˜๋ผ์™€ ๊ทผ์ ‘ํ•œ ์šฐ๋ฆฌ๋‚˜๋ผ ์—ญ์‹œ ์ง€์ง„์˜ ๋ฐœ์ƒ ๋นˆ๋„๊ฐ€ ์ฆ๊ฐ€ํ•˜๊ณ  ์žˆ์œผ๋ฉฐ, ์ตœ๊ทผ ๋ฆฌํžˆํ„ฐ ๊ทœ๋ชจ 5.1์˜ ์ง€์ง„์ด ์ถฉ๋‚จ ํƒœ์•ˆ๊ตฐ ํ•ด์—ญ์—์„œ ๋ฐœ์ƒํ•œ ์‚ฌ๋ก€๊ฐ€ ์žˆ๋‹ค.1) ์ด๋Ÿฌํ•œ ์ง€์ง„์˜ ๋ฐœ์ƒ์€ ์ธ๊ฐ„์„ ์œ„ํ˜‘ํ•˜๊ณ  ์‚ถ์˜ ํ„ฐ์ „์„ ๋นผ์•—์•„๊ฐ€๊ณ  ์žˆ๋‹ค.

1988๋…„ 7์›” 1์ผ๋ถ€๋กœ ์šฐ๋ฆฌ๋‚˜๋ผ์—์„  โ€œ๊ฑด์ถ•๋ฌผ์˜ ๋‚ด์ง„๊ตฌ์กฐ ๋ฐ ๋ฐฉ์žฌ์— ๊ด€ํ•œ ์—ฐ๊ตฌโ€๋ฅผ ๊ธฐ์ดˆ๋กœ ๋‚ด์ง„ ์„ค๊ณ„๋ฅผ ์œ„ํ•œ ์‹œํ–‰๋ น์„ ์ œ์ •ํ•˜์˜€์ง€๋งŒ, 1988๋…„ 7์›” ์ด์ „์— ์ง€์€ ์‚ฌํšŒ๊ธฐ๋ฐ˜๊ตฌ์กฐ๋ฌผ๋“ค์€ ์‚ฌ์‹ค์ƒ ์ง€์ง„ํ”ผํ•ด์— ๋ฌด๋ฐฉ๋น„ ์ƒํƒœ๋กœ ๋…ธ์ถœ๋˜์–ด ์žˆ๋‹ค. ์ดํ›„ ์ง€์ง„ํ•˜์ค‘์„ ๊ณ ๋ คํ•˜์—ฌ ๋‹ค์–‘ํ•œ ๊ตฌ์กฐ๋ฌผ์— ๋Œ€ํ•œ ๋ณด์ˆ˜ยท๋ณด๊ฐ• ๋ฐฉ๋ฒ•์— ๋Œ€ํ•œ ๊ฐœ๋ฐœ ๋ฐ ์—ฐ๊ตฌ๊ฐ€ ์ง„ํ–‰๋˜์–ด์ ธ ์™”๋‹ค.2-6) ๊ตญ๋‚ด์˜ ๊ฒฝ์šฐ ์ฒ ๊ทผ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ฌผ์˜ ๋‚ด์ง„์— ๊ด€ํ•œ ๋ณด์ˆ˜ยท๋ณด๊ฐ•๊ณต๋ฒ•์œผ๋กœ๋Š” ๊ฐ•ํŒ ์ ‘์ฐฉ๊ณต๋ฒ•, ์„ฌ์œ ๋ณด๊ฐ•(Fiber-Reinforced Polymer, FRP) ํ‘œ๋ฉด ๋ถ€์ฐฉ ๊ณต๋ฒ•, ๋‹จ๋ฉด์ฆ๊ฐ€ ๊ณต๋ฒ• ๋“ฑ์ด ์‚ฌ์šฉ๋˜๊ณ  ์žˆ๋‹ค. ๊ตญ์™ธ์˜ ๊ฒฝ์šฐ ๊ฐ€๊ณต์ด ์šฉ์ดํ•œ ๊ฐ•ํŒ์„ ์‚ฌ์šฉํ•˜์—ฌ ๊ฐ•ํŒ ์ ‘์ฐฉ ๊ณต๋ฒ•์„ ๋ณด์ˆ˜ยท๋ณด๊ฐ•์˜ ๋ชฉ์ ์œผ๋กœ ์‚ฌ์šฉํ•˜์˜€๋‹ค.7) ํ•˜์ง€๋งŒ ๊ฐ•ํŒ ์ž์ฒด์˜ ๋ฌด๊ฒŒ์™€ ๋„“์€ ๋ณด๊ฐ• ๋ฉด์  ๋ฐ ์ œํ•œ๋œ ์‹œ๊ณต ๊ณต๊ฐ„์ด๋ผ๋Š” ๋ฌธ์ œ์ ๋“ค๋กœ ์ธํ•˜์—ฌ 1990๋…„๋Œ€์— ๊ฐœ๋ฐœ๋œ FRP ํ‘œ๋ฉด ๋ถ€์ฐฉ ๊ณต๋ฒ•์œผ๋กœ ๋Œ€์ฒด ๋˜์—ˆ๋‹ค. ์ด๋Š” ํ† ๋ชฉ ๊ตฌ์กฐ๋ฌผ์˜ ๊ฐ•๋„์ฆ์ง„๊ณผ ๋‚ด๊ตฌ์„ฑ ํ–ฅ์ƒ์— ์žˆ์–ด์„œ ๋‹ค๋ฅธ ์žฌ๋ฃŒ ๋ฐ ๊ณต๋ฒ•๋“ค์— ๋น„ํ•˜์—ฌ ๊ตญโ€ง๋‚ด์™ธ์ ์œผ๋กœ ๋„๋ฆฌ ์ ์šฉ๋˜์–ด ์™”์œผ๋ฉฐ, ๊ตฌ์กฐ๋ฌผ์— ์ƒ๋‹นํ•œ ํšจ๊ณผ๋ฅผ ๋‚˜ํƒ€๋‚ด๋Š” ๊ฒƒ์œผ๋กœ ์ˆ˜๋งŽ์€ ์—ฐ๊ตฌ๊ฒฐ๊ณผ๊ฐ€ ๋ณด๊ณ ๋œ ๋ฐ” ์žˆ๋‹ค.8-14)

FRP ํ‘œ๋ฉด ๋ถ€์ฐฉ ๊ณต๋ฒ•์€ ์ฝ˜ํฌ๋ฆฌํŠธ ๋ถ€์žฌ์— ์—ํญ์‹œ๋ฅผ ๋„ํฌํ•˜์—ฌ FRP ์‹œํŠธ๋ฅผ ๊ฐ์‹ธ๋Š” ๊ณต๋ฒ•์ด๋ฏ€๋กœ ์‹œ๊ณต์ด ๋‹จ์ˆœํ•˜๊ณ  ์„ฑ๋Šฅ์ด ์šฐ์ˆ˜ํ•˜๋‚˜ ๊ท ์ผํ•œ ํ’ˆ์งˆ ํ™•๋ณด๊ฐ€ ์–ด๋ ค์šฐ๋ฉฐ ์žฌ๋ฃŒ๋ฅผ ํ™•๋ณดํ•˜๋Š”๋ฐ ์žˆ์–ด ํ•ด์™ธ์— ์˜์กดํ•˜๊ธฐ ๋•Œ๋ฌธ์— ๊ฐ€๊ฒฉ์ด ๋น„์‹ธ๋‹ค๋Š” ๋‹จ์ ์ด ์žˆ๋‹ค. ๋˜ํ•œ FRP ํ‘œ๋ฉด ๋ถ€์ฐฉ ๊ณต๋ฒ•์— ์‚ฌ์šฉ๋˜๋Š” ์ ‘์ฐฉ์ œ๋Š” ๋ถˆํ•„์š”ํ•œ Interface๋ฅผ ํ˜•์„ฑํ•˜๊ฒŒ ๋˜๋ฉฐ ์ด๋Š” ์‹œ๊ฐ„์ด ๊ฒฝ๊ณผํ•จ์— ๋”ฐ๋ผ ์—ดํ™”, ํƒˆ๋ฝ๊ณผ ๊ฐ™์€ ๋ฌธ์ œ๋ฅผ ์ดˆ๋ž˜ํ•˜๊ณ  ๊ฒฐ๊ตญ ๋ณด์ˆ˜ยท๋ณด๊ฐ• ์„ฑ๋Šฅ์„ ์ €ํ•˜์‹œํ‚จ๋‹ค. FRP ํ‘œ๋ฉด ๋ถ€์ฐฉ ๊ณต๋ฒ•์ด๋‚˜ ๊ฐ•ํŒ ์ ‘์ฐฉ ๊ณต๋ฒ• ๋ฐ ๋‹จ๋ฉด ์ฆ๊ฐ€ ๊ณต๋ฒ•์€ ๋‚ด์ง„ ๋ณด๊ฐ•ํšจ๊ณผ์— ์žˆ์–ด์„œ๋„ ์˜๋ฌธ์„ฑ์ด ์ œ์‹œ ๋˜๊ณ  ์žˆ์œผ๋ฉฐ, ๊ฐ•์ง„์ด ๋ฐœ์ƒํ•˜์˜€์„ ๊ฒฝ์šฐ ์ง€์ง„ํ•˜์ค‘์— ๋Œ€ํ•œ ์ง„๋™๊ณผ ๋ฐ˜๋ณตํ•˜์ค‘์— ์˜ํ•œ ํ”ผํ•ด ์‚ฌ๋ก€๊ฐ€ ๋ณด๊ณ ๋˜๊ณ  ์žˆ์œผ๋ฏ€๋กœ ์ด๋ฅผ ๋Œ€์ฒดํ• ๋งŒํ•œ ๊ธฐ์ˆ  ๊ฐœ๋ฐœ์ด ํ•„์š”ํ•˜๋‹ค.15-16)

ํ˜„์žฌ ํด๋ฆฌ๋จธ๊ณ„ ๊ณ ์—ฐ์„ฑ ์žฌ๋ฃŒ๋ฅผ ํ™œ์šฉํ•œ ๊ธฐ๋ฒ•์ด ๋Œ€์•ˆ์œผ๋กœ ์ œ์‹œ๋˜๊ณ  ์žˆ์œผ๋ฉฐ ๊ณ ๋ถ„์ž ํ™”ํ•ฉ๋ฌผ์ธ ํด๋ฆฌ์šฐ๋ ˆ์•„(PolyUrea, PU)๋Š” ๋น„๊ตฌ์กฐ์šฉ ๋ณด์ˆ˜์žฌ๋ฃŒ๋กœ์จ ๋‹ค์–‘ํ•œ ๋ถ„์•ผ์— ์ ์šฉ์ด ๊ฐ€๋Šฅํ•˜๋‹ค. PU๋Š” ๊ด‘๋ฒ”์œ„ํ•œ ๋ฌผ์„ฑ์˜ ์กฐ์ ˆ์ด ๊ฐ€๋Šฅํ•˜๋ฉฐ ๋›ฐ์–ด๋‚œ ๊ณ„๋ฉด์ ‘์ฐฉ์„ฑ๊ณผ ๊ธฐ๊ณ„์  ๋ฌผ์„ฑ ๋“ฑ์œผ๋กœ ์ธํ•ด ์ ‘์ฐฉ์ œ, ์ฝ”ํŒ…์ œ ๋“ฑ ๋ณตํ•ฉ์žฌ๋ฃŒ๋กœ ๋„๋ฆฌ ์‚ฌ์šฉ๋˜๊ณ  ์žˆ๋‹ค. PU๋Š” ๊ธฐ์กด์— FRP์™€ ๋‹ฌ๋ฆฌ ๊ตฌ์กฐ๋ฌผ๊ณผ ๋ณด์ˆ˜์žฌ๋ฃŒ ์‚ฌ์ด์—์„œ ํƒˆ๋ฝ์ด ๋ฐœ์ƒํ•˜์ง€ ์•Š์•„ ๊ตฌ์กฐ๋ฌผ๊ณผ ๋ณด์ˆ˜์žฌ๋ฃŒ๊ฐ€ ์ผ์ฒด๊ฑฐ๋™์„ ์œ ๋„ํ•  ์ˆ˜ ์žˆ๋‹ค. ๋˜ํ•œ, ์Šคํ”„๋ ˆ์ดํ˜•์‹ ๊ธ‰์†์‹œ๊ณต์ด ๊ฐ€๋Šฅํ•˜๊ณ  ๊ตฌ์กฐ๋ฌผ์— ์ง์ ‘ ๋ถ„์‚ฌํ•˜์—ฌ ๋ณด๊ฐ•ํ•˜๋Š” ๋ฐฉ๋ฒ•์œผ๋กœ ๊ท ์ผํ•œ ํ’ˆ์งˆ์„ ์œ ์ง€ํ•  ์ˆ˜ ์žˆ๋‹ค๋Š” ์žฅ์ ์ด ์žˆ๋‹ค. PU๋ฅผ ์ด์šฉํ•˜์—ฌ ๋ณด๊ฐ• ์„ฑ๋Šฅ์„ ํ–ฅ์ƒ์‹œํ‚จ ์—ฐ์งˆํ˜• ํด๋ฆฌ์šฐ๋ ˆ์•„(Flexible Type PolyUrea, FTPU)๋ฅผ ๊ฐœ๋ฐœํ•˜๊ณ  ์ด๋ฅผ ๊ตฌ์กฐ๋ฌผ์— ์ ์šฉํ•œ ์„ ํ–‰ ์—ฐ๊ตฌ์—์„œ ๋ณด๊ฐ• ์„ฑ๋Šฅ์€ ๋ฏธ๋ฏธํ•œ ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค.17) ์ดํ›„ ๊ธฐ์กด FTPU์˜ ์กฐ์„ฑ๋น„๋ฅผ ๋ณ€ํ™”์‹œ์ผœ ๊ฒฝ์งˆํ˜• ํด๋ฆฌ์šฐ๋ ˆ์•„(Stiff Type PolyUrea, STPU)๋ฅผ ๊ฐœ๋ฐœํ•˜์˜€๋‹ค.18-19) STPU๋Š” FTPU๋ณด๋‹ค ํ–ฅ์ƒ๋œ ์ธ์žฅ๊ฐ•๋„์™€ ๋‚ฎ์€ ์‹ ์žฅ๋ฅ ์˜ ์„ฑ๋Šฅ์„ ๋ฐœํœ˜ํ•œ๋‹ค. ์‹ ์žฅ๋ฅ ์ด ๋†’์œผ๋ฉด ๊ตฌ์กฐ๋ฌผ์˜ ๊ฐ•์„ฑ ํšจ๊ณผ๋ฅผ ์ €ํ•˜์‹œํ‚ค๋Š” ์›์ธ์ด ๋˜๊ธฐ ๋•Œ๋ฌธ์— ์ด๋ฅผ ๋Œ€์ฒดํ•  ์ˆ˜ ์žˆ๋„๋ก ์กฐ์„ฑ๋น„๋ฅผ ๋ณ€ํ™”์‹œ์ผฐ๋‹ค. ๋”ฐ๋ผ์„œ, ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” FTPU์˜ ์กฐ์„ฑ๋น„๋ฅผ ๋ณ€ํ™”์‹œ์ผœ ์ตœ์ ์˜ ๋‚ด์ง„๋ณด๊ฐ•์šฉ ์žฌ๋ฃŒ๋ฅผ ๊ฐœ๋ฐœํ•˜๊ณ  ์žฌ๋ฃŒ ์„ฑ๋Šฅ์„ ๊ฒ€์ฆํ•˜๊ณ ์žํ•œ๋‹ค.

2. PU์˜ ๊ธฐ๋ณธ ๊ตฌ์„ฑ์š”์†Œ

PU์˜ ์ฃผ์ œ(Prepolymer)๋Š” ์ด์†Œ์‹œ์•„๋„ค์ดํŠธ(Iisocyanate)์™€ ๋‹ค์ด์˜ฌ(Diol, Diamine)์˜ ๋ฐ˜์‘์œผ๋กœ ํ˜•์„ฑ๋˜๋ฉฐ, ์ด๋ฅผ ๋””์ด์†Œ์‹œ์•„๋„ค์ดํŠธ(Diisocyanate)๋ผ ํ•œ๋‹ค. Diisocyanate๋Š” ์ง€๋ฐฉ์กฑ(Aliphatic), ๋ฐฉํ–ฅ์กฑ(Aromatic), ์ง€ํ™˜์กฑ(Cycloaliphatic)์œผ๋กœ ๋ถ„๋ฅ˜๋˜๋ฉฐ, 3๊ฐ€์ง€ ๋ชจ๋‘ PU์˜ ์ฃผ์ œ๋กœ ์‚ฌ์šฉ๋  ์ˆ˜ ์žˆ๋‹ค.

Aliphatic Diisocyanate์—๋Š” Hexane Diisocyanate (HDI), Isophorone Diisocyanate (IPDI), Methylene Biscyclohexyl Diisocyanate (H12MDI)๊ฐ€ ์žˆ๋‹ค. Aromatic Diisocyanate๋Š” Toluene Diisocyanate (TDI), Naphthalene Diisocyanate (NDI), Methylene Diphenyl Diisocyanate (MDI), Bitoluene Diisocyanate (TODI)๊ฐ€ ์žˆ์œผ๋ฉฐ, Cycloaliphatic Diisocyanate๋Š” Methylene๊ณผ Cyclo-hexane์— Isocyanate๊ฐ€ ๊ฒฐํ•ฉ๋œ ๊ฒƒ์ด๋‹ค. PU์˜ ํ•ฉ์„ฑ์— ์‚ฌ์šฉ๋˜๋Š” Diisocyanate์˜ ์ผ๋ฐ˜์ ์ธ ๊ตฌ์กฐ์‹์„ Fig. 1์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.20)

Fig. 1

Diisocyanate structural formula

/Resources/kci/JKCI.2017.29.2.131/images/Figure_CONCRETE_29_02_01_F1.jpg

PU์˜ ๊ฒฝํ™”์ œ(Hardener)๋Š” ๋””์•„๋ฏผ(Diamine)์˜ ์‚ฌ์Šฌ ํ™•์žฅ์ž๋Š” ์ผ๋ฐ˜์ ์œผ๋กœ Butanediol (BD), Ethylene Diamine (ED), Methylenebis Chloroaniline (MOCA), Ethylene Gglycol (EG), Hexanediol (HD) ๋“ฑ์ด ์žˆ์œผ๋ฉฐ, PU์˜ ํ•ฉ์„ฑ์— ์‚ฌ์šฉ๋˜๋Š” ์‚ฌ์Šฌ ํ™•์žฅ์ž์˜ ๊ตฌ์กฐ์‹์„ Fig. 2์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.20) PU์˜ ๊ฒฝํ™”์ œ๋กœ ์‚ฌ์šฉ๋˜๋Š” ์‚ฌ์Šฌ ํ™•์žฅ์ž๋Š” ๋ชจ๋…ธ๋จธ(Monomer)๋‚˜ ์˜ฌ๋ฆฌ๊ณ ๋จธ(Oligo-mer)์˜ ํ˜•ํƒœ๋กœ PU์˜ ๋ถ„์ž๋Ÿ‰์„ ์ฆ๊ฐ€์‹œํ‚จ๋‹ค. ์ด๋Š” PU์˜ ๊ฒฐํ•ฉ๋ ฅ์„ ์ฆ๊ฐ€์‹œํ‚ค๋Š” ์—ญํ• ์„ ํ•˜๋ฉฐ PU์˜ ๋ฐ€๋„์™€ ๊ธฐ๊ณ„์  ๋ฌผ์„ฑ์„ ํ–ฅ์ƒ์‹œ์ผœ ์ค€๋‹ค.

Fig. 2

Chain extenders structural formula

/Resources/kci/JKCI.2017.29.2.131/images/Figure_CONCRETE_29_02_01_F2.jpg

๋ณธ ์—ฐ๊ตฌ์— ์‚ฌ์šฉ๋˜๋Š” Diamine ์‚ฌ์Šฌ ํ™•์žฅ์ž๋Š” Isocyanate์™€ ๋น ๋ฅด๊ณ  ๊ฒฉ๋ ฌํ•˜๊ฒŒ ๋ฐ˜์‘ํ•˜์—ฌ Urea group๊ณผ Biuret ๊ฒฐํ•ฉ์„ ํ˜•์„ฑํ•˜๊ฒŒ ๋˜์–ด ์‚ฌ์Šฌ๊ฐ„์˜ ๊ฒฐํ•ฉ์ด ์ด๋ฃจ์–ด์ง„๋‹ค. Biuret ๊ฒฐํ•ฉ์ด๋ž€ Urea group ๋‚ด ์งˆ์†Œ ์›์ž์— ์žˆ๋Š” ๋ฐ˜์‘์„ฑ์ด ํฐ ์ˆ˜์†Œ๊ฐ€ Iocyanate์™€ ๋ฐ˜์‘ํ•˜๋ฉด์„œ ๋งŒ๋“ค์–ด์ง€๋Š” ๋ฌผ์งˆ์„ ๋งํ•œ๋‹ค. ์ด๋Ÿฌํ•œ ๊ณ ๋ถ„์ž ํ˜•์„ฑ์€ ๋น„๊ต์  ์งง์€ ์‹œ๊ฐ„์— ์ง„ํ–‰๋˜๋ฏ€๋กœ ์ „์ฒด ๊ณต์ •์ด ํ•œ ๋‹จ๊ณ„๋กœ ๋‹จ์ถ•๋˜๋Š” ์ด์ ์ด ์žˆ๋‹ค.

3. ์‚ฌ์šฉ์žฌ๋ฃŒ ๋ฐ ์‹คํ—˜ ๋ฐฉ๋ฒ•

3.1 ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„

๊ธฐ์กด ๋ณด๊ฐ•์žฌ๋ฃŒ์˜ ๋ถ€์ฐฉ๊ฑฐ๋™ ์‹คํ—˜์  ์—ฐ๊ตฌ์— ๋”ฐ๋ฅด๋ฉด, FRP ๋ณด๊ฐ• ์‹œํŽธ์€ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ณ„๋ฉด๊ณผ ์—ํญ์‹œ ์‚ฌ์ด์—์„œ ๊ธ‰๊ฒฉํ•œ ๋ถ€์ฐฉํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒ๋˜์—ˆ์„ ๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ํด๋ฆฌ์šฐ๋ ˆ์•„ ๋ณด๊ฐ• ์‹œํŽธ์— ๋น„ํ•ด ๋‚ฎ์€ ๋ถ€์ฐฉ์ „๋‹จํ•˜์ค‘์„ ๋‚˜ํƒ€๋‚œ ๋ฐ” ์žˆ์œผ๋ฉฐ, ์—ํญ์‹œ๋ณด๋‹ค ์—ฐ์„ฑ์ด ์ข‹์•„ ๋ถ€์ฐฉ ์ „๋‹จ์—๋„ˆ์ง€ ํก์ˆ˜์œจ๋„ ์•ฝ 1.2๋ฐฐ ๋†’์€ ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค.21) ๋˜ํ•œ, ํด๋ฆฌ์šฐ๋ ˆ์•„๋กœ ๋ณด๊ฐ•๋œ RC ์Šฌ๋ž˜๋ธŒ์˜ ์„ฑ๋Šฅํ‰๊ฐ€์— ๊ด€ํ•œ ์—ฐ๊ตฌ์—์„œ, ํด๋ฆฌ์šฐ๋ ˆ์•„์˜ ๋ถ€์ฐฉ๊ฐ•๋„๋Š” ์—ํญ์‹œ์˜ ๋ถ€์ฐฉ๊ฐ•๋„๋ณด๋‹ค ์•ฝ ๋‘ ๋ฐฐ ์ด์ƒ ๋†’์€ ์„ฑ๋Šฅ์„ ๋‚˜ํƒ€๋‚œ ๋ฐ” ์žˆ๋‹ค.18) ๋”ฐ๋ผ์„œ ๊ธฐ์กด์˜ FRP ํ‘œ๋ฉด ๋ถ€์ฐฉ ๊ณต๋ฒ•์„ ๋Œ€์ฒด ๋ชฉ์ ์œผ๋กœ ๊ณ ์—ฐ์„ฑ๊ณผ ๊ณ ์ธ์„ฑ ํšจ๊ณผ๋ฅผ ๋‚˜ํƒ€๋‚ด๋Š” ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„๋ฅผ ๊ฐœ๋ฐœํ•˜๊ธฐ ์œ„ํ•ด์„œ Table 1์— ๋‚˜ํƒ€๋‚ธ ๊ตฌ์„ฑ๋ฌผ ๋ฐ ํ•จ์œ ๋Ÿ‰์„ ๊ธฐ๋ณธ ๊ตฌ์„ฑ๋ฌผ๋กœ ์‚ฌ์šฉํ•˜์˜€๋‹ค.17) Table 1์€ ์ผ๋ฐ˜์ ์ธ PU์˜ ์กฐ์„ฑ๋น„๋ฅผ ๋ณ€ํ™”์‹œํ‚จ FTPU์˜ ์ฃผ์ œ์™€ ๊ฒฝํ™”์ œ์˜ ๊ตฌ์„ฑ์š”์†Œ์ด๋‹ค. FTPU์˜ ๊ฒฝ์šฐ, ์„ ํ–‰ ์—ฐ๊ตฌ์—์„œ ๋ณด์ˆ˜โ€ง๋ณด๊ฐ• ์„ฑ๋Šฅ์ด ๋ฏธ๋ฏธํ•œ ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋˜์—ˆ์œผ๋ฉฐ, FTPU๋ณด๋‹ค ๋†’์€ ์ธ์žฅ๊ฐ•๋„์™€ ๋‚ฎ์€ ์‹ ์žฅ๋ฅ ์˜ ์„ฑ๋Šฅ์„ ๊ฐ€์ง€๋Š” STPU๋ฅผ ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„๋กœ ์ ์šฉํ•˜๊ณ ์žํ•œ๋‹ค.

Table 1 Composite of flexible type polyurea

/Resources/kci/JKCI.2017.29.2.131/images/Table_CONCRETE_29_02_01_T1.jpg

์„ ํ–‰์—ฐ๊ตฌ์—์„œ ์ด๋ฏธ ์ธ์žฅ๊ฐ•๋„ 49 MPa๊ณผ ์‹ ์žฅ๋ฅ  150%์˜ STPU๋ฅผ ๊ฐœ๋ฐœํ•˜๊ณ  STPU๋กœ ๋ณด๊ฐ•๋œ RC beam ๊ตฌ์กฐ์‹คํ—˜์—์„œ ๋ฌด๋ณด๊ฐ• ์‹œํŽธ์— ๋น„ํ•˜์—ฌ 10% ํ–ฅ์ƒ๋œ ๊ฒฐ๊ณผ๋ฅผ ๋ณด์—ฌ์ฃผ๊ณ  ์žˆ๋‹ค.18) ์ด์™€ ๋ฐ˜๋Œ€๋กœ Courtney and John์˜ ์—ฐ๊ตฌ์— ๋”ฐ๋ฅด๋ฉด, ํด๋ฆฌ์šฐ๋ ˆ์•„๋กœ ๋ณด๊ฐ•๋œ RC beam ์‹œํŽธ์ด ๋ฌด๋ณด๊ฐ• ์‹œํŽธ๋ณด๋‹ค 1.24๋ฐฐ์˜ ๊ฐ•๋„์ฆ์ง„๊ณผ 2.6๋ฐฐ์˜ ๋ณ€์œ„์—ฐ์„ฑ๋„ ๋Šฅ๋ ฅ์„ ๋ฐœํœ˜ํ•˜์˜€์œผ๋ฉฐ, ์ด๋•Œ ์‚ฌ์šฉํ•œ ํด๋ฆฌ์šฐ๋ ˆ์•„์˜ ์ธ์žฅ๊ฐ•๋„ 14.8 MPa๊ณผ ์‹ ์žฅ๋ฅ  91%์ด๋‹ค.22) ์ธ์žฅ๊ฐ•๋„๊ฐ€ ๋†’์€ ๋ณด์ˆ˜์žฌ๋ฃŒ๋Š” ๊ตฌ์กฐ๋ฌผ์— ์ธ์žฅ์„ฑ๋Šฅ์„ ์ฆ๊ฐ€์‹œํ‚จ๋‹ค๋Š” ์žฅ์ ์ด ์žˆ์ง€๋งŒ ๊ณผ๋„ํ•œ ์ธ์žฅ๊ฐ•๋„์˜ ์„ฑ๋Šฅ์„ ๊ฐ€์ง€๋Š” ์žฌ๋ฃŒ๋ฅผ ์‚ฌ์šฉํ•˜๋Š” ๊ฒƒ์€ ๋น„ํšจ์œจ์ ์ด๋ผ๊ณ  ํŒ๋‹จํ•˜์˜€๋‹ค. ๋”ฐ๋ผ์„œ ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ์ฃผ์ œ์˜ ์กฐ์„ฑ๋น„๋ฅผ ๊ณ ์ •ํ•˜๊ณ  ๊ฒฝํ™”์ œ์˜ ์กฐ์„ฑ๋น„๋งŒ์„ ๋ณ€๊ฒฝํ•˜์—ฌ 150%๊นŒ์ง€ ์‹ ์žฅ๋ฅ ์„ ๋‚ฎ์ถ”๊ณ  ์ธ์žฅ๊ฐ•๋„๋ฅผ ํ–ฅ์ƒ์‹œํ‚ค๋Š” ๋‹จ๊ณ„์  ๋ฐฐํ•ฉ์„ ๋„์ถœํ•˜์˜€๋‹ค.

FTPU์˜ ์ฃผ์ œ ํ•ฉ์„ฑ์˜ ๊ฒฝ์šฐ, Methylene Diphenyl Diisocyanate (MDI) 70%, Polyoxypropylene Glycol 20%, Propylenecarbonate 10%๋ฅผ ์‚ฌ์šฉํ•˜์˜€์œผ๋ฉฐ, ๊ฒฝํ™”์ œ์˜ ๊ฒฝ์šฐ, Polyoxypropylene Diamine 30๏ฝž40%, Polyethertriamine 10๏ฝž20%, Diethyltoluened-imine (DETDA) 5%, Secondary Amine 20๏ฝž30%, Propylene Glycol 2%, Pigment 2%, UV ํก์ˆ˜์ œ 2% ๋ฏธ๋งŒ, ฮณ-glycidoxypropy-ltrimethoxysilane 1%๋ฅผ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ์ด๋ฅผ ๋ฐ”ํƒ•์œผ๋กœ FTPU ์ฃผ์ œ์™€ ๊ฒฝํ™”์ œ์˜ ์กฐ์„ฑ๋น„๋ฅผ ๋ณ€ํ™”์‹œ์ผœ 25 MPa์ด์ƒ์˜ ์ธ์žฅ๊ฐ•๋„์™€ 150%์ดํ•˜์˜ ์‹ ์žฅ๋ฅ ์„ ๋ชฉํ‘œ๋กœ ๋‹จ๊ณ„๋ณ„ 6๊ฐ€์ง€์˜ STPU๋ฅผ ๊ฐœ๋ฐœํ•˜์˜€๋‹ค.

Step 1์€ FTPU์˜ ์กฐ์„ฑ๋น„์™€ ๊ฑฐ์˜ ์œ ์‚ฌํ•˜๊ฒŒ ํ˜ผํ•ฉํ•˜์˜€๋‹ค. FTPU ์ฃผ์ œ ํ•ฉ์„ฑ๊ณผ ๋™์ผํ•œ ์ฃผ์ œ๋ฅผ ์‚ฌ์šฉํ•˜์˜€์œผ๋ฉฐ, ๊ฒฝํ™”์ œ๋Š” Polyoxypropylenediamine 40%, Polyethertriamine 15%, Diethyltoluenedimine 10%, Secondary Amine 30%, Propylene Glycol 2%, Pigment 2%, UV ํก์ˆ˜์ œ 2% ๋ฏธ๋งŒ, ฮณ-glycidoxypro-pyltrimethoxysilane 1%๋ฅผ ์ด์šฉํ•˜์—ฌ 30๏ฝž90ยฐC์—์„œ ๋ฐ˜์‘์‹œ์ผฐ๋‹ค.

Step 2์˜ ์ฃผ์ œ ํ•ฉ์„ฑ์€ FTPU ์ฃผ์ œ ํ•ฉ์„ฑ์—์„œ MDI๋ฅผ 30%๋กœ ๋‚ฎ์ถ”๊ณ  ์ง€๋ฐฉ์กฑ์— ์†ํ•˜๋ฉฐ ๋ฐ˜์‘์†๋„์— ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š” Methy-lene Biscyclohexyl Diisocyanate (H12MDI)๋ฅผ 40%๋ฅผ ์ฒจ๊ฐ€ํ•˜์˜€๋‹ค. Step 2์˜ ๊ฒฝํ™”์ œ ํ•ฉ์„ฑ์€ Step 1์˜ ๊ฒฝํ™”์ œ ํ•ฉ์„ฑ์—์„œ ์‹ ์žฅ๋ฅ ์˜ ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š” Polyoxypropylene Diamine์„ 50%๋กœ ์ฆ๊ฐ€ํ•˜์˜€๊ณ  ์ธ์žฅ๊ฐ•๋„์— ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š” Polyethertriamine์„ 10%๋กœ ๊ฐ์†Œํ•˜์˜€๋‹ค. ๋˜ํ•œ, ๊ฒฝ๋„์™€ ๊ฐ•๋„์— ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š” DETDA๋ฅผ 15%๋กœ ์ฆ๊ฐ€ํ•˜์˜€๊ณ  ๊ฒฝํ™”์‹œ๊ฐ„์„ ๋Šฆ์ถ”๋Š” Secondary Amine์„ 20%๋กœ ๊ฐ์†Œํ•˜์—ฌ ๋ฐ˜์‘์‹œ์ผฐ๋‹ค.

Step 3์˜ ์ฃผ์ œ ํ•ฉ์„ฑ์€ FTPU์˜ ์ฃผ์ œ ํ•ฉ์„ฑ๊ณผ ๊ฐ™์œผ๋ฉฐ ๊ฒฝํ™”์ œ ํ•ฉ์„ฑ์€ Step 2์˜ ๊ฒฝํ™”์ œ ํ•ฉ์„ฑ์—์„œ Polyoxypropylene Diamine์„ 30%๋กœ ์ค„์˜€๊ณ  DETDA์„ 25%๊นŒ์ง€ ์ฆ๊ฐ€ํ•˜์˜€์œผ๋ฉฐ Secon-dary Amine์€ ๋‹ค์‹œ 30%๋กœ ์ฆ๊ฐ€ํ•˜์—ฌ ๋ฐ˜์‘์‹œ์ผฐ๋‹ค.

Step 4๋Š” Step 3์˜ ๊ฒฝํ™”์ œ ํ•ฉ์„ฑ์—์„œ Polyoxypropylene Diamine๋ฅผ ๋‹ค์‹œ 40%๋กœ ์ฆ๊ฐ€์‹œํ‚ค๊ณ , Secondary Amine์„ 20%๋กœ ๋‚ฎ์ถ”์–ด ๋ฐ˜์‘์‹œ์ผฐ๋‹ค.

Step 5์˜ ๊ฒฝํ™”์ œ ํ•ฉ์„ฑ์€ Step 4์˜ ๊ฒฝํ™”์ œ ํ•ฉ์„ฑ์—์„œ Polye-thertriamine๋ณด๋‹ค ๋‚ฎ์€ ๋ถ„์ž๋Ÿ‰์ธ Polyetheramine๋ฅผ 20% ์ฒจ๊ฐ€ํ•˜์˜€์œผ๋ฉฐ, DETDA 20%, Secondary Amine์„ 5%๋กœ ๋‚ฎ์ถ”์–ด ๋ฐ˜์‘์‹œ์ผฐ๋‹ค.

Step 6์˜ ๊ฒฝํ™”์ œ ํ•ฉ์„ฑ์€ Step 5์˜ ๊ฒฝํ™”์ œ ํ•ฉ์„ฑ์—์„œ Polye-theramine์„ 10%๋กœ ๋‚ฎ์ถ”์—ˆ๊ณ  DETDA๋ฅผ 30%๋กœ ์ฆ๊ฐ€์‹œ์ผœ ๋ฐ˜์‘์‹œ์ผฐ๋‹ค. Step 1๋ถ€ํ„ฐ 6๊นŒ์ง€๋Š” ๊ฐ๊ฐ์˜ ์ฃผ์ œ์™€ ๊ฒฝํ™”์ œ๋ฅผ 30๏ฝž90ยฐC(์ตœ์  75ยฐC)์—์„œ ๋ฐ˜์‘์‹œ์ผœ ์ค‘ํ•ฉํ•˜์˜€์œผ๋ฉฐ, Table 2๋Š” ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„๋ฅผ ๊ฐœ๋ฐœํ•˜๋Š” ๋ฐ์— ์žˆ์–ด ์ฃผ์ œ์™€ ๊ฒฝํ™”์ œ์˜ ํ˜ผ์ž…๋ฅ ์„ ๋ณ€ํ™”์‹œํ‚ค๋ฉด์„œ ๋‹จ๊ณ„๋ณ„๋กœ ๊ฐœ๋ฐœํ•œ ๋ฐฐํ•ฉ์˜ ๊ตฌ์„ฑ์š”์†Œ์ด๋‹ค.

Table 2 Composite of stiff type polyurea

/Resources/kci/JKCI.2017.29.2.131/images/Table_CONCRETE_29_02_01_T2.jpg

3.2 ์ธ์žฅ๊ฐ•๋„ ๋ฐ ์‹ ์žฅ๋ฅ  ํ‰๊ฐ€ ์‹œํ—˜

๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„ ๊ฐœ๋ฐœ์— ์žˆ์–ด ๊ณ ์—ฐ์„ฑ ๋ฐ ๊ณ ์ธ์„ฑ ํšจ๊ณผ๋ฅผ ํŒ๋‹จํ•˜๊ธฐ ์œ„ํ•ด์„œ ์ธ์žฅ๊ฐ•๋„ ๋ฐ ์‹ ์žฅ๋ฅ  ํ‰๊ฐ€ ์‹œํ—˜์€ KS M 6518(๊ฐ€ํ™ฉ ๊ณ ๋ฌด ๋ฌผ๋ฆฌ ์‹œํ—˜๋ฐฉ๋ฒ•)์— ์ค€ํ•˜์—ฌ ์ธก์ •ํ•˜์˜€๋‹ค. FTPU์˜ ์กฐ์„ฑ๋น„๋ฅผ ๋‹จ๊ณ„๋ณ„๋กœ ๋ณ€ํ™”์‹œํ‚จ STPU๊ฐ€ ์ ˆ๋‹จ์— ์ด๋ฅด๋Š” ์ตœ๋Œ€์‘๋ ฅ(์ธ์žฅ๊ฐ•๋„) ๋ฐ ์ ˆ๋‹จ ์‹œ์˜ ์‹ ์žฅ๋ฅ ์„ ์ธก์ •ํ•˜๋Š” ๋ฐ ๋ชฉ์ ์ด ์žˆ๋‹ค. ์‹œํ—˜์‹œํŽธ์€ KS M 6518์— ๋‚˜ํƒ€๋‚˜ ์žˆ๋Š” ์•„๋ นํ˜• 3ํ˜ธํ˜• ํฌ๊ธฐ๋กœ ํ‰ํ–‰๋ถ€๋ถ„์˜ ๋„ˆ๋น„ 5 mm, ํ‰ํ–‰๋ถ€๋ถ„์˜ ๊ธธ์ด 20 mm, ํ‰ํ–‰๋ถ€๋ถ„์˜ ๋‘๊ป˜ 3 mm ์ดํ•˜, ๋ˆˆ๊ธˆ ๊ฑฐ๋ฆฌ 20 mm์ด๋ฉฐ, Fig. 3(a)์— ๋‚˜ํƒ€๋ƒˆ๋‹ค. ์•„๋ นํ˜• 3ํ˜ธํ˜• ํฌ๊ธฐ๋กœ ์žฌ๋‹จํ•  ์ˆ˜ ์žˆ๋Š” ํ‹€์นผ์€ Fig. 3(b)์™€ ๊ฐ™์œผ๋ฉฐ, Fig. 3(c)์™€ ๊ฐ™์ด ์ธ์žฅ ์‹œํ—˜๊ธฐ๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ์‹œํ—˜์ฒด๋ฅผ ์–‘์ชฝ ์ง€๊ทธ์— ๊ณ ์ •์‹œ์ผœ(์‹œํ—˜ ์ค‘์— ๋น„ํ‹€๋ฆผ, ์ง‘๊ฒŒ ์ดํƒˆ์ด ๋ฐœ์ƒํ•˜์ง€ ์•Š๋„๋ก ์ •ํ™•ํ•˜๊ฒŒ ์ง‘๊ฒŒ์— ๋ฌผ๋ฆผ) ํ•˜์ค‘์„ ๊ฐ€ํ•˜์—ฌ ์ธ์žฅ๊ฐ•๋„ ๋ฐ ์‹ ์žฅ๋ฅ ์„ ์ธก์ •ํ•˜์˜€๋‹ค. ์ธก์ • ์‹œ ์ธ์žฅ ์†๋„๋Š” 500 mm/min์œผ๋กœ ํ•˜์˜€์œผ๋ฉฐ ์ธ์žฅ๊ฐ•๋„์˜ ์ธก์ •์€ ์‹œํ—˜ํŽธ์ด ๋Š์–ด์งˆ ๋•Œ๊นŒ์ง€ ์ตœ๋Œ€ํ•˜์ค‘์„ ์ฝ๊ณ  ์‹ (1)์„ ์ด์šฉํ•˜์—ฌ ๊ณ„์‚ฐํ•˜์˜€์œผ๋ฉฐ ์‹œํ—˜ํŽธ 3๊ฐœ์˜ ํ‰๊ท ๊ฐ’์œผ๋กœ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. ์‹ ์žฅ๋ฅ ์˜ ์ธก์ •์€ ํŒŒ๋‹จ์‹œ์˜ ๋ˆˆ๊ธˆ์‚ฌ์ด์˜ ๊ธธ์ด๋ฅผ mm๋‹จ์œ„๊นŒ์ง€ ์ธก์ •ํ•˜์˜€์œผ๋ฉฐ ์‹ (2)๋ฅผ ์ด์šฉํ•˜์—ฌ ๊ณ„์‚ฐํ•˜์˜€์œผ๋ฉฐ ์‹œํ—˜ํŽธ 3๊ฐœ์˜ ํ‰๊ท ๊ฐ’์œผ๋กœ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

Fig. 3

Tensile strength and percent elongation test

/Resources/kci/JKCI.2017.29.2.131/images/Figure_CONCRETE_29_02_01_F3.jpg

/Resources/kci/JKCI.2017.29.2.131/images/PIC369D.gif (1)

์—ฌ๊ธฐ์„œ, /Resources/kci/JKCI.2017.29.2.131/images/PIC36FB.gif๋Š” ์ธ์žฅ๊ฐ•๋„(MPa), /Resources/kci/JKCI.2017.29.2.131/images/PIC3789.gif๋Š” ์ตœ๋Œ€ํ•˜์ค‘(N), /Resources/kci/JKCI.2017.29.2.131/images/PIC37A9.gif๋Š” ์‹œํ—˜ํŽธ์˜ ๋‹จ๋ฉด์ (mm2)์„ ๋‚˜ํƒ€๋‚ธ๋‹ค.

/Resources/kci/JKCI.2017.29.2.131/images/PIC3856.gif (2)

์—ฌ๊ธฐ์„œ, /Resources/kci/JKCI.2017.29.2.131/images/PIC3896.gif๋Š” ์‹ ์žฅ๋ฅ (%), /Resources/kci/JKCI.2017.29.2.131/images/PIC38D5.gif๋Š” ๋ˆˆ๊ธˆ๊ฑฐ๋ฆฌ(mm), /Resources/kci/JKCI.2017.29.2.131/images/PIC38F5.gif๋Š” ์ ˆ๋‹จ๋  ๋•Œ์˜ ๋ˆˆ๊ธˆ๊ฑฐ๋ฆฌ(mm)์„ ๋‚˜ํƒ€๋‚ธ๋‹ค.

3.3 ๋ถ€์ฐฉ์„ฑ๋Šฅ ํ‰๊ฐ€ ์‹œํ—˜

๋ณด๊ฐ•์žฌ์˜ ๋ณด๊ฐ•์„ฑ๋Šฅ์„ ํ‰๊ฐ€ํ•˜๋Š” ์ฃผ์š” ํ•ญ๋ชฉ ์ค‘ ํ•˜๋‚˜๋กœ์จ ๋ถ€์ฐฉ์„ฑ๋Šฅ ํ‰๊ฐ€ ์‹œํ—˜๋ฐฉ๋ฒ•์ด ์žˆ๋‹ค. ํ˜„์žฌ ๊ตฌ์กฐ๋ฌผ์˜ ๋ณด์ˆ˜โ€ง๋ณด๊ฐ•๊ณต๋ฒ•์œผ๋กœ ๊ฐ€์žฅ ์ผ๋ฐ˜ํ™”๋˜์–ด ์žˆ๋Š” FRP ํ‘œ๋ฉด ๋ถ€์ฐฉ ๊ณต๋ฒ•์˜ ๊ฒฝ์šฐ ๊ฐ€์žฅ ํฐ ๋ฌธ์ œ์ ์ค‘ ํ•˜๋‚˜๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ๋ชจ์žฌ์™€์˜ ๋ถ€์ฐฉ์„ฑ๋Šฅ์— ๋”ฐ๋ผ ๋ณด๊ฐ•๊ณต๋ฒ•์˜ ์„ฑ๋Šฅ์ด ํฌ๊ฒŒ ์ขŒ์šฐ๋˜๋ฉฐ, ์‹œ๊ฐ„์˜ ๊ฒฝ๊ณผ์— ๋”ฐ๋ผ ์—ดํ™”, ํƒˆ๋ฝ๊ณผ ๊ฐ™์€ ๋ฌธ์ œ๊ฐ€ ๋ฐœ์ƒํ•˜์—ฌ ๋ณด์ˆ˜โ€ง๋ณด๊ฐ• ์„ฑ๋Šฅ์„ ์ €ํ•˜์‹œํ‚จ๋‹ค. ๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ๋ถ€์ฐฉ์„ฑ๋Šฅ ํ‰๊ฐ€ ์‹œํ—˜์€ KS F 4922(ํด๋ฆฌ์šฐ๋ ˆ์•„ ์ˆ˜์ง€ ๋„๋ง‰ ๋ฐฉ์ˆ˜์žฌ)์— ์ค€ํ•˜์—ฌ ์ธก์ •ํ•˜์˜€๋‹ค. ์‹œํ—˜์šฉ ๋ฐ‘ํŒ์€ KS F 4922์— ๋‚˜ํƒ€๋‚˜ ์žˆ๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ ํ‰ํŒ์œผ๋กœ ํฌ๊ธฐ๋Š” 300 mm ร— 300 mm ร— 60 mm์ด๋‹ค. ์ฝ˜ํฌ๋ฆฌํŠธ ํ‰ํŒ ์œ„์— FTPU์˜ ์กฐ์„ฑ๋น„๋ฅผ ๋ณ€ํ™”์‹œํ‚จ ๊ฐ๊ฐ์˜ STPU๋ฅผ ๋„ํฌํ•˜์—ฌ ์ผ์ • ์‹œ๊ฐ„๋™์•ˆ ๊ฑด์กฐ์‹œ์ผฐ๋‹ค. ๊ทธ๋ฆฌ๊ณ  STPU๊ฐ€ ๋„ํฌ๋œ ์‹œํ—˜์ฒด์— Fig. 4(a)์™€ ๊ฐ™์ด ์ธ์žฅ์šฉ ์ง€๊ทธ(Dolly)๋ฅผ 2์•กํ˜• ์—‘ํญ์‹œ ์ ‘์ฐฉ์ œ๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ๋ถ€์ฐฉํ•œ๋‹ค. ๋ถ€์ฐฉ๋ฉด์ ์€ 40 mm ร— 40 mm์ด๋ฉฐ ์ธ์žฅ์šฉ ์ง€๊ทธ๊ฐ€ ๋ถ€์ฐฉ๋œ ์ธก๋ฉด ๋ถ€๋ถ„์„ ๊ทธ๋ผ์ธ๋” ์ปคํ„ฐ๋กœ ์ฝ˜ํฌ๋ฆฌํŠธ ํ‰ํŒ์— ๋„๋‹ฌํ•  ๋•Œ๊นŒ์ง€ ์ ˆ๋‹จํ•˜์˜€๋‹ค.

Fig. 4

Pull off test

/Resources/kci/JKCI.2017.29.2.131/images/Figure_CONCRETE_29_02_01_F4.jpg

์ธ์žฅ์šฉ ์ง€๊ทธ๋Š” ๋„ˆํŠธ ํ˜•์‹์œผ๋กœ ๋˜์–ด์žˆ์–ด Fig. 4(b)์™€ ๊ฐ™์ด ์‹œํ—˜๊ธฐ์™€ ์—ฐ๊ฒฐํ•  ์ˆ˜ ์žˆ๋‹ค. Fig. 4(b)๋Š” ๋ถ€์ฐฉ์„ฑ๋Šฅ ์‹คํ—˜ ์ „๊ฒฝ์„ ๋ณด์—ฌ์ฃผ๊ณ  ์žˆ์œผ๋ฉฐ ๊ฐ๊ฐ์˜ ์‹œํ—˜์ฒด์— ์ธ์žฅ์šฉ ์ง€๊ทธ๋ฅผ 3๊ฐœ์”ฉ ๋ถ€์ฐฉํ•˜์—ฌ ์ตœ๋Œ€ ๊ฐ•๋„๋ฅผ ์ธก์ •ํ•˜์˜€๋‹ค. ์ธก์ • ์‹œ ์ธ์žฅ ์†๋„๋Š” 2 mm/min๋กœ ํ•˜์˜€์œผ๋ฉฐ ์ธก์ •๋œ ์ตœ๋Œ€ ๊ฐ•๋„๋Š” 3๊ฐœ์˜ ํ‰๊ท ๊ฐ’์„ ์‚ฌ์šฉํ•˜์˜€๊ณ  ๊ณ„์‚ฐ์€ ์‹ (3)์„ ์ด์šฉํ•˜์—ฌ ๊ณ„์‚ฐํ•˜์˜€๋‹ค.

/Resources/kci/JKCI.2017.29.2.131/images/PIC3954.gif (3)

์—ฌ๊ธฐ์„œ, /Resources/kci/JKCI.2017.29.2.131/images/PIC39D2.gif๋Š” ๋ถ€์ฐฉ๊ฐ•๋„(N/mm2), /Resources/kci/JKCI.2017.29.2.131/images/PIC3A02.gif๋Š” ์ตœ๋Œ€ํ•˜์ค‘(N), /Resources/kci/JKCI.2017.29.2.131/images/PIC3A51.gif๋Š” ์‹œํ—˜์ฒด์˜ ๋‹จ๋ฉด์ (mm2)์„ ๋‚˜ํƒ€๋‚ธ๋‹ค.

3.4 Shore ๊ฒฝ๋„ ํ‰๊ฐ€ ์‹œํ—˜

๊ฒฝ๋„์ธก์ •์€ ์žฌ๋ฃŒ์˜ ๊ธฐ๊ณ„์  ์„ฑ์งˆ์„ ์•Œ์•„๋‚ด๋Š” ๊ฐ€์žฅ ๊ฐ„๋‹จํ•œ ๋ฐฉ๋ฒ• ์ค‘์— ํ•˜๋‚˜์ด๋‹ค. ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„์˜ ์ฃผ์ œ์™€ ๊ฒฝํ™”์ œ ๋ฐ˜์‘ ์ƒํƒœ๋‚˜ ์—ด์ฒ˜๋ฆฌ ์ƒํƒœ ๋“ฑ์„ ํŒ๋‹จํ•˜๊ธฐ ์œ„ํ•˜์—ฌ ๊ฒฝ๋„ ํ‰๊ฐ€ ์‹œํ—˜์€ KS M ISO 7619-1(๊ฐ€ํ™ฉ ๊ณ ๋ฌด ๋ฐ ์—ด๊ฐ€์†Œ์„ฑ ๊ณ ๋ฌด-์••์ž… ๊ฒฝ๋„ ์ธก์ • ๋ฐฉ๋ฒ•)์„ ์ค€ํ•˜์—ฌ ์ธก์ •ํ•˜์˜€๋‹ค. KS M ISO 7619-1์— ์ œ์‹œ๋œ ๋“€๋กœ๋ฏธํ„ฐ๋ฒ•(Shore ๊ฒฝ๋„)์œผ๋กœ ์ธก์ • ์‹œ ์‚ฌ์šฉ๋˜๋Š” ๊ฒฝ๋„๊ณ„๋Š” Aํ˜•๊ณผ Dํ˜•์ด ์žˆ๋‹ค. Aํ˜•๊ณผ Dํ˜• ๊ฒฝ๋„๊ณ„์˜ ๊ฐ€์žฅ ํฐ ์ฐจ์ด์ ์€ Fig. 5(a)์™€ ๊ฐ™์ด ๊ฒฝ๋„๋ฅผ ์ธก์ •ํ•˜๋Š” ์••์นจ์ด๋‹ค. Dํ˜•์˜ ์••์นจ์€ Aํ˜•์˜ ์••์นจ๋ณด๋‹ค ๋น„๊ต์  ๋พฐ์กฑํ•œ ํ˜•์ƒ์„ ๋‚˜ํƒ€๋‚ด๊ธฐ ๋•Œ๋ฌธ์— Aํ˜• ๊ฒฝ๋„๊ณ„๋ฅผ ๊ฐ€์ง€๊ณ  90 ์ด์ƒ์˜ ๊ฒฝ๋„๋ฅผ ์ธก์ •ํ•˜๋Š” ๊ฒฝ์šฐ์—๋Š” Dํ˜• ๊ฒฝ๋„๊ณ„๋ฅผ ์‚ฌ์šฉํ•œ๋‹ค. Fig. 5(b)๋Š” ์ธก์ •์— ์‚ฌ์šฉ๋œ Dํ˜• ๊ฒฝ๋„๊ณ„์ด๋ฉฐ, Fig. 5(c)์™€ ๊ฐ™์ด ๊ฒฝ๋„๋ฅผ ์ธก์ •ํ•˜์˜€๋‹ค.

Fig. 5

Shore hardness test

/Resources/kci/JKCI.2017.29.2.131/images/Figure_CONCRETE_29_02_01_F5.jpg

4. ์‹คํ—˜ ๊ฒฐ๊ณผ

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” ๊ฐ๊ฐ์˜ ์‹คํ—˜์— ์žˆ์–ด STPU ๊ฒฝํ™”์ œ ์ค‘ ์†Œํฌ์ œ๋กœ ฮณ-glycidoxypropyltrimethoxysilane 1%๋ฅผ ์ฒจ๊ฐ€ํ•œ ๊ฒฝ์šฐ์™€ ์ฒจ๊ฐ€ํ•˜์ง€ ์•Š์€ ๊ฒฝ์šฐ์— ๋Œ€ํ•ด์„œ ์‹คํ—˜์„ ์ง„ํ–‰ํ•˜์˜€์œผ๋ฉฐ ์‹คํ—˜ ๊ฒฐ๊ณผ๋Š” ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค.

4.1 ์ธ์žฅ๊ฐ•๋„ ๋ฐ ์‹ ์žฅ๋ฅ  ํ‰๊ฐ€

๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„์— ๋Œ€ํ•˜์—ฌ ์†Œํฌ์ œ๋ฅผ ์ฒจ๊ฐ€ํ•œ ๊ฒฝ์šฐ์™€ ์ฒจ๊ฐ€ํ•˜์ง€ ์•Š์€ ๊ฒฝ์šฐ์— ๋Œ€ํ•œ ์ง€์†์‹œ๊ฐ„์˜ ๊ฒฐ๊ณผ ๊ทธ๋ž˜ํ”„๋ฅผ Fig. 6์— ๋‚˜ํƒ€๋ƒˆ๋‹ค. ์šฐ์„  Step 1์˜ ์ง€์†์‹œ๊ฐ„์€ ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 10์ดˆ์˜€์œผ๋ฉฐ ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 5์ดˆ ์ดํ•˜๋กœ ๋นจ๋ผ์กŒ๋‹ค. Step 2์˜ ์ง€์†์‹œ๊ฐ„์€ ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 15์ดˆ์˜€๊ณ  ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 10์ดˆ ์ดํ•˜๋กœ ๋นจ๋ผ์กŒ๋‹ค. Step 3๋ถ€ํ„ฐ 6๊นŒ์ง€์˜ ์ง€์†์‹œ๊ฐ„์€ ์†Œํฌ์ œ ์œ ๋ฌด์— ์ƒ๊ด€์—†์ด ๊ฐ๊ฐ 40, 30, 20, 20์ดˆ๋กœ ์ธก์ •๋˜์—ˆ๋‹ค. Step 2์˜ ์ฃผ์ œ ํ•ฉ์„ฑ์—์„œ H12MDI๋ฅผ 40 % ์น˜ํ™˜ํ•˜์˜€๋Š”๋ฐ ์ง€์†์‹œ๊ฐ„์€ ์•ฝ๊ฐ„ ์ฆ๊ฐ€ํ•˜์˜€์œผ๋‚˜ ํฐ ์˜ํ–ฅ์„ ๋ฏธ์น˜์ง€ ์•Š์€ ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค. ์˜คํžˆ๋ ค ๊ฒฝํ™”์ œ ์„ฑ๋ถ„ ์ค‘์—์„œ DETDA์˜ ์ฆ๊ฐ€์™€ Secondary Amine์˜ ๊ฐ์†Œ๊ฐ€ ์ง€์†์‹œ๊ฐ„์— ์˜ํ–ฅ์ด ์žˆ๋‹ค๊ณ  ํŒ๋‹จํ•˜์˜€๋‹ค. ํŠนํžˆ, DETDA์™€ Secondary Amine ๋น„์œจ์ด ๊ฐ€์žฅ ๋งŽ์€ Step 3์—์„œ ์ง€์†์‹œ๊ฐ„์ด ์ œ์ผ ๋†’๊ฒŒ ์ธก์ •๋˜์—ˆ์œผ๋ฉฐ ์ดํ›„ Secondary Amine์„ ๊ฐ์†Œ์‹œํ‚จ Step 5, 6์—์„œ 20์ดˆ๋กœ Step 1, 2๋ณด๋‹ค ๋Šฆ์ถฐ์ง„ ๊ฒƒ์„ ํ™•์ธํ•˜์˜€๋‹ค.

Fig. 6

Hardening time test results

/Resources/kci/JKCI.2017.29.2.131/images/Figure_CONCRETE_29_02_01_F6.jpg

Fig. 7์€ ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„์— ๋Œ€ํ•˜์—ฌ ์†Œํฌ์ œ๋ฅผ ์ฒจ๊ฐ€ํ•œ ๊ฒฝ์šฐ์™€ ์ฒจ๊ฐ€ํ•˜์ง€ ์•Š์€ ๊ฒฝ์šฐ์— ๋Œ€ํ•œ ์ธ์žฅ๊ฐ•๋„๋ฅผ ์ธก์ •ํ•œ ๊ฒฐ๊ณผ ๊ทธ๋ž˜ํ”„์ด๋‹ค. Step 1์˜ ์ธ์žฅ๊ฐ•๋„๋Š” ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 18 MPa ์ด์ƒ์ด๋ฉฐ ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 16 MPa ์ดํ•˜๋กœ ๋–จ์–ด์กŒ์œผ๋ฉฐ, Step 2์˜ ์ธ์žฅ๊ฐ•๋„๋Š” ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 19 MPa ์ด์ƒ์ด๋ฉฐ ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 19 MPa ์ •๋„๋กœ ๊ฐ™์€ ๊ฐ’์ด ์ธก์ •๋˜์—ˆ๋‹ค. Step 3์˜ ์ธ์žฅ๊ฐ•๋„๋Š” ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 21 MPa ์ด์ƒ์ด๋ฉฐ ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 20 MPa ์ดํ•˜๋กœ ๋–จ์–ด์กŒ์œผ๋ฉฐ, Step 4์˜ ์ธ์žฅ๊ฐ•๋„๋Š” ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 22 MPa ์ด์ƒ์ด๋ฉฐ ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 21 MPa ์ดํ•˜๋กœ ๋–จ์–ด์กŒ๋‹ค.

Fig. 7

Tensile strength test results

/Resources/kci/JKCI.2017.29.2.131/images/Figure_CONCRETE_29_02_01_F7.jpg

Polyethertriamine์€ ๋ง์‚ฌ๊ตฌ์กฐ์˜ ํ˜•ํƒœ๋กœ ํ•จ์œ ๋Ÿ‰์— ๋”ฐ๋ผ ํƒ„์„ฑ์ด ์ฆ๊ฐ€ํ•˜๋ฉฐ ๊ฐ•๋„์— ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š” ๊ตฌ์„ฑ์š”์†Œ์ด์ง€๋งŒ Step 2์—์„œ ํ•จ์œ ๋Ÿ‰์„ ์ฆ๊ฐ€ํ•˜์˜€์„ ๋•Œ ์ธ์žฅ๊ฐ•๋„๊ฐ€ ์ฆ๊ฐ€ํ•œ ๋ฐ˜๋ฉด ๊ทธ ์ดํ›„ ๋‹จ๊ณ„๋ณ„ ๋ฐฐํ•ฉ์—์„œ๋Š” ํฐ ์˜ํ–ฅ์„ ๋ฏธ์น˜์ง€ ๋ชปํ•˜๋Š” ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค. ์ธ์žฅ๊ฐ•๋„์˜ ๊ฒฝ์šฐ์—๋„ DETDA๊ฐ€ ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ์ธ์žฅ๊ฐ€๋„๊ฐ€ ํ–ฅ์ƒ๋˜๋Š” ๊ฒƒ์„ ํ™•์ธํ•˜์˜€์œผ๋ฉฐ Step 2๋ถ€ํ„ฐ 4๊นŒ์ง€๋Š” DETDA๊ฐ€ ์ง€๋ฐฐ์ ์ด๋ผ๊ณ  ํŒ๋‹จํ•˜์˜€๋‹ค. Step 5์˜ ์ธ์žฅ๊ฐ•๋„๋Š” ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 24 MPa ์ด์ƒ์ด๋ฉฐ ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 22 MPa ์ดํ•˜๋กœ ๋–จ์–ด์กŒ์œผ๋ฉฐ, Step 6์˜ ์ธ์žฅ๊ฐ•๋„๋Š” ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 26 MPa ์ด์ƒ์ด๋ฉฐ ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 24 MPa ์ดํ•˜๋กœ ๋–จ์–ด์กŒ๋‹ค. Polyethertriamine๋ณด๋‹ค ๋‚ฎ์€ ๋ถ„์ž๋Ÿ‰์ธ Polyetheramine๋ฅผ ์ฒจ๊ฐ€ํ•œ Step 5, 6์—์„œ ์ธ์žฅ๊ฐ€๋„๊ฐ€ ํ›จ์”ฌ ์ฆ๊ฐ€ํ•˜๋Š” ๊ฒƒ์„ ํ™•์ธํ•  ์ˆ˜ ์žˆ์—ˆ๋‹ค. ์†Œํฌ์ œ๋ฅผ ์‚ฌ์šฉํ•˜์˜€์„ ๊ฒฝ์šฐ 1๏ฝž2 MPa ์ •๋„์˜ ์ธ์žฅ๊ฐ•๋„๊ฐ€ ๋†’๊ฒŒ ์ธก์ •๋˜์—ˆ์Œ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค.

Fig. 8์€ ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„์— ๋Œ€ํ•˜์—ฌ ์†Œํฌ์ œ๋ฅผ ์ฒจ๊ฐ€ํ•œ ๊ฒฝ์šฐ์™€ ์ฒจ๊ฐ€ํ•˜์ง€ ์•Š์€ ๊ฒฝ์šฐ์— ๋Œ€ํ•œ ์‹ ์žฅ๋ฅ ์„ ์ธก์ •ํ•œ ๊ฒฐ๊ณผ ๊ทธ๋ž˜ํ”„์ด๋‹ค. Step 1์˜ ์‹ ์žฅ๋ฅ ์€ ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 400% ์ด์ƒ์ด๋ฉฐ ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 350%๋กœ ์ธก์ •๋˜์—ˆ๋‹ค. Step 2์˜ ์‹ ์žฅ๋ฅ ์€ ์†Œํฌ์ œ ์‚ฌ์šฉ ์œ ๋ฌด๋ฅผ ๋– ๋‚˜ 330% ์ •๋„๋ฉฐ, Step 3์˜ ์‹ ์žฅ๋ฅ ์€ ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 280% ์ด์ƒ, ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 330%๋กœ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. Step 4๋ถ€ํ„ฐ 6๊นŒ์ง€ ์‹ ์žฅ๋ฅ ์€ ์†Œํฌ์ œ ์‚ฌ์šฉ ์œ ๋ฌด๋ฅผ ๋– ๋‚˜ ๊ฐ๊ฐ 240, 170, 150%๋กœ ์ธก์ •๋˜์—ˆ๋‹ค. Step 2, 3์—์„œ Polyoxypropylene Diamine์˜ ์ฆ๊ฐ์— ๋Œ€ํ•ด์„œ ์‹ ์žฅ๋ฅ ์—๋Š” ์˜ํ–ฅ์ด ์—†๋Š” ๊ฒƒ์œผ๋กœ ํŒ๋‹จํ•˜์˜€๋‹ค. Polyoxypropylene Diamine์˜ ๊ตฌ์กฐ์ ์œผ๋กœ ์‹ค๊ณผ ๊ฐ™์€ ์„ ํ˜•๊ตฌ์กฐ๋ฅผ ๊ฐ€์ง€๊ธฐ ๋•Œ๋ฌธ์— ์‹ ์œจ์— ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š” ์š”์†Œ ์ค‘ ํ•˜๋‚˜์ด์ง€๋งŒ ๊ทธ๋ณด๋‹ค๋Š” ์กฐ๋ฐ€ํ•œ ๋ถ„์ž๊ตฌ์กฐ์ธ DETDA๊ฐ€ ์˜ํ–ฅ์ด ์žˆ๋‹ค๊ณ  ํŒ๋‹จํ•˜์˜€๋‹ค. DETDA๊ฐ€ ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ์‹ ์žฅ๋ฅ  400%์˜ ์—ฐ์งˆํ˜•ํƒœ์—์„œ ๊ฒฝ์งˆํ˜•ํƒœ๋กœ ๋ฐ”๋€Œ์—ˆ๊ธฐ ๋•Œ๋ฌธ์— ์‹ ์žฅ๋ฅ ์ด ์ค„์–ด๋“  ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

Fig. 8

Percent elongation test results

/Resources/kci/JKCI.2017.29.2.131/images/Figure_CONCRETE_29_02_01_F8.jpg

4.2 ๋ถ€์ฐฉ ์„ฑ๋Šฅ ํ‰๊ฐ€

๋‚ด์ง„๋ณด๊ฐ•์šฉ STPU์— ๋Œ€ํ•˜์—ฌ ์†Œํฌ์ œ๋ฅผ ์ฒจ๊ฐ€ํ•œ ๊ฒฝ์šฐ์™€ ์ฒจ๊ฐ€ํ•˜์ง€ ์•Š์€ ๊ฒฝ์šฐ์— ๋Œ€ํ•œ ๋ถ€์ฐฉ๊ฐ•๋„์˜ ๊ฒฐ๊ณผ ๊ทธ๋ž˜ํ”„๋ฅผ Fig. 9์— ๋‚˜ํƒ€๋ƒˆ๋‹ค. Step 1, 2์˜ ๋ถ€์ฐฉ๊ฐ•๋„๋Š” ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 12 MPa์ด๋ฉฐ ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 8 MPa ์ดํ•˜๋กœ ๋–จ์–ด์กŒ๋‹ค. Step 3, 4์˜ ๋ถ€์ฐฉ๊ฐ•๋„๋Š” ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 12 MPa์ด๋ฉฐ ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 9 MPa ์ดํ•˜๋กœ ๋–จ์–ด์กŒ๋‹ค. Step 5์˜ ๋ถ€์ฐฉ๊ฐ•๋„๋Š” ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 13 MPa์ด๋ฉฐ ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 10 MPa ์ดํ•˜๋กœ ๋–จ์–ด์กŒ๋‹ค. Step 6์˜ ๋ถ€์ฐฉ๊ฐ•๋„๋Š” ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 14 MPa์ด๋ฉฐ ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 9 MPa ์ดํ•˜๋กœ ๋–จ์–ด์กŒ๋‹ค. ์†Œํฌ์ œ๋ฅผ ์‚ฌ์šฉํ•˜์˜€์„ ๊ฒฝ์šฐ 3๏ฝž5 MPa์ •๋„์˜ ๋ถ€์ฐฉ๊ฐ•๋„๊ฐ€ ๋†’๊ฒŒ ์ธก์ •๋˜์—ˆ์Œ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ ๋‹จ๊ณ„๋ณ„ ๋ฐฐํ•ฉ์ด ๋‹ฌ๋ผ์ง์— ๋”ฐ๋ผ ๋ถ€์ฐฉ๊ฐ•๋„๋Š” ํฐ ์ฐจ์ด๊ฐ€ ์—†๋‹ค๋Š” ๊ฒƒ์„ ํ™•์ธํ•˜์˜€๋‹ค.

Fig. 9

Pull-off test results

/Resources/kci/JKCI.2017.29.2.131/images/Figure_CONCRETE_29_02_01_F9.jpg

4.3 Shore ๊ฒฝ๋„ ํ‰๊ฐ€

Fig. 10์€ ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„์— ๋Œ€ํ•˜์—ฌ ์†Œํฌ์ œ๋ฅผ ์ฒจ๊ฐ€ํ•œ ๊ฒฝ์šฐ์™€ ์ฒจ๊ฐ€ํ•˜์ง€ ์•Š์€ ๊ฒฝ์šฐ์— ๋Œ€ํ•œ Shore ๊ฒฝ๋„(D)๋ฅผ ์ธก์ •ํ•œ ๊ฒฐ๊ณผ ๊ทธ๋ž˜ํ”„์ด๋‹ค. Step 1, 2์˜ Shore ๊ฒฝ๋„๋Š” ์†Œํฌ์ œ ์‚ฌ์šฉ ์œ ๋ฌด๋ฅผ ๋– ๋‚˜ ๊ฐ๊ฐ 65, 67์ •๋„์ด๋ฉฐ, Step 3์˜ Shore ๊ฒฝ๋„๋Š” ์†Œํฌ์ œ ์‚ฌ์šฉ ์‹œ 68 ์ด์ƒ์ด๊ณ  ์‚ฌ์šฉํ•˜์ง€ ์•Š์•˜์„ ๊ฒฝ์šฐ 67๋กœ ๋–จ์–ด์กŒ๋‹ค. Step 4๋ถ€ํ„ฐ 6๊นŒ์ง€์˜ Shore ๊ฒฝ๋„๋Š” ์†Œํฌ์ œ ์‚ฌ์šฉ ์œ ๋ฌด๋ฅผ ๋– ๋‚˜ ๊ฐ๊ฐ 65, 70, 70 ์ •๋„์ด๋‹ค. ์กฐ๋ฐ€ํ•œ ๋ถ„์ž๊ตฌ์กฐ์ธ DETDA, Secondary Amine, Polyetheramine์˜ ํ•จ์œ ๋Ÿ‰์ด ๋ณตํ•ฉ์ ์œผ๋กœ ๋ฐฐํ•ฉ๋จ์— ๋”ฐ๋ผ ๊ฒฝ๋„์— ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š” ๊ฒƒ์„ ํ™•์ธํ•˜์˜€๋‹ค. ํŠนํžˆ Secondary Amine ํ•จ์œ ๋Ÿ‰์ด ๊ฐ€์žฅ ์ ์€ Step 5, 6์—์„œ ๊ฐ€์žฅ ๋†’์€ ๊ฒฝ๋„๊ฐ€ ๋ฐœ์ƒ๋˜์—ˆ๊ณ  Polyetheramine๊ฐ€ ์ฒจ๊ฐ€๋˜๋ฉด์„œ ๊ฒฝ๋„๊ฐ€ ๋†’์•„์ง€๋Š” ๊ฒƒ์„ ํ™•์ธํ•˜์˜€๋‹ค.

Fig. 10

Hardness test results

/Resources/kci/JKCI.2017.29.2.131/images/Figure_CONCRETE_29_02_01_F10.jpg

4.4 FTPU์™€ ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„์˜ ์žฌ๋ฃŒ ํŠน์„ฑ

๋ณธ ์—ฐ๊ตฌ์—์„œ Step 6์— ํ•ด๋‹นํ•˜๋Š” STPU๋ฅผ ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„๋กœ ์„ ํƒํ•˜์˜€๋‹ค. ๊ธฐ์กด FTPU์™€ ๊ฑฐ์˜ ์œ ์‚ฌํ•œ ์กฐ์„ฑ๋น„๋ฅผ ๊ฐ€์ง€๊ณ  ์žˆ๋Š” Step 1๋ณด๋‹ค ์šฐ์ˆ˜ํ•œ ๋ฌผ๋ฆฌ์  ์„ฑ์งˆ์„ ๋‚˜ํƒ€๋‚ด์—ˆ์œผ๋ฉฐ, Table 3์— ๊ฒฐ๊ณผ ๊ฐ’์„ ์ •๋ฆฌํ•˜์—ฌ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. STPU๋Š” ์ง€์†์‹œ๊ฐ„ 20์ดˆ, ์ธ์žฅ๊ฐ•๋„ 26 MPa, ๊ฒฝ๋„ 70, ๋ถ€์ฐฉ๊ฐ•๋„ 14 MPa, ์‹ ์žฅ๋ฅ  150%๋กœ FTPU์™€ ๋น„๊ตํ•ด ๋ณผ ๋•Œ ์ง€์†์‹œ๊ฐ„ 200%, ์ธ์žฅ๊ฐ•๋„ 144%, ๊ฒฝ๋„ 107%, ๋ถ€์ฐฉ๊ฐ•๋„ 116%๋กœ ํ–ฅ์ƒ๋œ ์„ฑ๋Šฅ์„ ๋ฐœํœ˜ํ•˜์˜€์œผ๋ฉฐ, STPU์˜ ์‹ ์žฅ๋ฅ ์€ 150%๋กœ FTPU์˜ ์‹ ์žฅ๋ฅ ๋ณด๋‹ค 62.5% ๊ฐ์†Œ๋œ ์„ฑ๋Šฅ์„ ๋ฐœํœ˜ํ•˜์˜€๋‹ค.

Table 3 Material properties of polyurea

/Resources/kci/JKCI.2017.29.2.131/images/Table_CONCRETE_29_02_01_T3.jpg

5. ๊ฒฐ    ๋ก 

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” FTPU์˜ ์กฐ์„ฑ๋น„๋ฅผ ๋ณ€ํ™”์‹œ์ผœ ์ตœ์ ์˜ ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„๋ฅผ ๊ฐœ๋ฐœํ•˜๊ณ  ์žฌ๋ฃŒ ์„ฑ๋Šฅ์„ ์‹คํ—˜์ ์œผ๋กœ ๊ฒ€์ฆํ•˜์˜€๋‹ค.

1)๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„๋Š” ์ธ์žฅ๊ฐ•๋„ 26 MPa, ์‹ ์žฅ๋ฅ  150%๋กœ FTPU์˜ ์ธ์žฅ๊ฐ•๋„๋ณด๋‹ค ์•ฝ 1.44๋ฐฐ ํ–ฅ์ƒ๋œ ์„ฑ๋Šฅ์„ ๋ฐœํœ˜ํ•˜์˜€์œผ๋ฉฐ, ์‹ ์žฅ๋ฅ ์˜ ๊ฒฝ์šฐ ์•ฝ 0.62๋ฐฐ ๊ฐ์†Œ๋œ ์„ฑ๋Šฅ์„ ๋ฐœํœ˜ํ•˜์˜€๋‹ค. ๋†’์€ ์ธ์žฅ๊ฐ•๋„(25 MPa ์ด์ƒ)์™€ ๋‚ฎ์€ ์‹ ์žฅ๋ฅ (150% ์ดํ•˜)์„ ๋ชฉํ‘œ๋กœ ํ•œ ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„๋ฅผ ๊ฐœ๋ฐœํ•˜์˜€๋‹ค.

2)๋˜ํ•œ, ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„๋Š” ์ง€์†์‹œ๊ฐ„ 20์ดˆ, ๊ฒฝ๋„ 70, ๋ถ€์ฐฉ๊ฐ•๋„ 14 MPa๋กœ FTPU๋ณด๋‹ค ์ง€์†์‹œ๊ฐ„ 2๋ฐฐ, ๊ฒฝ๋„ 1.07๋ฐฐ, ๋ถ€์ฐฉ๊ฐ•๋„ 1.16๋ฐฐ ํ–ฅ์ƒ๋œ ์„ฑ๋Šฅ์„ ๋ฐœํœ˜ํ•˜์˜€๋‹ค.

3)๊ฒฝํ™”์ œ์˜ ๊ตฌ์„ฑ์š”์†Œ์ธ ์†Œํฌ์ œ์˜ ์‚ฌ์šฉ์— ๋”ฐ๋ผ ์ธ์žฅ๊ฐ•๋„์˜ ๊ฒฝ์šฐ 1๏ฝž2 MPa์ •๋„, ๋ถ€์ฐฉ๊ฐ•๋„์˜ ๊ฒฝ์šฐ 3๏ฝž5 MPa ์ •๋„๋กœ ๋†’๊ฒŒ ์ธก์ •๋˜๋Š” ๊ฒƒ์„ ํ™•์ธํ•  ์ˆ˜ ์žˆ๊ณ , ์ง€์†์‹œ๊ฐ„, ์‹ ์žฅ๋ฅ , ๊ฒฝ๋„์—๋Š” ์˜ํ–ฅ์„ ๋ฏธ์น˜์ง€ ์•Š๋Š” ๊ฒƒ์„ ํ™•์ธํ•˜์˜€๋‹ค.

4)๋ถ€์ฐฉ๊ฐ•๋„๋ฅผ ์ œ์™ธํ•œ ์ง€์†์‹œ๊ฐ„, ์ธ์žฅ๊ฐ•๋„, ์‹ ์žฅ๋ฅ , Shore ๊ฒฝ๋„๋ถ€๋ถ„์—์„œ ํด๋ฆฌ์šฐ๋ ˆ์•„ ๊ฒฝํ™”์ œ ๋ฐฐํ•ฉ์˜ ๊ตฌ์„ฑ์š”์†Œ ์ค‘ DETDA์˜ ํ•จ์œ ๋Ÿ‰๊ณผ Secondary Amine์˜ ํ•จ์œ ๋Ÿ‰์ด ํฐ ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š” ๊ฒƒ์„ ํ™•์ธํ•˜์˜€๋‹ค. ๋˜ํ•œ, Polyetheramine ์—ญ์‹œ ์ธ์žฅ๊ฐ•๋„ ๋ฐ Shore ๊ฒฝ๋„๋ฅผ ํ–ฅ์ƒ์‹œํ‚ค๋Š” ์—ญํ• ์„ ํ•˜๊ณ  ์žˆ๋Š” ๊ฒƒ์„ ํ™•์ธํ•˜์˜€๋‹ค.

5)๋ณธ ์—ฐ๊ตฌ์—์„œ ๋ชฉํ‘œํ•œ 25 MPa ์ด์ƒ์˜ ์ธ์žฅ๊ฐ•๋„์™€ 150% ์ดํ•˜์˜ ์‹ ์žฅ๋ฅ ์„ ๋งŒ์กฑํ•˜๋Š” ๋‚ด์ง„๋ณด๊ฐ•์šฉ ํด๋ฆฌ์šฐ๋ ˆ์•„๋Š” ๊ธฐ์กด์˜ FRP ํ‘œ๋ฉด ๋ถ€์ฐฉ ๊ณต๋ฒ•์„ ๋Œ€์•ˆํ•  ์ˆ˜ ์žˆ๋Š” ์žฌ๋ฃŒ๋ผ๊ณ  ์‚ฌ๋ฃŒ๋˜๋ฉฐ, ์—ดํ™”๋œ RC ๊ธฐ๋‘ฅ๊ตฌ์กฐ๋ฌผ์— ํด๋ฆฌ์šฐ๋ ˆ์•„ ๋‹จ์ผ ๋ณด๊ฐ• ๋˜๋Š” ์—ํญ์‹œ ํŒŒ๋‹จ์„ ๋ฐฉ์ง€ํ•˜๊ธฐ ์œ„ํ•œ FRP ํ•จ์นจ ํ›„ ๊ทธ ์œ„์— ํด๋ฆฌ์šฐ๋ ˆ์•„๋ฅผ ๋„ํฌํ•˜๋Š” ๋ณตํ•ฉ ๋ณด๊ฐ•์€ RC ๊ธฐ๋‘ฅ์˜ ๊ตฌ์†๋ ฅ์„ ์ฆ์ง„ ์‹œํ‚ค๊ฑฐ๋‚˜ RC ๊ตฌ์กฐ๋ฌผ์˜ ์—ฐ์„ฑ์„ ํ™•๋ณดํ•˜์—ฌ ์ง€์ง„ํ•˜์ค‘์— ๋Œ€ํ•œ ๋‚ด์ง„์„ฑ๋Šฅ์„ ์ตœ๋Œ€๋กœ ํ•  ์ˆ˜ ์žˆ์„ ๊ฒƒ์ด๋ผ๊ณ  ์‚ฌ๋ฃŒ๋œ๋‹ค.

Acknowledgements

์ด ์—ฐ๊ตฌ๋Š” ๊ตญํ† ๊ตํ†ต๋ถ€(๊ตญํ† ๊ตํ†ต๊ณผํ•™๊ธฐ์ˆ ์ง„ํฅ์›) 2015๋…„ ๊ตญํ† ๊ตํ†ต๊ธฐ์ˆ ์‚ฌ์—…ํ™”์ง€์›์‚ฌ์—… โ€˜๊ธฐ๋‘ฅ๋ถ€์žฌ์˜ ๋‚ด์ง„ ์„ฑ๋Šฅ ๋ฐ ๋‚ด๊ตฌ์„ฑ ๊ทน๋Œ€ํ™”๋ฅผ ์œ„ํ•œ PU Spray ๋ณด์ˆ˜ ๋ณด๊ฐ• ๊ณต๋ฒ•์˜ ์‹ค์šฉํ™”(15TBIP-CO74206-02)โ€™ ์—ฐ๊ตฌ๋‹จ์„ ํ†ตํ•ด ์ˆ˜ํ–‰๋˜์—ˆ์œผ๋ฉฐ, ์›์ž๋ ฅ์•ˆ์ „์œ„์›ํšŒ์˜ ์žฌ์›์œผ๋กœ ํ•œ๊ตญ์›์ž๋ ฅ์•ˆ์ „์žฌ๋‹จ์˜ ์ง€์›์„ ๋ฐ›์•„ ์ˆ˜ํ–‰ํ•œ ์›์ž๋ ฅ์•ˆ์ „์—ฐ๊ตฌ๊ฐœ๋ฐœ์‚ฌ์—…์˜ ์—ฐ๊ตฌ๊ฒฐ๊ณผ์ž…๋‹ˆ๋‹ค. (No.1403010) ์—ฐ๊ตฌ์ง€์›์— ๊ฐ์‚ฌํ•ฉ๋‹ˆ๋‹ค.

References

1 
KMA, Korea Meteorological Administration, Earthquake, http://www.kma.go.kr/mini/earthquake/main.jspGoogle Search
2 
Woo, W.T., Kown, Y.H., and Chung, L., โ€œEvaluation of the Seismic Performance of Existing Building Structuresโ€, Journal of the earthquake engineering society of Korea, Vol.4, No.4, 2000, pp.105-110.Google Search
3 
Chung, L., Park, T.W., and Lee, S.G., โ€œRetrofitting Effects on Seismic Resistance Capacity of Reinforced Concrete Framed Structureโ€, Journal of the Architectural Institute of Korea, Vol. 20, No. 9, 2004, pp. 37-44.Google Search
4 
Kim, T.H., Seong, D.J., and Shin, H.M., โ€œSeismic Performance Assessment of Hollow Reinforced Concrete and Prestressed Concrete Bridge Columnsโ€, International Journal of Concrete Structures and Materials, Vol.6, No.3, 2012, pp.165-176.DOI
5 
Heo, Y.A., and Kunnath, S.K., โ€œDamage-Based Seismic Performance Evaluation of Reinforced Concrete Framesโ€, International Journal of Concrete Structures and Materials, Vol.7, No.3, 2013, pp.175-182.DOI
6 
Kim, S.D., โ€œSeismic Evaluation and Retrofit of Low-rise RC Buildings in Koreaโ€, Ministry of Land Infrastructure and Transport, Business of Research and Development Annual Report, 2002.Google Search
7 
Chen, J.F., and Teng, J.G., โ€œAnchorage Strength Models for FRP and Steel Plates Bonded to Concreteโ€, Journal of Structural Engineering, Vol.127, No.7, 2001, pp.784-791.DOI
8 
Bonacci, J.F. and Maalej, M., โ€œBehavioral Trends of RC Beams Strengthened with Externally Bonded FRPโ€, Journal of Composites for Construction, Vol.5, No.2, 2001, pp.102-113.DOI
9 
Lee, S.K., Chen, Z.F., Ng, M., Tang, J.M., Wan, L. L., Liu, M., and Lee, L., โ€œEvaluation of CFRP, GFRP and BFRP Material Systems for the Strengthening of RC Slabsโ€, Journal of Reinforced Plastics and Composites, 2008, pp.1233-1243Google Search
10 
Kang, T.H.K., Kim, W.S., Ha, S.S., and Choi, D.U., โ€œHybrid Effects of Carbon-Glass FRP Sheets in Combination with or without Concrete Beamsโ€, International Journal of Concrete Structures and Materials, Vol.8, No.1, pp.27-41.Google Search
11 
Lorenzis, L.D., and Teng, J.G., โ€œNear-surface Mounted FRP Reinforcement: An Emerging Technique for Strengthening Structuresโ€, Composites Part B: Engineering, Vol.38, No.2, 2007, pp.119-143.DOI
12 
Kang, T.H.K., and Ibrahim Ary, M., โ€œShear- Strengthening of Reinforced & Prestressed Concrete Beams Using FRP: Part II - Experimental Investigationโ€, International Journal of Concrete Structures and Materials, Vol.6, No.1, 2012, pp.49-57.DOI
13 
Seo, S.Y., and Kim, M.S., โ€œBond Strength of Near Surface-Mounted FRP Plate in Concrete Corresponding to Space and Bond Lengthโ€, Journal of the Korea Concrete institute, Vol.25, No.1, 2013, pp.37-43.Google Search
14 
Hong, S.N., Park, J.M., Park, S.K., Park, J.S., and Park, Y.H., โ€œAn Experimental Study on Flexural Behavior of RC Beams Strengthened with Near Surface Mounted Prestressed FRPโ€, Journal of the Korea Concrete institute, Vol.18, No.6, 2006, pp.737-742.Google Search
15 
Jang, H.N. and Lee, J.Y., โ€œCase Study of Earthquake Damage in Korea and Other Countriesโ€, Journal of the Korean Society of Civil Engineers, Vol.55, No.4, 2007, pp.133-139.Google Search
16 
Rodrigues, H., Varum, H., Arรชde, A., and Costa, A.G., โ€œBehaviour of Reinforced Concrete Column Under Biaxial Cyclic Loading-state of the Artโ€, International Journal of Advanced Structural Engineering, Vol.5, No.1, 2013, pp. 1-12.DOI
17 
Kim, S.B., Kim, J.H.J., Choi, H.S., and Heo, G., โ€œDevelopment and Applicability Evaluation of High Performance Poly-urea for RC Construction Reinforcementโ€, Journal of the Korean Society of Civil Engineers, Vol.30, No.2, 2010, pp.169-176.Google Search
18 
Kim, J.H.J., Park, J.C., Lee, S.W., and Kim, S.B., โ€œEvaluation of Strengthening Performance of Stiff Type Polyurea Retrofitted RC Slab Based on Attachment Procedureโ€, Journal of the Korea Concrete Institute, Vol.23, No.4, 2011, pp.511-520.DOI
19 
Park, J.C., Lee, S.W., Kim, S.B., and Kim, J.H.J., โ€œPerformance Evaluation of RC Slabs Strengthened by Stiff Type PolyUreaโ€, Journal of the Korean Society of Civil Engineers, Vol.31, No.6, 2011, pp.457-464.Google Search
20 
Lamba, N.M.K., Woodhouse, K.A., and Cooper, S.L., โ€œPolyureathanes in Biomedical Applicationsโ€, CRC PRESS, United States of America, 1998, pp.14-23.Google Search
21 
Ha, J.H., Yi, N.H., Cho, Y.G., and Kim, J.H.J., โ€œExperimental Study on Bond Behavior of Retrofit materials by Bond-Shear Testโ€, Journal of the Korea Concrete institute, Vol.24, No.1, 2012, pp.45-52.Google Search
22 
Greene, C.E., and Myers, J.J., โ€œFlexural and Shear Behavior of Reinforced Concrete Members Strengthened with a Discrete Fiber-reinforced Polyurea Systemโ€, Journal of Composites for Construction, Vol.17, No.1, 2012, pp.108-116.DOI