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์ดˆ๊ณ ์„ฑ๋Šฅ ์ฝ˜ํฌ๋ฆฌํŠธ, ๊ฐ•์„ฌ์œ , ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„, ์••์ถ•๊ฐ•๋„, ํƒ„์„ฑ๊ณ„์ˆ˜
ultra-high performance concrete, steel fiber, stress-strain relationship, compressive strength, modulus of elasticity

  • 1. ์„œ ๋ก 

  • 2. ํ˜„ํ–‰ ์„ค๊ณ„๊ธฐ์ค€

  • 3. ์‹คํ—˜ ํ”„๋กœ๊ทธ๋žจ

  •   3.1 ์‚ฌ์šฉ์žฌ๋ฃŒ

  •   3.2 ์‹คํ—˜๋ฐฉ๋ฒ•

  •   3.3 ์ดˆ์ŒํŒŒ ์†๋„

  • 4. ์‹คํ—˜ ๊ฒฐ๊ณผ

  •   4.1 ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„

  •   4.2 ํŒŒ๊ดด๋ชจ๋“œ

  •   4.3 ์ฒด์ ๋ณ€ํ˜•

  •   4.4 ํƒ„์„ฑ๊ณ„์ˆ˜

  • 5. ๊ฒฐ๊ณผ ๋ถ„์„

  •   5.1 ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„

  •   5.2 ํƒ„์„ฑ๊ณ„์ˆ˜

  • 6. ๊ฒฐ ๋ก 

1. ์„œ    ๋ก 

ํ•˜์ด๋ธŒ๋ฆฌ๋“œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ดˆ๊ณ ์„ฑ๋Šฅ ์ฝ˜ํฌ๋ฆฌํŠธ(Hybrid steel fiber reinforced ultra-high performance concrete, ์ดํ•˜ UHPC)๋Š” ์••์ถ•๊ฐ•๋„๊ฐ€ ๋งค์šฐ ๋†’์€ ์ดˆ๊ณ ์„ฑ๋Šฅ ์‹œ๋ฉ˜ํŠธ ๋ณตํ•ฉ์ฒด(Ultra-high performance cementitioius composites)์— ๊ธธ์ด๊ฐ€ ์„œ๋กœ ๋‹ค๋ฅธ ๊ฐ•์„ฌ์œ ๋ฅผ ํ˜ผํ•ฉํ•˜์—ฌ ์••์ถ•๊ฐ•๋„๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ์ธ์žฅ๊ฐ•๋„์™€ ํœจ์ธ์„ฑ ๋“ฑ์„ ํ–ฅ์ƒ์‹œํ‚จ ์‹ ๊ฐœ๋… ๊ฑด์„ค์žฌ๋ฃŒ์ด๋‹ค. ๊ฐœ๋ฐœ๋œ UHPC๋Š” ๊ธฐ์กด์˜ ์ทจ์„ฑํŒŒ๊ดด๋ฅผ ๋ณด์ด๋Š” ์ผ๋ฐ˜ ์ฝ˜ํฌ๋ฆฌํŠธ์™€๋Š” ๋‹ฌ๋ฆฌ ์ตœ๋Œ€ ๊ฐ•๋„ ๋„๋‹ฌ ์ดํ›„ ํŒŒ๊ดด ์‹œ๊นŒ์ง€ ์šฐ์ˆ˜ํ•œ ์—ฐ์„ฑ๋Šฅ๋ ฅ์„ ๋ณด์ธ๋‹ค. ์ด ์žฌ๋ฃŒ๋Š” ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ผ 10MPa ์ด์ƒ์˜ ๋†’์€ ์ธ์žฅ๊ฐ•๋„๋ฅผ ๋ณด์ด๋ฉฐ, ์••์ถ•๊ฐ•๋„๋Š” 200MPa ์ด์ƒ, ๊ทธ๋ฆฌ๊ณ  ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” 40GPa ์ด์ƒ ๋ฐœํ˜„๋˜๋Š” ๊ฒƒ์œผ๋กœ ์•Œ๋ ค์ ธ ์žˆ๋‹ค.1-3) ์ด์™€ ๊ฐ™์ด ๊ฐ•๋„์™€ ์ธ์„ฑ ์ธก๋ฉด์—์„œ ํƒ์›”ํ•œ ์„ฑ๋Šฅ์„ ๋ณด์ด๋Š” UHPC๋ฅผ ๊ตฌ์กฐ๋ฌผ์— ํšจ์œจ์ ์œผ๋กœ ์‚ฌ์šฉํ•˜๊ธฐ ์œ„ํ•ด์„œ๋Š” ์žฌ๋ฃŒ์˜ ํŠน์„ฑ์„ ๋ช…ํ™•ํžˆ ๊ทœ๋ช…ํ•  ํ•„์š”๊ฐ€ ์žˆ๋‹ค. ํ˜„ํ–‰ ์„ค๊ณ„๊ธฐ์ค€์—์„œ๋Š” UHPC์˜ ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„์™€ ํƒ„์„ฑ๊ณ„์ˆ˜, ๊ทธ๋ฆฌ๊ณ  ๊ทนํ•œ ๋ณ€ํ˜•๋ฅ  ๋“ฑ์ด ์ œ์‹œ๋˜์–ด ์žˆ์ง€๋งŒ, ์ด๋Š” ๋ชจ๋‘ ํŠน์ • ์••์ถ•๊ฐ•๋„ ํŠน์„ฑ๊ฐ’์„ ๊ฐ€์ง„ UHPC๋ฅผ ๋Œ€์ƒ์œผ๋กœ ์ œ์‹œ๋œ ๊ฒƒ์œผ๋กœ์จ, ๋‹ค์–‘ํ•œ ๊ฐ•๋„์˜ UHPC์˜ ์••์ถ•๊ฑฐ๋™์— ๋Œ€ํ•œ ์••์ถ•ํŠน์„ฑ์œผ๋กœ ๊ทœ์ •ํ•˜๊ธฐ์—๋Š” ํ•œ๊ณ„๊ฐ€ ์žˆ๋‹ค.4-5) ๋”ฐ๋ผ์„œ, 100MPa ์ด์ƒ์ธ ๋‹ค์–‘ํ•œ ์••์ถ•๊ฐ•๋„๋ฅผ ๊ฐ€์ง€๋Š” UHPC์˜ ์••์ถ•๊ฑฐ๋™ ํŠน์„ฑ์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๊ฐ€ ํ•„์š”ํ•˜๋‹ค.

๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฑฐ๋™์— ๊ด€ํ•œ ์—ฐ๊ตฌ๋Š” ๋งŽ์€ ์—ฐ๊ตฌ์ž๋“ค์— ์˜ํ•ด ์ˆ˜ํ–‰๋˜์—ˆ๋‹ค. ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„๋Š” ๊ฐ•์„ฌ์œ  ๋ถ€ํ”ผ๋น„, ์ค‘๋Ÿ‰๋น„, ๊ฐ•์„ฌ์œ ์˜ ํ˜•์ƒ ๋“ฑ ๋งŽ์€ ๋ณ€์ˆ˜๋“ค์˜ ์˜ํ–ฅ์„ ๋ฐ›๋Š”๋‹ค. ์••์ถ•๊ฐ•๋„๊ฐ€ 35~100MPa์ธ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์— ๋Œ€ํ•œ ๊ธฐ์กด ์—ฐ๊ตฌ๋“ค์— ๋”ฐ๋ฅด๋ฉด, ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ์••์ถ•๊ฐ•๋„๋Š” ๋‹ค์†Œ ์ฆ๊ฐ€ํ•˜๋ฉฐ, ์ด๋Ÿฌํ•œ ํ˜„์ƒ์€ ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ๋ณด๋‹ค๋Š” ๊ฐ•์„ฌ์œ ์˜ ๋ถ€ํ”ผ๋น„์™€ ํ˜•์ƒ๋น„๋กœ ํ‘œํ˜„๋˜๋Š” ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜(Reinforcement Index, ์ดํ•˜ RI)๊ฐ€ ์••์ถ•๊ฐ•๋„ ํ–ฅ์ƒ์— ๋” ํฐ ์˜ํ–ฅ์„ ๋ผ์น˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค.6-11) ์—ฌ๊ธฐ์„œ, ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜(RI)๋Š” /Resources/kci/JKCI.2016.28.2.213/images/PICB910.gif๋กœ ์ •์˜๋˜๋ฉฐ, /Resources/kci/JKCI.2016.28.2.213/images/PICB9CC.gif๋Š” ๋ถ€ํ”ผ๋น„๋กœ ํ‘œํ˜„๋œ ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ , /Resources/kci/JKCI.2016.28.2.213/images/PICB9CD.gif์™€ /Resources/kci/JKCI.2016.28.2.213/images/PICB9DE.gif๋Š” ๊ฐ๊ฐ ๊ฐ•์„ฌ์œ ์˜ ๊ธธ์ด์™€ ์ง๊ฒฝ์„ ๋‚˜ํƒ€๋‚ธ๋‹ค. Kang et al.1)์€ ์••์ถ•๊ฐ•๋„๊ฐ€ 48.3~235.1MPa์ธ ์ดˆ๊ณ ์„ฑ๋Šฅ ์‹œ๋ฉ˜ํŠธ ๋ณตํ•ฉ์ฒด(UHPCC)์˜ ๊ฐ•์„ฌ์œ  ํ˜ผ์ž… ํšจ๊ณผ์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๋ฅผ ํ†ตํ•ด ๊ฐ•์„ฌ์œ ๋ณด๊ฐ•์— ๋”ฐ๋ผ ์••์ถ•๊ฐ•๋„๊ฐ€ ์ฆ๊ฐ€ํ•˜๋ฉฐ ํŠนํžˆ, ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜๊ฐ€ ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ์••์ถ•๊ฐ•๋„๊ฐ€ ์ฆ๊ฐ€ํ•œ๋‹ค๊ณ  ๋ณด๊ณ ํ•˜์˜€๋‹ค. ๊ทธ๋ฆฌ๊ณ  ์••์ถ•๊ฐ•๋„๋Š” ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜์— ๋Œ€ํ•ด ์ผ์ •ํ•œ ์„ ํ˜•๊ด€๊ณ„๋ฅผ ๊ฐ€์ง„๋‹ค๊ณ  ํ•˜์˜€์œผ๋ฉฐ ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ํ† ๋Œ€๋กœ ์••์ถ•๊ฐ•๋„๊ฐ€ 200MPa ์ด์ƒ์ธ UHPCC์— ์ ์šฉ๊ฐ€๋Šฅํ•œ ์••์ถ•๊ฐ•๋„์™€ ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜์™€์˜ ๊ด€๊ณ„์‹์„ ๋„์ถœํ•˜์˜€๋‹ค. ์ดํ›„ Kang et al.2)์€ UHPCC์˜ ์••์ถ•์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„๋ฅผ ์ œ์‹œํ•˜์˜€์œผ๋ฉฐ, ๊ฐ•์„ฌ์œ ๋ณด๊ฐ•ํšจ๊ณผ๋Š” ์••์ถ•๊ฐ•๋„์™€ ๊ทธ ๋•Œ์˜ ๊ทนํ•œ๋ณ€ํ˜•๋ฅ  ๋ฐ ํƒ„์„ฑ๊ณ„์ˆ˜์— ์˜ํ–ฅ์„ ๋ฏธ์นœ๋‹ค๊ณ  ํ•˜์˜€๋‹ค. ๋น„๋ก ๊ตญ๋‚ด ์—ฐ๊ตฌ์ง„๋“ค์— ์˜ํ•ด ์••์ถ•๊ฐ•๋„๊ฐ€ 200MPa์— ์ด๋ฅด๋Š” UHPC์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๊ฐ€ ์ˆ˜ํ–‰๋˜๊ธด ํ–ˆ์ง€๋งŒ, ์••์ถ•๊ฐ•๋„๊ฐ€ 100MPa ์ด์ƒ์ธ UHPC์˜ ์••์ถ•๊ฑฐ๋™์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๋Š” ์ƒ๋Œ€์ ์œผ๋กœ ๋ฏธ์ง„ํ•œ ์‹ค์ •์ด๋‹ค. ๊ฒŒ๋‹ค๊ฐ€ UHPC์— ๋Œ€ํ•œ ์„ค๊ณ„์ง€์นจ์— ์••์ถ•๋ ฅ์„ ๋ฐ›๋Š” UHPC์˜ ์žฌ๋ฃŒ์  ํŠน์„ฑ๋“ค์ด ์ œ์‹œ๋˜์–ด ์žˆ์ง€๋งŒ, ์‹คํ—˜์—ฐ๊ตฌ๋ฅผ ํ†ตํ•ด ์ง€์นจ์—์„œ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š” ์„ค๊ณ„์ง€์นจ์ด ๊ฒ€์ฆ๋œ ๋ฐ”๊ฐ€ ์—†๋‹ค.

๋”ฐ๋ผ์„œ, ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ํ•˜์ด๋ธŒ๋ฆฌ๋“œ ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋œ UHPC์˜ ์••์ถ•๊ฑฐ๋™์— ๋Œ€ํ•œ ์‹คํ—˜์—ฐ๊ตฌ๋ฅผ ํ†ตํ•ด ํ˜„ํ–‰ ์„ค๊ณ„๊ธฐ์ค€์—์„œ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š” ์••์ถ•์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„์˜ ์ ์šฉ๊ฐ€๋Šฅ์„ฑ์„ ์•Œ์•„๋ณด๊ณ , ์••์ถ•๊ฐ•๋„์™€ ํƒ„์„ฑ๊ณ„์ˆ˜ ๋“ฑ UHPC์˜ ์žฌ๋ฃŒํŠน์„ฑ์„ ์ œ์‹œํ•˜๊ณ ์ž ํ•œ๋‹ค.

2. ํ˜„ํ–‰ ์„ค๊ณ„๊ธฐ์ค€

๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ดˆ๊ณ ์„ฑ๋Šฅ ์ฝ˜ํฌ๋ฆฌํŠธ(UHPC)์— ๋Œ€ํ•œ ๊ตญยท๋‚ด์™ธ ์„ค๊ณ„๊ธฐ์ค€์—์„œ๋Š” ์••์ถ•๊ฐ•๋„ ํŠน์„ฑ๊ฐ’(/Resources/kci/JKCI.2016.28.2.213/images/PICB9EF.gif)์ด 180MPa์ธ UHPC์˜ ์••์ถ•์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„์™€ ํƒ„์„ฑ๊ณ„์ˆ˜ ๋“ฑ์ด ์ œ์‹œ๋˜์–ด ์žˆ๋‹ค. Fig. 1์€ AFGC-SETRA4)์™€ ์ดˆ๊ณ ์„ฑ๋Šฅ ์ฝ˜ํฌ๋ฆฌํŠธ K-UHPC ๊ตฌ์กฐ์„ค๊ณ„์ง€์นจ5)(์ดํ•˜ K-UHPC)์—์„œ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š” UHPC์˜ ์••์ถ•์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ์••์ถ•๊ฐ•๋„ ํŠน์„ฑ๊ฐ’์ด 180MPa์ธ UHPC๋Š” Fig. 1์—์„œ ๋ณด์ด๋Š” ๋ฐ”์™€ ๊ฐ™์ด ์„ค๊ณ„์••์ถ•๊ฐ•๋„(/Resources/kci/JKCI.2016.28.2.213/images/PICB9F0.gif)์— ๋„๋‹ฌํ•  ๋•Œ๊นŒ์ง€ ์„ ํ˜•๊ฑฐ๋™์„ ํ•˜๋ฉฐ, ์ตœ๋Œ€๊ฐ•๋„์— ๋„๋‹ฌ์ดํ›„ ๊ทนํ•œ๋ณ€ํ˜•๋ฅ ๊นŒ์ง€ ์ผ์ •ํ•œ ๊ฐ•๋„๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค. Table 1์€ ํ˜„ํ–‰ ์„ค๊ณ„๊ธฐ์ค€์—์„œ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š” UHPC์˜ ์••์ถ•์„ค๊ณ„ ์ฃผ์š” ํŠน์„ฑ์น˜๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. AFGC-SETRA์—์„œ๋Š” ์„ค๊ณ„์••์ถ•๊ฐ•๋„(/Resources/kci/JKCI.2016.28.2.213/images/PICBA00.gif)๋ฅผ /Resources/kci/JKCI.2016.28.2.213/images/PICBA11.gif๋กœ ๊ทœ์ •ํ•˜๊ณ  ์žˆ๋‹ค.4) ์—ฌ๊ธฐ์„œ, /Resources/kci/JKCI.2016.28.2.213/images/PICBA22.gif๋Š” 0.85, /Resources/kci/JKCI.2016.28.2.213/images/PICBA23.gif๋Š” ์ตœ๋Œ€ ์••์ถ•๊ฐ•๋„, ๊ทธ๋ฆฌ๊ณ  /Resources/kci/JKCI.2016.28.2.213/images/PICBA33.gif๋Š” ์•ˆ์ „์œจ(=1.5)์ด๋‹ค. ๊ทนํ•œ๋ณ€ํ˜•๋ฅ (/Resources/kci/JKCI.2016.28.2.213/images/PICBA44.gif)์€ ์••์ถ•๊ฐ•๋„ ํŠน์„ฑ์น˜๊ฐ€ 150MPa์—์„œ 250MPa์ธ UHPC๋ฅผ ๋Œ€์ƒ์œผ๋กœ ์ตœ๋Œ€์••์ถ•๊ฐ•๋„๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ๊ท ์—ด์ดํ›„์˜ ์ธ์žฅ์‘๋ ฅ์„ ๋ชจ๋‘ ๊ณ ๋ คํ•˜๊ณ  ์žˆ์œผ๋ฉฐ, ์„ค๊ณ„๋ฅผ ์œ„ํ•œ UHPC์˜ ๊ทนํ•œ๋ณ€ํ˜•๋ฅ ์„ 0.0027๋กœ ์ œ์‹œํ•˜๊ณ  ์žˆ๋‹ค. UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜(/Resources/kci/JKCI.2016.28.2.213/images/PICBA54.gif)๋Š” Fig. 1(a)์™€ ๊ฐ™์€ ๋ฐฉ๋ฒ•์œผ๋กœ ๊ตฌํ•  ์ˆ˜ ์žˆ๋‹ค. AFGC- SETRA์— ๋”ฐ๋ฅด๋ฉด, ์‹คํ—˜์„ ํ†ตํ•ด ๊ตฌํ•œ ์ตœ๋Œ€ ์••์ถ•๊ฐ•๋„(/Resources/kci/JKCI.2016.28.2.213/images/PICBA55.gif)์™€ ๊ทธ ๋•Œ์˜ ๋ณ€ํ˜•๋ฅ (/Resources/kci/JKCI.2016.28.2.213/images/PICBA66.gif)์˜ ๊ด€๊ณ„๋ฅผ ํ†ตํ•ด ํƒ„์„ฑ๊ณ„์ˆ˜๋ฅผ ๊ตฌํ•  ์ˆ˜ ์žˆ์œผ๋ฉฐ, ์ด๋Ÿฌํ•œ ๋ฐฉ์‹์œผ๋กœ ๊ตฌํ•œ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” Fig. 1(b)์™€ ๊ฐ™์ด ์••์ถ•๋ ฅ์„ ๋ฐ›๋Š” UHPC์˜ ์„ค๊ณ„ ์••์ถ•๋ณ€ํ˜•๋ฅ ์„ ๊ตฌํ•˜๋Š”๋ฐ ์‚ฌ์šฉํ•  ์ˆ˜ ์žˆ๋‹ค.4) AFGC-SETRA์—์„œ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š” ํƒ„์„ฑ๊ณ„์ˆ˜์˜ ์ œ์•ˆ๊ฐ’์€ 50GPa์ด๋‹ค.

/Resources/kci/JKCI.2016.28.2.213/images/Figure_CONCRETE_28_2_10_F1.jpg

Fig. 1 Constitutive law for design

K-UHPC์—์„œ๋Š” ํœจ๋ชจ๋ฉ˜ํŠธ ๋ฐ ํœจ๋ชจ๋ฉ˜ํŠธ์™€ ์ถ•์••๋ ฅ์„ ๋™์‹œ์— ๋ฐ›๋Š” ๋ถ€์žฌ์˜ ๊ทนํ•œ์ƒํƒœ์—์„œ์˜ ๋‹จ๋ฉด๋‚ด๋ ฅ ๊ฒ€ํ† ๋ฅผ ์œ„ํ•ด ์••์ถ•์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„๋ฅผ ์ œ์‹œํ•˜๊ณ  ์žˆ๋‹ค.5) ์„ค๊ณ„์••์ถ•๊ฐ•๋„๋Š” ์ถฉ๋ถ„ํ•œ ์‹คํ—˜์„ ํ†ตํ•ด ๋ณ€๋™์„ฑ์ด ๋น„๊ต์  ์ž˜ ํŒŒ์•…๋œ ์‹คํ—˜๊ฐ’๋“ค์„ ๋Œ€์ƒ์œผ๋กœ ๊ฒฐ์ •๋œ ์žฌ๋ฃŒ์ €๊ฐ๊ณ„์ˆ˜(/Resources/kci/JKCI.2016.28.2.213/images/PICBA86.gif=0.91)๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ /Resources/kci/JKCI.2016.28.2.213/images/PICBA97.gif๋ฅผ ์‚ฌ์šฉํ•œ๋‹ค. ์ด ๊ธฐ์ค€์—์„œ๋Š” ํƒ„์„ฑ๊ณ„์ˆ˜(/Resources/kci/JKCI.2016.28.2.213/images/PICBAA8.gif)๋Š” 45GPa ๊ทธ๋ฆฌ๊ณ  ๊ทนํ•œ๋ณ€ํ˜•๋ฅ (/Resources/kci/JKCI.2016.28.2.213/images/PICBAB8.gif)์€ 0.004๋กœ ์ œ์‹œํ•˜๊ณ  ์žˆ๋‹ค.

3. ์‹คํ—˜ ํ”„๋กœ๊ทธ๋žจ

3.1 ์‚ฌ์šฉ์žฌ๋ฃŒ

์ด ์—ฐ๊ตฌ์—์„œ ์‚ฌ์šฉ๋œ ํ•˜์ด๋ธŒ๋ฆฌ๋“œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ดˆ๊ณ ์„ฑ๋Šฅ ์ฝ˜ํฌ๋ฆฌํŠธ(์ดํ•˜ UHPC)๋Š” ๊ตต์€ ๊ณจ์žฌ๋ฅผ ์‚ฌ์šฉํ•˜์ง€ ์•Š๊ณ  ๊ธธ์ด๊ฐ€ 19mm์™€ 16mm์ธ ๊ฐ•์„ฌ์œ ๋ฅผ ํ˜ผ์ž…ํ•˜์—ฌ 160MPa ์ด์ƒ์˜ ๋†’์€ ์••์ถ•๊ฐ•๋„๋ฅผ ๋ณด์ธ๋‹ค. UHPC์˜ ์ œ์ž‘์„ ์œ„ํ•ด ๋ณดํ†ต ํฌํ‹€๋žœ๋“œ ์‹œ๋ฉ˜ํŠธ๊ฐ€ ์‚ฌ์šฉ๋˜์—ˆ์œผ๋ฉฐ, ๋ฐ˜์‘์„ฑ ๋ถ„์ฒด๋กœ ์ง€๋ฅด์ฝ”๋Š„(Zirconium)์„ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ์ž”๊ณจ์žฌ๋Š” ํ‰๊ท ์ž…๊ฒฝ 0.5mm ์ดํ•˜์˜ ๋ชจ๋ž˜๋ฅผ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ๋ฌผ-๊ฒฐํ•ฉ์žฌ๋น„๋Š” 0.2์ด๋ฉฐ, ์ถฉ๋ถ„ํ•œ ์œ ๋™์„ฑ์„ ํ™•๋ณดํ•˜๊ธฐ ์œ„ํ•ด ํด๋ฆฌ์นด๋ฅด๋ณธ์‚ฐ๊ณ„ ๊ณ ์„ฑ๋Šฅ ๊ฐ์ˆ˜์ œ๋ฅผ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ์‹œ๋ฉ˜ํŠธ์˜ ์ˆ˜ํ™”๋ฐ˜์‘์„ ํ™œ์„ฑํ™”์‹œํ‚ค๊ณ  ์ž…์ž๋“ค ์‚ฌ์ด์˜ ๊ณต๊ทน์„ ๋ฉ”์›Œ ์กฐ์ง์„ ์น˜๋ฐ€ํ•˜๊ฒŒ ๋งŒ๋“ค๊ธฐ ์œ„ํ•ด ํ‰๊ท ์ž…๊ฒฝ 10ฮผm์ด๊ณ  SiO2์˜ ํ•จ์œ ์œจ์ด 98%์ด์ƒ์ด๋ฉฐ, ๋ฐ€๋„๊ฐ€ 2.6g/cm3์ธ ์ถฉ์ „์žฌ(Filler)๊ฐ€ ์‚ฌ์šฉ๋˜์—ˆ๋‹ค. Table 2๋Š” ์‹œ๋ฉ˜ํŠธ์— ๋Œ€ํ•œ ๊ตฌ์„ฑ์žฌ๋ฃŒ์˜ ์ค‘๋Ÿ‰๋น„๋กœ ๋‚˜ํƒ€๋‚ธ UHPC์˜ ๋ฐฐํ•ฉ๋น„๋ฅผ ๋ณด์—ฌ์ค€๋‹ค.

Table 2 Mix proportion (weight ratio)

Water- binder

ratio

Cement

Zirconium

Filler

Fine

agg.

Water-

reducing admixture

0.2

1.0

0.25

0.3

1.1

0.02

UHPC ์ œ์ž‘์— ์‚ฌ์šฉ๋œ ๊ฐ•์„ฌ์œ ๋Š” ๊ธธ์ด๊ฐ€ 19mm์™€ 16mm์ธ ์ง์„ ํ˜• ๊ฐ•์„ฌ์œ ๊ฐ€ ๊ฐ๊ฐ ์‚ฌ์šฉ๋˜์—ˆ๋‹ค. ๊ฐ•์„ฌ์œ ์˜ ํ•ญ๋ณต๊ฐ•๋„๋Š” 2,500MPa, ์ง๊ฒฝ์€ 0.2mm, ๊ทธ๋ฆฌ๊ณ  ํ˜•์ƒ๋น„(/Resources/kci/JKCI.2016.28.2.213/images/PICBAD8.gif)๋Š” ๊ธธ์ด๊ฐ€ 19mm์ธ ๊ฒฝ์šฐ๋Š” 95, 16mm์ธ ๊ฒฝ์šฐ๋Š” 80์ด๋‹ค. ๊ธธ์ด๊ฐ€ ์„œ๋กœ ๋‹ค๋ฅธ ๊ฐ•์„ฌ์œ ๋Š” ์ „์ฒด ๋ถ€ํ”ผ๋น„์— ๋Œ€ํ•ด 2 (19mm) : 1 (16mm)์˜ ๋น„์œจ๋กœ ํ˜ผ์ž…ํ•˜์˜€์œผ๋ฉฐ, ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ฅธ UHPC์˜ ์••์ถ•๊ฑฐ๋™์„ ์•Œ์•„๋ณด๊ธฐ ์œ„ํ•ด ์ „์ฒด ๋ถ€ํ”ผ๋น„๋Š” 0.5%์—์„œ 2.0%๊นŒ์ง€ ์ ์šฉ๋˜์—ˆ๋‹ค. ๋”ฐ๋ผ์„œ ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜๋Š” /Resources/kci/JKCI.2016.28.2.213/images/PICBB37.gif๊ณผ ๊ฐ™์ด ๊ตฌํ•  ์ˆ˜ ์žˆ๋‹ค. ์—ฌ๊ธฐ์„œ, /Resources/kci/JKCI.2016.28.2.213/images/PICBB48.gif๋Š” ์‹คํ—˜์ฒด์— ํ˜ผ์ž…๋œ ๊ฐ•์„ฌ์œ ์˜ ์ „์ฒด ๋ถ€ํ”ผ๋น„๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค.

3.2 ์‹คํ—˜๋ฐฉ๋ฒ•

UHPC์˜ ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ฅธ ์••์ถ•๊ฑฐ๋™์„ ์‚ดํŽด๋ณด๊ธฐ ์œ„ํ•ด, ์‹คํ—˜์ฒด๋Š” ์ง€๋ฆ„ 100mm, ๋†’์ด 200mm์˜ ํฌ๊ธฐ์˜ ์›์ฃผํ˜• ๊ณต์‹œ์ฒด๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ๊ฐ ๋ฐฐํ•ฉ๋‹น 5๊ฐœ์”ฉ ์ œ์ž‘ํ•˜์˜€๋‹ค. ์‹คํ—˜์€ ASTM C39์— ๋”ฐ๋ผ ์ˆ˜ํ–‰๋˜์—ˆ์œผ๋ฉฐ, ์‹คํ—˜์ฒด๋Š” 2,000kN ์šฉ๋Ÿ‰์˜ ๋งŒ๋Šฅ์‹œํ—˜๊ธฐ(UTM)๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ๋ณ€์œ„์ œ์–ด ๋ฐฉ๋ฒ•์œผ๋กœ 0.3mm/min ์†๋„๋กœ ์ตœ์ข…ํŒŒ๊ดด ์‹œ๊นŒ์ง€ ๊ฐ€๋ ฅํ•˜์˜€๋‹ค. ์‹คํ—˜์ฒด์˜ ๋ณ€ํ˜•์€ ์‹คํ—˜์ฒด ์ค‘์•™๋ถ€์— ์ˆ˜์ง, ์ˆ˜ํ‰๋ฐฉํ–ฅ์œผ๋กœ ๋ถ€์ฐฉ๋œ ์ŠคํŠธ๋ ˆ์ธ ๊ฒŒ์ด์ง€์— ์˜ํ•ด ์ธก์ •๋˜์—ˆ๋‹ค.

์‹คํ—˜์ฒด๋Š” UHPC ํƒ€์„ค ํ›„ 90ยฐC ์ด์ƒ์˜ ๊ณ ์˜จ์—์„œ 48์‹œ๊ฐ„ ์ฆ๊ธฐ์–‘์ƒ ํ›„ ์‹คํ—˜ ์‹œ๊นŒ์ง€ 60์ผ ๋™์•ˆ ์ƒ์˜จ์—์„œ ๊ธฐ๊ฑด ์–‘์ƒํ•˜์˜€๋‹ค.

4. ์‹คํ—˜ ๊ฒฐ๊ณผ

4.1 ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„

/Resources/kci/JKCI.2016.28.2.213/images/Figure_CONCRETE_28_2_10_F2.jpg

Fig. 2 Compressive stress-strain relationship

Fig. 2๋Š” ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ฅธ UHPC์˜ ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ๋Œ€๋ถ€๋ถ„์˜ ์‹คํ—˜์ฒด๋Š” ํŒŒ๊ดด๋ชจ๋“œ์— ๋”ฐ๋ผ ์••์ถ•์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ณก์„ ์˜ ํ˜•ํƒœ๊ฐ€ ์ƒ์ดํ•œ ๋ถ€๋ถ„๋„ ์žˆ์ง€๋งŒ ์ตœ๋Œ€๊ฐ•๋„์— ๋„๋‹ฌํ•˜๊ธฐ๊นŒ์ง€ ์„ ํ˜•๊ฑฐ๋™์„ ํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ์œผ๋ฉฐ, ์ตœ๋Œ€๊ฐ•๋„์— ๋„๋‹ฌ ์งํ›„ ๋งค์šฐ ์ทจ์„ฑ์ ์ธ ํŒŒ๊ดดํ˜•ํƒœ๋ฅผ ๋ณด์—ฌ์ฃผ์—ˆ๋‹ค. ์ด ๋•Œ๋ฌธ์— ์ด ์—ฐ๊ตฌ์—์„œ ์‚ฌ์šฉ๋œ ์‹คํ—˜๋ฐฉ๋ฒ•์œผ๋กœ๋Š” ์ตœ๋Œ€๊ฐ•๋„ ๋„๋‹ฌ ์ดํ›„์˜ ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„๋ฅผ ์–ป์„ ์ˆ˜ ์—†์—ˆ๋‹ค. ๊ธฐ์กด ์—ฐ๊ตฌ์— ๋”ฐ๋ฅด๋ฉด, ํ‰๊ท  ์••์ถ•๊ฐ•๋„๊ฐ€ 200MPa ์ด์ƒ์ธ UHPC ์—ญ์‹œ ๋งค์šฐ ์œ ์‚ฌํ•œ ๊ฑฐ๋™์„ ๋ณด์—ฌ์ฃผ์—ˆ์œผ๋ฉฐ, ์ด๋Š” ์ผ์ถ• ์••์ถ•ํ•˜์—์„œ์˜ ๋งค์šฐ ๋†’์€ ํŒŒ๊ดด์—๋„ˆ์ง€ ๋•Œ๋ฌธ์ธ ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.2) ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋œ UHPC์˜ ์••์ถ•์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ณก์„ ์€ ๋Œ€๋ถ€๋ถ„ ์ง์„ ํ˜•ํƒœ๋ฅผ ๋‚˜ํƒ€๋ƒˆ์ง€๋งŒ, ์ผ๋ถ€ ์‹คํ—˜์ฒด์˜ ๊ฒฝ์šฐ ์ง์„ ํ˜•ํƒœ๊ฐ€ ์•„๋‹Œ ๊ณก์„ ํ˜•ํƒœ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด๋Š” ์ŠคํŠธ๋ ˆ์ธ ๊ฒŒ์ด์ง€๋ฅผ ์‚ฌ์šฉํ•ด์„œ ์ธก์ •๋œ ์••์ถ• ๋ณ€ํ˜•๋ฅ ์˜ ์˜ค์ฐจ ๋•Œ๋ฌธ์ธ ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค. ์‹คํ—˜์—์„œ ๊ตฌํ•œ ์‹คํ—˜๊ฒฐ๊ณผ๋Š” Table 3์— ์š”์•ฝ๋˜์–ด ์žˆ๋‹ค.

Table 3 Summary of test results

Name

/Resources/kci/JKCI.2016.28.2.213/images/PICBD72.gif 

(%)

RI

/Resources/kci/JKCI.2016.28.2.213/images/PICBD83.gif 

(MPa)

/Resources/kci/JKCI.2016.28.2.213/images/PICBD93.gif

(MPa)

/Resources/kci/JKCI.2016.28.2.213/images/PICBDC3.gif

(mm/mm)

/Resources/kci/JKCI.2016.28.2.213/images/PICBDC4.gif

(mm/mm)

/Resources/kci/JKCI.2016.28.2.213/images/PICBDD5.gif

(mm/mm)

/Resources/kci/JKCI.2016.28.2.213/images/PICBDD6.gif

(GPa)

/Resources/kci/JKCI.2016.28.2.213/images/PICBDE6.gif

(GPa)

/Resources/kci/JKCI.2016.28.2.213/images/PICBE07.gif

/Resources/kci/JKCI.2016.28.2.213/images/PICBE27.gif

(Mean)

/Resources/kci/JKCI.2016.28.2.213/images/PICBE47.gif

/Resources/kci/JKCI.2016.28.2.213/images/PICBE87.gif

(Mean)

C0-1

0

0

151.3 

139.3

0.0035 

0.0033

0.0006 

43.0 

42.2

1.02

1.00

1.02

1.00

C0-2

134.5 

0.0033 

40.9 

0.97

0.97

C0-4

140.2 

0.0036 

-

38.8 

0.92

0.92

C0-5

131.2 

0.0029 

0.0004 

46.0 

1.09

1.09

C0.5-1

0.5

0.45

149.0 

148.2

0.0028 

0.0032

0.0009 

52.8 

46.4

1.02

1.06

1.25

1.10

C0.5-2

157.0

0.0036 

0.0006 

43.7 

1.08

1.03

C0.5-3

135.5

0.0035 

0.0004 

39.2 

0.93

0.93

C0.5-4

149.2

0.0032 

0.0006 

46.2 

1.02

1.09

C0.5-5

150.5

0.0030 

0.0007 

50.0 

1.03

1.18

C1-1

1.0

0.9

156.7

146.1

0.0035 

0.0033

0.0007

45.1 

44.4

1.07

1.05

1.07

1.05

C1-2

143.4

0.0032 

0.0010

44.2 

0.98

1.05

C1-3

154.3

0.0031 

0.0012

49.2 

1.06

1.16

C1-4

142.9

0.0034 

0.0006

42.6 

0.98

1.01

C1-5

133.4

0.0032 

0.0005

41.1 

0.91

0.97

C1.5-3

1.5

1.35

171.0

165.9

0.0043 

0.0038

0.0007

39.9 

43.7

1.17

1.08

0.94

1.04

C1.5-4

175.0

0.0037 

0.0018

46.8 

1.20

1.11

C1.5-5

151.6

0.0034 

0.0006

44.4 

1.04

1.05

C2-1

2.0

1.8

177.3

170.6

0.0033 

0.0032

0.0015

53.3 

53.9

1.22

1.17

1.26

1.28

C2-3

181.3

0.0032 

0.0009

56.7 

1.24

1.34

C2-4

162.8

0.0029 

0.0007

55.6 

1.12

1.31

C2-5

160.8

0.0032 

0.0007

50.0 

1.10

1.18

Notes: /Resources/kci/JKCI.2016.28.2.213/images/PICBF14.gif is the fiber volume ratio; RI is the reinforcement index (=/Resources/kci/JKCI.2016.28.2.213/images/PICC07D.gif); /Resources/kci/JKCI.2016.28.2.213/images/PICC08D.gif and /Resources/kci/JKCI.2016.28.2.213/images/PICC0CD.gif are length and diameter of steel fiber; /Resources/kci/JKCI.2016.28.2.213/images/PICC0ED.gif and /Resources/kci/JKCI.2016.28.2.213/images/PICC12D.gif are measured maximum stress and average maximum stress; /Resources/kci/JKCI.2016.28.2.213/images/PICC14D.gif and /Resources/kci/JKCI.2016.28.2.213/images/PICC17D.gif are measured axial and transverse strain; /Resources/kci/JKCI.2016.28.2.213/images/PICC17E.gif is the average axial strain; /Resources/kci/JKCI.2016.28.2.213/images/PICC1AE.gif is the modulus of elasticity; /Resources/kci/JKCI.2016.28.2.213/images/PICC1CE.gif is the average modulus of elasticity; /Resources/kci/JKCI.2016.28.2.213/images/PICC1EE.gif and /Resources/kci/JKCI.2016.28.2.213/images/PICC21E.gif are the maximum compressive strength and the secant modulus of elasticity of the test specimens without steel fibers, respectively. Test results of C0-3, C1.5-1, C1.5-2, and C2-2 specimens were not included because of test error.

Fig. 3(a)๋Š” ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ฅธ ์ตœ๋Œ€์••์ถ•๊ฐ•๋„(/Resources/kci/JKCI.2016.28.2.213/images/PICBB68.gif)์™€ ํ‰๊ท ๊ฐ’์„ ๋ณด์—ฌ์ค€๋‹ค. UHPC์˜ ํ‰๊ท  ์ตœ๋Œ€์••์ถ•๊ฐ•๋„๋Š” ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ๋‹ค์†Œ ์ฆ๊ฐ€ํ•˜์˜€์œผ๋ฉฐ, ํŠนํžˆ ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด 1.5%๋ถ€ํ„ฐ ๊ฐ•๋„์˜ ์ฆ๊ฐ€๊ฐ€ ๋šœ๋ ท์ด ๋‚˜ํƒ€๋‚ฌ๋‹ค. Fig. 3(b)๋Š” ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋˜์ง€ ์•Š์€ ์‹คํ—˜์ฒด์˜ ์ตœ๋Œ€์••์ถ•๊ฐ•๋„(/Resources/kci/JKCI.2016.28.2.213/images/PICBB79.gif)์— ๋Œ€ํ•œ ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋œ ์‹คํ—˜์ฒด์˜ ์ตœ๋Œ€์••์ถ•๊ฐ•๋„(/Resources/kci/JKCI.2016.28.2.213/images/PICBB7A.gif) ๋น„๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด 1%์ผ ๋•Œ๊นŒ์ง€๋Š” ๊ฐ•๋„ ๋น„๊ฐ€ ๊ฑฐ์˜ ์ผ์ •ํ•˜์˜€์œผ๋‚˜ 1.5%๋ถ€ํ„ฐ ์ตœ๋Œ€๊ฐ•๋„ ๋น„๋Š” ์ฆ๊ฐ€ํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด 1%์ผ ๋•Œ์˜ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„๋Š” ๋ฌด๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์— ๋น„ํ•ด ํ‰๊ท  ์•ฝ 7% ๊ทธ๋ฆฌ๊ณ  2%์ผ ๋•Œ๋Š” ์•ฝ 14% ์ •๋„ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ๊ฐ ์‹คํ—˜์ฒด๋ณ„ ๊ฐ•๋„ ๋น„๋Š” ์ตœ์†Œ 0.92, ์ตœ๋Œ€ 1.27๋กœ ๋‚˜ํƒ€๋‚ฌ์œผ๋ฉฐ, ๋ชจ๋“  ์‹คํ—˜์ฒด์— ๋Œ€ํ•œ ๊ฐ•๋„ ๋น„๋Š” ํ‰๊ท  1.07๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด๋Ÿฌํ•œ ์‹คํ—˜๊ฒฐ๊ณผ๋Š” ์ตœ๋Œ€์••์ถ•๊ฐ•๋„๊ฐ€ 200MPa ์ด์ƒ์ธ UHPC๋ฅผ ๋Œ€์ƒ์œผ๋กœ ์ˆ˜ํ–‰๋œ ์—ฐ๊ตฌ๊ฒฐ๊ณผ์™€ ๋น„์Šทํ•œ ๊ฒฐ๊ณผ๋ฅผ ๋ณด์˜€๋‹ค. Kang et al.2)์˜ ์—ฐ๊ตฌ์— ๋”ฐ๋ฅด๋ฉด, ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด 1%์ธ UHPC์˜ ์ตœ๋Œ€์••์ถ•๊ฐ•๋„๋Š” ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋˜์ง€ ์•Š์€ ์‹คํ—˜์ฒด์™€ ๊ฑฐ์˜ ์ผ์น˜ํ•˜๋Š” ๊ฒฝํ–ฅ์„ ๋ณด์—ฌ์ฃผ์—ˆ์œผ๋ฉฐ, ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด 2%์ธ UHPC์˜ ๊ฐ•๋„๋Š” ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋˜์ง€ ์•Š์€ ์‹คํ—˜์ฒด์— ๋น„ํ•ด ์•ฝ 6%์˜ ๊ฐ•๋„ ์ฆ๊ฐ€ ํšจ๊ณผ๊ฐ€ ์žˆ์—ˆ๋‹ค. UHPC์˜ ์ตœ๋Œ€์••์ถ•๊ฐ•๋„๋Š” ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ผ ์ฆ๊ฐ€ํ•˜๋Š” ๊ฒฝํ–ฅ์„ ๋ณด์ด๋‚˜ ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด 1%์ผ ๋•Œ๊นŒ์ง€๋Š” ๊ฐ•์„ฌ์œ ์˜ ํšจ๊ณผ๊ฐ€ ๊ฑฐ์˜ ๋‚˜ํƒ€๋‚˜์ง€ ์•Š์œผ๋ฉฐ, 1.5%์ด์ƒ ํ˜ผ์ž…๋˜์—ˆ์„ ๊ฒฝ์šฐ, ๊ฐ•๋„ ์ฆ์ง„ ํšจ๊ณผ๊ฐ€ ์žˆ๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

Fig. 4๋Š” ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ฅธ ์ตœ๋Œ€๊ฐ•๋„์ผ ๋•Œ์˜ ์ถ•๋ฐฉํ–ฅ ๋ณ€ํ˜•๋ฅ (/Resources/kci/JKCI.2016.28.2.213/images/PICBB9A.gif)์„ ๋ณด์—ฌ์ค€๋‹ค. ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ์ตœ๋Œ€์••์ถ•๊ฐ•๋„์ผ ๋•Œ ์ตœ์ข…ํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜์˜€์œผ๋ฏ€๋กœ ์ตœ๋Œ€๊ฐ•๋„์ผ ๋•Œ์˜ ๋ณ€ํ˜•๋ฅ ์€ ๊ทนํ•œ๋ณ€ํ˜•๋ฅ ๊ณผ ๊ฐ™๋‹ค๊ณ  ๊ฐ€์ •ํ•˜์˜€๋‹ค. ์ตœ์†Œ ๋ณ€ํ˜•๋ฅ ์€ 0.0028 (C0.5-1)์ด์—ˆ์œผ๋ฉฐ, ์ตœ๋Œ€ ๋ณ€ํ˜•๋ฅ ์€ 0.0043(C1.5-3), ๊ทธ๋ฆฌ๊ณ  ํ‰๊ท  ๋ณ€ํ˜•๋ฅ ์€ 0.0032~0.0035๋กœ์„œ ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ฅธ ์ถ•๋ฐฉํ–ฅ ๋ณ€ํ˜•๋ฅ ์€ ๊ฑฐ์˜ ์ผ์ •ํ•œ ๊ฐ’์„ ๋ณด์—ฌ์ฃผ์—ˆ๋‹ค. ์ŠคํŠธ๋ ˆ์ธ ๊ฒŒ์ด์ง€๋ฅผ ์‚ฌ์šฉํ•ด์„œ ๊ตฌํ•œ UHPC์˜ ์••์ถ• ๋ณ€ํ˜•๋ฅ ์€ Table 1์—์„œ ๋‚˜ํƒ€๋‚ธ ๋ฐ”์™€ ๊ฐ™์ด AFGC-SETRA4)์™€ K-UHPC5)์—์„œ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š” ๋ณ€ํ˜•๋ฅ  ๋ฒ”์œ„์— ์กด์žฌํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์—ฌ๊ธฐ์„œ, AFGC-SETRA4)์™€ K-UHPC5)์—์„œ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š” ๊ทนํ•œ๋ณ€ํ˜•๋ฅ ์€ ๊ฐ๊ฐ 0.0027๊ณผ 0.004์ด๋‹ค.

Table 1 Design recommendations for UHPC in compression

Current Codes

/Resources/kci/JKCI.2016.28.2.213/images/PICBC60.gif

/Resources/kci/JKCI.2016.28.2.213/images/PICBC81.gif

/Resources/kci/JKCI.2016.28.2.213/images/PICBCA1.gif

/Resources/kci/JKCI.2016.28.2.213/images/PICBCB2.gif

AFGC-SETRA4)

/Resources/kci/JKCI.2016.28.2.213/images/PICBD01.gif

/Resources/kci/JKCI.2016.28.2.213/images/PICBD21.gif

0.0027

50GPa

K-UHPC5)

/Resources/kci/JKCI.2016.28.2.213/images/PICBD32.gif

/Resources/kci/JKCI.2016.28.2.213/images/PICBD61.gif

0.004

45GPa

/Resources/kci/JKCI.2016.28.2.213/images/Figure_CONCRETE_28_2_10_F3.jpg

Fig. 3 Effect of fiber volume ratio on compressive strength

/Resources/kci/JKCI.2016.28.2.213/images/Figure_CONCRETE_28_2_10_F4.jpg

Fig. 4 Axial strain corresponding to maximum stress

4.2 ํŒŒ๊ดด๋ชจ๋“œ

Fig. 5๋Š” ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด 2%์ผ ๋•Œ UHPC์˜ ์ „ํ˜•์ ์ธ ํŒŒ๊ดด๋ชจ๋“œ๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋˜์ง€ ์•Š์€ ์‹คํ—˜์ฒด์˜ ๊ฒฝ์šฐ, ์ตœ๋Œ€ ๊ฐ•๋„ ๋„๋‹ฌ ์งํ›„ ํฐ ํญ๋ฐœ์Œ๊ณผ ํ•จ๊ป˜ ๋งค์šฐ ์ทจ์„ฑ์ ์ธ ํŒŒ๊ดด๊ฐ€ ๋ฐœ์ƒํ•˜์˜€๋‹ค. ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ๋Š” ๋Œ€๋ถ€๋ถ„ ๊ธธ์ด๋ฐฉํ–ฅ ๊ท ์—ด๋ฟ๋งŒ ์•„๋‹ˆ๋ผ ์‹คํ—˜์ฒด ์ค‘์‹ฌ๋ถ€์—์„œ ๊ฐ€๋กœ๋ฐฉํ–ฅ์˜ ๊ท ์—ด๋„ ๋™์‹œ์— ๋ฐœ์ƒํ•˜์˜€์œผ๋ฉฐ, ๋Œ€์ฒด์ ์œผ๋กœ ๋ถ€์žฌ ๊ธธ์ด๋ฐฉํ–ฅ์œผ๋กœ ๋ฐœ์ƒํ•œ ๊ท ์—ด๋กœ ์ตœ์ข…ํŒŒ๊ดด๋˜์—ˆ๋‹ค. ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ฅธ ์••์ถ•๊ฐ•๋„์˜ ์ฆ๊ฐ€๋Š” ๊ท ์—ด ๋ฉด์—์„œ์˜ ๊ฐ€๊ต์ž‘์šฉ์œผ๋กœ ์ธํ•ด ๊ตฌ์†ํšจ๊ณผ๊ฐ€ ๋ฐœ์ƒํ•˜์—ฌ ์ƒ๊ธด ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋˜๋‚˜, ๊ธฐ์กด ์—ฐ๊ตฌ์ž๋“ค์˜ ์—ฐ๊ตฌ๊ฒฐ๊ณผ์—์„œ ๋ณด๊ณ ๋œ ๋ฐ”์— ์˜ํ•˜๋ฉด ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ฅธ ์••์ถ•๊ฐ•๋„์˜ ์ฆ๊ฐ€๊ฐ€ ๋ชจ๋“  ์—ฐ๊ตฌ๊ฒฐ๊ณผ์—์„œ ๋šœ๋ ท์ด ๋‚˜ํƒ€๋‚˜์ง€ ์•Š๋Š” ๋ฐ”, ์ด ๋ถ€๋ถ„์— ๋Œ€ํ•œ ์ถ”๊ฐ€์ ์ธ ์—ฐ๊ตฌ๊ฐ€ ํ•„์š”ํ•  ๊ฒƒ์œผ๋กœ ์‚ฌ๋ฃŒ๋œ๋‹ค.

/Resources/kci/JKCI.2016.28.2.213/images/Figure_CONCRETE_28_2_10_F5.jpg

Fig. 5 Typical failure mode of UHPC (/Resources/kci/JKCI.2016.28.2.213/images/PICBBAB.gif=2%)

4.3 ์ฒด์ ๋ณ€ํ˜•

์••์ถ•๋ ฅ์ด ์žฌํ•˜๋˜๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๊ฒฝ์šฐ, ์••์ถ•์‘๋ ฅ์€ ๋ณ€ํ˜•๋ฅ ์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ์ตœ๋Œ€์••์ถ•๊ฐ•๋„์˜ ์•ฝ 75~90% ์ˆ˜์ค€๊นŒ์ง€ ์„ ํ˜•์œผ๋กœ ์ฆ๊ฐ€ํ•œ๋‹ค. ์„ ํ˜•๊ฑฐ๋™์„ ํ•˜์—ฌ ํŠน์ •์ง€์ ์— ๋„๋‹ฌํ•œ ์ดํ›„ ๋ถ€์žฌ์˜ ์ฒด์ ๋ณ€ํ™”๋กœ ์ธํ•ด ๋ณ€ํ˜•๋ฅ ์€ ์ ์ฐจ ๊ฐ์†Œํ•˜๊ฒŒ ๋œ๋‹ค. ์ด ๋•Œ ์••์ถ•๊ฐ•๋„๋Š” ์„œ์„œํžˆ ์ฆ๊ฐ€ํ•˜์—ฌ ์ตœ๋Œ€์••์ถ•๊ฐ•๋„์— ๋„๋‹ฌํ•˜๊ฒŒ ๋œ๋‹ค. ์ด ๋•Œ ์ฒด์ ๋ณ€ํ˜•๋ฅ ์ด ์ฆ๊ฐ€ํ•˜๋‹ค ๋‹ค์‹œ ๊ฐ์†Œํ•  ๋•Œ์˜ ์‘๋ ฅ์„ ์ž„๊ณ„๊ฐ•๋„(critical stress, /Resources/kci/JKCI.2016.28.2.213/images/PICBBBB.gif)๋ผ ํ•˜๋ฉฐ, ์ด์— ๋Œ€ํ•œ ์ •์˜๋Š” Fig. 6(a)์— ๋‚˜ํƒ€๋‚˜์žˆ๋‹ค. ์—ฌ๊ธฐ์„œ, ์ฒด์ ๋ณ€ํ˜•๋ฅ 

(/Resources/kci/JKCI.2016.28.2.213/images/PICBBDB.gif)์€ /Resources/kci/JKCI.2016.28.2.213/images/PICBC2B.gif๋กœ ๊ณ„์‚ฐ๋˜๋ฉฐ, ๊ธธ์ด

๋ฐฉํ–ฅ๊ณผ ๊ฐ€๋กœ๋ฐฉํ–ฅ์œผ๋กœ ๋ถ€์ฐฉ๋œ ์ŠคํŠธ๋ ˆ์ธ๊ฒŒ์ด์ง€ ๊ฐ’์„ ์‚ฌ์šฉํ•ด ๊ตฌํ•˜์˜€๋‹ค.

/Resources/kci/JKCI.2016.28.2.213/images/Figure_CONCRETE_28_2_10_F6.jpg

Fig. 6 Volumetric deformation

Fig. 6(b)๋Š” ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ฅธ ์ตœ๋Œ€์••์ถ•๊ฐ•๋„์— ๋Œ€ํ•œ ์ž„๊ณ„๊ฐ•๋„์˜ ๋น„(/Resources/kci/JKCI.2016.28.2.213/images/PICBC5A.gif)๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ์ธก์ •๊ฒฐ๊ณผ, ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ์ตœ๋Œ€์••์ถ•๊ฐ•๋„์— ๋Œ€ํ•œ ์ž„๊ณ„์‘๋ ฅ์˜ ๋น„๋Š” ๊ฐ์†Œํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋˜์ง€ ์•Š์€ ๊ฒฝ์šฐ ์ž„๊ณ„๊ฐ•๋„๋Š” ์ตœ๋Œ€๊ฐ•๋„์˜ 95% ์ˆ˜์ค€์ด์—ˆ์œผ๋ฉฐ, 2%์˜ ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋œ ๊ฒฝ์šฐ, ์ž„๊ณ„๊ฐ•๋„๋Š” ์ตœ๋Œ€๊ฐ•๋„์˜ 81% ์ˆ˜์ค€์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ์ตœ๋Œ€์••์ถ•๊ฐ•๋„์— ๋Œ€ํ•œ ์ž„๊ณ„์‘๋ ฅ์˜ ๋น„๊ฐ€ ๊ฐ์†Œํ•˜๋Š” ์ด์œ ๋Š” UHPC์˜ ์ดˆ๊ธฐ ๊ท ์—ด์ด ๋ฐœ์ƒํ•œ ์ดํ›„ ๊ฐ•์„ฌ์œ ์˜ ๊ฐ€๊ตํšจ๊ณผ๋กœ ์ธํ•ด ์••์ถ•๊ฐ•๋„๊ฐ€ ๋‹ค์†Œ ์ฆ๊ฐ€ํ•˜์˜€๊ธฐ ๋•Œ๋ฌธ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

4.4 ํƒ„์„ฑ๊ณ„์ˆ˜

UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ํ˜„ํ–‰ ์„ค๊ณ„๊ธฐ์ค€์— ๋”ฐ๋ผ Fig. 2์—์„œ ์ œ์‹œ๋œ ๋ฐ”์™€ ๊ฐ™์ด ์‘๋ ฅ-๋ณ€ํ˜•๋ฅ  ๊ด€๊ณ„์˜ ์›์ ์—์„œ๋ถ€ํ„ฐ ์ตœ๋Œ€๊ฐ•๋„๋ฅผ ์—ฐ๊ฒฐํ•˜๋Š” ์ง์„ ์˜ ๊ธฐ์šธ๊ธฐ๋กœ ๊ตฌํ•˜์˜€๋‹ค. Fig. 7(a)๋Š” ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ฅธ UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋œ UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ๋ฌด๋ณด๊ฐ• UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜์— ๋น„ํ•ด ํฐ ๊ฐ’์„ ๋‚˜ํƒ€๋ƒˆ์œผ๋ฉฐ, ํŠนํžˆ, ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด 1.5%์—์„œ 2%๋กœ ์ฆ๊ฐ€ํ•  ๋•Œ ํƒ„์„ฑ๊ณ„์ˆ˜์˜ ์ฆ๊ฐ€๊ฐ€ ๋šœ๋ ท์ด ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด๋Ÿฌํ•œ ๊ฒฐ๊ณผ๋Š” UHPC์˜ ์••์ถ• ๋ณ€ํ˜•๋ฅ ์€ ๊ฑฐ์˜ ์œ ์‚ฌํ•˜๊ฒŒ ๋‚˜ํƒ€๋‚œ ๋ฐ˜๋ฉด, ์ตœ๋Œ€๊ฐ•๋„๊ฐ€ ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ผ ์ฆ๊ฐ€ํ•˜์˜€๊ธฐ ๋•Œ๋ฌธ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค. ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋˜์ง€ ์•Š์€ ์‹คํ—˜์ฒด์˜ ํƒ„์„ฑ๊ณ„์ˆ˜(/Resources/kci/JKCI.2016.28.2.213/images/PICBC8A.gif)์˜ ํ‰๊ท ๊ฐ’์€ 42.3 GPa์ด์—ˆ์œผ๋ฉฐ ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋œ UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ํ‰๊ท  43.7~53GPa๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

Fig. 7(b)๋Š” ๊ฐ•์„ฌ์œ ๊ฐ€ ๋ณด๊ฐ•๋˜์ง€ ์•Š์€ UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜(/Resources/kci/JKCI.2016.28.2.213/images/PICBC9B.gif)์— ๋Œ€ํ•œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜(Ecf)์˜ ๋น„๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ์—ฌ๊ธฐ์„œ, /Resources/kci/JKCI.2016.28.2.213/images/PICBCAC.gif๋Š” ๊ฐ•์„ฌ์œ ๊ฐ€ ๋ณด๊ฐ•๋˜์ง€ ์•Š์€ 5๊ฐœ์˜ ์‹คํ—˜์ฒด์—์„œ ๊ตฌํ•œ ํƒ„์„ฑ๊ณ„์ˆ˜์˜ ํ‰๊ท ๊ฐ’์œผ๋กœ ์ •์˜ํ•˜์˜€๋‹ค. ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋˜์ง€ ์•Š์€ ๋ฌด๋ณด๊ฐ• UHPC์˜ ํ‰๊ท  ํƒ„์„ฑ๊ณ„์ˆ˜์— ๋Œ€ํ•œ ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋œ UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜์˜ ๋น„๋Š” ์ตœ์†Œ 0.92์—์„œ ์ตœ๋Œ€ 1.35๋กœ ๋‚˜ํƒ€๋‚ฌ์œผ๋ฉฐ, ๋ชจ๋“  ์‹คํ—˜๊ฒฐ๊ณผ์— ๋Œ€ํ•œ ํƒ„์„ฑ๊ณ„์ˆ˜ ๋น„์˜ ํ‰๊ท ๊ฐ’์€ 1.10์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

์ „์ˆ ํ•œ ๋ฐ”์™€ ๊ฐ™์ด ํ˜„ํ–‰ ์„ค๊ณ„๊ธฐ์ค€์—์„œ๋Š” ๋ชจ๋‘ ํŠน์ •๊ฐ•๋„์˜ UHPC์— ๋Œ€ํ•œ ํƒ„์„ฑ๊ณ„์ˆ˜๋ฅผ ์ œ์•ˆํ•˜๊ณ  ์žˆ๋‹ค. AFGC-SETRA4)์—์„œ๋Š” ์••์ถ•๊ฐ•๋„ ํŠน์„ฑ์น˜๊ฐ€ 180MPa์ธ UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋ฅผ 50GPa๋กœ ์ œ์•ˆํ•˜๊ณ  ์žˆ์œผ๋ฉฐ, K-UHPC5)์—์„œ๋Š” 1.5%์˜ ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋œ UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋ฅผ 45GPa๋กœ ์ œ์‹œํ•˜๊ณ  ์žˆ๋‹ค. Fig. 7(a)์—์„œ ๋ณด์ด๋Š” ๋ฐ”์™€ ๊ฐ™์ด ํ˜„ํ–‰ ๊ธฐ์ค€์—์„œ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š” ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ์‹คํ—˜๊ฐ’์— ๋น„ํ•ด ๋‹ค์†Œ ๊ณผ๋Œ€ํ‰๊ฐ€๋˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ํ•˜์ง€๋งŒ ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด 2%์ผ ๊ฒฝ์šฐ, ์‹คํ—˜์—์„œ ๊ตฌํ•œ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ๊ธฐ์ค€์—์„œ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š” ํƒ„์„ฑ๊ณ„์ˆ˜ ๊ฐ’์„ ์ดˆ๊ณผํ•˜์˜€๋‹ค. ๋”ฐ๋ผ์„œ ํ˜„ํ–‰ ๊ธฐ์ค€์—์„œ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š” ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ์ˆ˜์ •๋  ํ•„์š”๊ฐ€ ์žˆ๋‹ค.

/Resources/kci/JKCI.2016.28.2.213/images/Figure_CONCRETE_28_2_10_F7.jpg

Fig. 7 Effect of fiber volume ratio on the modulus of elasticity

5. ๊ฒฐ๊ณผ ๋ถ„์„

5.1 ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„

Table 4๋Š” ๊ธฐ์กด์—ฐ๊ตฌ์—์„œ ์ œ์‹œ๋œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„ ์ œ์•ˆ์‹์„ ๋ณด์—ฌ์ค€๋‹ค. ๊ธฐ์กด ๋ชจ๋ธ์—์„œ ์ œ์‹œ๋œ ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋œ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„๋Š” ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋˜์ง€ ์•Š์€ ๋ฌด๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„์— ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ  ๋˜๋Š” ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜(RI)๋ฅผ ๋”ํ•œ ๊ฐ’์œผ๋กœ ์ œ์•ˆ๋˜์—ˆ๋‹ค. ์ œ์•ˆ๋œ ์••์ถ•๊ฐ•๋„ ๋ชจ๋ธ์˜ ๋น„๊ต๋ฅผ ์œ„ํ•ด Table 4์— ๋‚˜ํƒ€๋‚ธ ๋ฐ”์™€ ๊ฐ™์ด Fanella et al.,6) Ezeldin et al.,7) Nataraja et al.,8) Song et al.,9) Yazici et al.,10) Kang et al.1,2) ๋“ฑ ๊ธฐ์กด ์—ฐ๊ตฌ์ž๋“ค์— ์˜ํ•ด ์ œ์•ˆ๋œ ์••์ถ•๊ฐ•๋„ ์‹์„ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ๋ถ„์„์„ ์œ„ํ•ด ์‚ฌ์šฉ๋œ ์‹คํ—˜์ฒด๋Š” ์ด 146๊ฐœ์ด๋ฉฐ, ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ (/Resources/kci/JKCI.2016.28.2.213/images/PICBCAD.gif)์€ 0~5%, ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜(RI)๋Š” 0~3.25, ์••์ถ•๊ฐ•๋„(/Resources/kci/JKCI.2016.28.2.213/images/PICBCBD.gif)๋Š” 29.4~235.1MPa, ๊ทธ๋ฆฌ๊ณ  ํƒ„์„ฑ๊ณ„์ˆ˜(/Resources/kci/JKCI.2016.28.2.213/images/PICBCCE.gif)๋Š” 27.6~56.7GPa์ด๋‹ค. ๊ธฐ์กด ์—ฐ๊ตฌ์ž๋“ค์— ์˜ํ•ด ์ˆ˜ํ–‰๋œ ์‹คํ—˜๊ฒฐ๊ณผ๋Š” Table 5์— ๋‚˜ํƒ€๋‚˜์žˆ๋‹ค.

Table 4 Existing compressive strength equations

Authors

Compressive strength equations

Fanella et al.6)

/Resources/kci/JKCI.2016.28.2.213/images/PICC25D.gif

Ezeldin et al.7)

/Resources/kci/JKCI.2016.28.2.213/images/PICC2EB.gif

Nataraja et al.8)

/Resources/kci/JKCI.2016.28.2.213/images/PICC369.gif

Song et al.9)

/Resources/kci/JKCI.2016.28.2.213/images/PICC399.gif

Yazici et al.10)

/Resources/kci/JKCI.2016.28.2.213/images/PICC446.gif

Kang et al.1,2)

/Resources/kci/JKCI.2016.28.2.213/images/PICC4B4.gif

Notes: /Resources/kci/JKCI.2016.28.2.213/images/PICC4F4.gif is the maximum compressive strength of fiber reinforced concrete; /Resources/kci/JKCI.2016.28.2.213/images/PICC504.gif is the compressive strength of concrete without steel fibers; /Resources/kci/JKCI.2016.28.2.213/images/PICC553.gif is the reinforcement index (/Resources/kci/JKCI.2016.28.2.213/images/PICC5A3.gif); /Resources/kci/JKCI.2016.28.2.213/images/PICC601.gif is the reinforcement index by weight; /Resources/kci/JKCI.2016.28.2.213/images/PICC612.gif is the fiber volume ratio; and /Resources/kci/JKCI.2016.28.2.213/images/PICC632.gif and /Resources/kci/JKCI.2016.28.2.213/images/PICC652.gif are a length and a diameter of the steel fiber, respectively.

Table 5 Test results in previous researches

Authors

No. of

specimens

/Resources/kci/JKCI.2016.28.2.213/images/PICC663.gif

(%)

RI

/Resources/kci/JKCI.2016.28.2.213/images/PICC683.gif

(MPa)

/Resources/kci/JKCI.2016.28.2.213/images/PICC6E2.gif

(GPa)

Ezeldin et al.7)

10

0~0.76

0~2.5

35.9

~47.9

30.7

~40.5

Nataraja et al.8)

14

0~1

0~2.67

29.4

~49.2

-

Song et al.9)

5

0~2

0~1.27

85

~98

-

Hsu et al.11)

19

0.5~1

0.3~0.6

62.9

~88

27.6

~29.4

Yazici et al.10)

10

0~1.5

0~1.2

49.1

~58.3

-

Kang et al.1)

(series I)

27

0~5

0~3.25

79.5

~112.9

-

Kang et al.1)

(series II)

18

0~3

0~1.95

48.3

~126.3

-

Kang et al.1)

(series III)

18

0~5

0~3.25

201.1

~235.1

-

This study

25

0~2

0~1.47

131.2

~181.3

38.8

~56.7

Total

121

0~5

0~3.25

29.4

~235.1

27.6

~56.7

Fig. 8(a)๋Š” ๊ธฐ์กด ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ์ด์šฉํ•ด ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ฅธ ๋ฌด๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ ์••์ถ•๊ฐ•๋„์— ๋Œ€ํ•œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„ ๋น„(/Resources/kci/JKCI.2016.28.2.213/images/PICBCDE.gif)๋ฅผ ๋ณด์—ฌ์ค€๋‹ค. ๊ธฐ์กด ์‹คํ—˜์ฒด์˜ ์••์ถ•๊ฐ•๋„ ๋น„๋Š” ๋ชจ๋‘ 0.96~1.48์— ์กด์žฌํ•˜์˜€๊ณ , ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ฅธ ์••์ถ•๊ฐ•๋„์˜ ์ฆ๊ฐ€๋Š” ๋šœ๋ ท์ด ๋‚˜ํƒ€๋‚˜์ง€ ์•Š์•˜๋‹ค. ๊ทธ๋ฆฌ๊ณ  ๊ธฐ์กด ์‹คํ—˜๊ฐ’ ์ค‘ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„๊ฐ€ ๋ฌด๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„์— ๋น„ํ•ด 48%์ด์ƒ ์ฆ๊ฐ€ํ•˜๋Š” ๊ฒฝ์šฐ๋Š” ๋ฐœ๊ฒฌ๋˜์ง€ ์•Š์•˜๋‹ค.

Table 4์—์„œ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š” ์••์ถ•๊ฐ•๋„ ์ œ์•ˆ์‹์˜ ๊ฒฝ์šฐ, ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„(/Resources/kci/JKCI.2016.28.2.213/images/PICBCEF.gif)๋Š” ๋ฌด๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„(/Resources/kci/JKCI.2016.28.2.213/images/PICBD00.gif)๋ณด๋‹ค ํฌ๋ฉฐ, ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜(/Resources/kci/JKCI.2016.28.2.213/images/PICBD10.gif)๊ฐ€ ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ์ฆ๊ฐ€ํ•˜๋Š” ๊ฒƒ์„ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ๋‹ค. ์ด๋Ÿฌํ•œ ์ œ์•ˆ์‹์€ ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜์— ๋Œ€ํ•œ ๋ฒ”์œ„๊ฐ€ ์ œ์‹œ๋˜์–ด ์žˆ์ง€ ์•Š๊ธฐ ๋•Œ๋ฌธ์—, ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜๊ฐ€ ์ฆ๊ฐ€ํ•˜๋ฉด ์˜ˆ์ธก๋œ ์••์ถ•๊ฐ•๋„๋Š” ๋ฐ˜๋“œ์‹œ ์ฆ๊ฐ€ํ•˜๊ฒŒ ๋œ๋‹ค. ํ•˜์ง€๋งŒ, Fig. 8(b)์—์„œ ๋ณด์ด๋Š” ๋ฐ”์™€ ๊ฐ™์ด, ์ผ๋ถ€ ์‹คํ—˜์ฒด์—์„œ ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ฅธ ์••์ถ•๊ฐ•๋„์˜ ์ฆ๊ฐ€๊ฐ€ ๋‚˜ํƒ€๋‚˜๊ธด ํ•˜์ง€๋งŒ ์‹คํ—˜์ฒด ์ „์ฒด๋กœ ๋ณด์•˜์„ ๋•Œ ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ฅธ ์••์ถ•๊ฐ•๋„์˜ ์ฆ๊ฐ€๋Š” ๋ช…ํ™•ํ•˜๊ฒŒ ๋‚˜ํƒ€๋‚˜์ง„ ์•Š๋Š”๋‹ค. ์ด๋Ÿฌํ•œ ์—ฐ๊ตฌ๊ฒฐ๊ณผ๋ฅผ ๋ฐ”ํƒ•์œผ๋กœ ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„๋ฅผ ํ‰๊ท ๊ฐ’์„ ์‚ฌ์šฉํ•˜์—ฌ ๋‹ค์Œ ์‹(1)๊ณผ ๊ฐ™์ด ์ œ์•ˆํ•œ๋‹ค.

/Resources/kci/JKCI.2016.28.2.213/images/Figure_CONCRETE_28_2_10_F8.jpg

Fig. 8 Effect of steel fiber on compressive strength

/Resources/kci/JKCI.2016.28.2.213/images/PICBD21.gif (1)

์—ฌ๊ธฐ์„œ, /Resources/kci/JKCI.2016.28.2.213/images/PICBD32.gif๋Š” ๊ฐ•์„ฌ์œ ๊ฐ€ ํ˜ผ์ž…๋˜์ง€ ์•Š์€ ๋ฌด๋ณด๊ฐ• UHPC์˜ ์••์ถ•๊ฐ•๋„์ด๋‹ค.

Fig. 9๋Š” ์‹(1)์—์„œ ์ œ์•ˆ๋œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์••์ถ•๊ฐ•๋„์™€ ๊ธฐ์กด ์‹คํ—˜๊ฐ’์„ ๋น„๊ตํ•œ ๊ฒƒ์ด๋‹ค. ์ œ์•ˆ๋œ ์••์ถ•๊ฐ•๋„์— ๋Œ€ํ•œ ์‹คํ—˜๊ฐ’์€ ํ‰๊ท  1.02, ํ‘œ์ค€ํŽธ์ฐจ 0.08๋กœ ์‹คํ—˜๊ฐ’๊ณผ ์ž˜ ์ผ์น˜ํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. Table 6์€ ์ œ์•ˆ๋œ ๊ฐ•๋„์‹๊ณผ ๊ธฐ์กด ์ œ์•ˆ์‹๊ณผ์˜ ๋น„๊ต๋ฅผ ๋‚˜ํƒ€๋‚ธ๋‹ค. ๋น„๊ต๋ฅผ ์œ„ํ•ด Table 4์˜ ์ œ์•ˆ์‹ ์ค‘ ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์„ ๋ถ€ํ”ผ๋น„๋กœ ํ‘œํ˜„ํ•œ Fanella ์‹6)๊ณผ Kang ์‹1,2)์„ ์‚ฌ์šฉํ•˜์˜€๋‹ค. Fanella et al.6)์™€ Kang et al.1,2)์— ์˜ํ•ด ์ œ์•ˆ๋œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์••์ถ•๊ฐ•๋„๋Š” ๊ฐ๊ฐ ํ‰๊ท  1.08, 0.97, ํ‘œ์ค€ํŽธ์ฐจ๋Š” 0.08, 0.09๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ๋”ฐ๋ผ์„œ ์ œ์•ˆ๋œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„๋Š” ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ๊ณผ ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜์™€๋Š” ์ƒ๊ด€์—†์ด ์••์ถ•๊ฐ•๋„๊ฐ€ 29.4~235.1MPa์ธ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์— ๋Œ€ํ•ด ์ ์šฉ๊ฐ€๋Šฅํ•  ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

Table 6 Ratio of test results to predicted compressive strength (/Resources/kci/JKCI.2016.28.2.213/images/PICC7FC.gif)

Authors

Fanellaโ€™s Eq.

Kangโ€™s Eq.

Proposed

Mean (S.D)

Mean (S.D)

Mean (S.D)

Ezeldin et al.7)

1.11 (0.08)

0.92 (0.09)

1.09 (0.09)

Nataraja et al.8)

1.04 (0.07)

0.83 (0.08)

1.03 (0.08)

Song et al.9)

1.10 (0.03)

1.04 (0.02)

1.02 (0.03)

Yazici et al.10)

1.10 (0.05)

1.02 (0.06)

1.02 (0.05)

Kang et al.1)

1.06 (0.07)

0.97 (0.04)

1.00 (0.08)

This study (Eq.(1))

1.11 (0.10)

1.07 (0.08)

1.02 (0.09)

Total

1.08 (0.08)

0.97 (0.09)

1.03 (0.08)

Note: /Resources/kci/JKCI.2016.28.2.213/images/PICC86B.gif is the maximum compressive strength obtained from the tests and /Resources/kci/JKCI.2016.28.2.213/images/PICC89B.gif is the predicted compressive strength.

/Resources/kci/JKCI.2016.28.2.213/images/Figure_CONCRETE_28_2_10_F9.jpg

Fig. 9 Comparison of predicted strength with test data

5.2 ํƒ„์„ฑ๊ณ„์ˆ˜

๊ธฐ์กด ์—ฐ๊ตฌ์— ๋”ฐ๋ฅด๋ฉด, ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ๊ฐ•์„ฌ์œ  ๋ถ€ํ”ผ๋น„ ๋˜๋Š” ์ค‘๋Ÿ‰๋น„๋กœ ๋‚˜ํƒ€๋‚ธ ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜์— ๋”ฐ๋ผ ๋‹ฌ๋ผ์ง€๋ฉฐ, ๋ฌด๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ํƒ„์„ฑ๊ณ„์ˆ˜์— ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜(RI)๋ฅผ ๋”ํ•œ ๊ฐ’์œผ๋กœ ์ œ์•ˆ๋˜์—ˆ๋‹ค. Ezeldin et al.7)๊ณผ Nataraja et al.8)์€ ์••์ถ•๊ฐ•๋„๊ฐ€ 50MPa ์ดํ•˜์ธ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋ฅผ /Resources/kci/JKCI.2016.28.2.213/images/PICBD61.gif์™€ ๊ฐ™์ด ์ œ์•ˆํ•˜์˜€์œผ๋ฉฐ, Kang et al.2)์€ ์••์ถ•๊ฐ•๋„๊ฐ€ 200MPa ์ด์ƒ์ธ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋ฅผ /Resources/kci/JKCI.2016.28.2.213/images/PICBD82.gif์™€ ๊ฐ™์ด ์ œ์•ˆํ•˜์˜€๋‹ค. ์ด๋Ÿฌํ•œ ์—ฐ๊ตฌ๊ฒฐ๊ณผ๋Š” ์„ฌ์œ ๋ณด๊ฐ•์ง€์ˆ˜์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ผ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๊ฐ€ ์ฆ๊ฐ€ํ•œ๋‹ค๋Š” ๊ฒƒ์„ ์˜๋ฏธํ•œ๋‹ค. ํ•˜์ง€๋งŒ, Fig. 10์—์„œ ๋ณผ ์ˆ˜ ์žˆ๋“ฏ์ด, ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ์••์ถ•๊ฐ•๋„(/Resources/kci/JKCI.2016.28.2.213/images/PICBD92.gif)์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ผ ์ฆ๊ฐ€ํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด๋Ÿฌํ•œ ์—ฐ๊ตฌ๊ฒฐ๊ณผ๋ฅผ ๋ฐ”ํƒ•์œผ๋กœ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋ฅผ ๋‹ค์Œ ์‹(2)์™€ ๊ฐ™์ด ์••์ถ•๊ฐ•๋„์˜ ํ•จ์ˆ˜๋กœ ์ œ์•ˆํ•œ๋‹ค.

/Resources/kci/JKCI.2016.28.2.213/images/Figure_CONCRETE_28_2_10_F10.jpg

Fig. 10 Modulus of elasticity

/Resources/kci/JKCI.2016.28.2.213/images/PICBDD2.gif (2)

์ œ์•ˆ๋œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” Fig. 10์— ๋‚˜ํƒ€๋‚˜์žˆ๋‹ค. ๊ธฐ์กด ์—ฐ๊ตฌ๊ฒฐ๊ณผ์™€์˜ ๋น„๊ต๋ฅผ ์œ„ํ•ด ์••์ถ•๊ฐ•๋„๊ฐ€ 35.9~47.9MPa, 201~235MPa์ธ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์™€ UHPC๋ฅผ ๋Œ€์ƒ์œผ๋กœ ์‹คํ—˜์—ฐ๊ตฌ๋ฅผ ์ˆ˜ํ–‰ํ•œ Ezeldin et al.7)๊ณผ Kang et al.2)์˜ ์‹คํ—˜๊ฒฐ๊ณผ๋ฅผ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ๋น„๋ก ์ด ์—ฐ๊ตฌ์—์„œ ์‚ฌ์šฉ๋œ UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜์˜ ํŽธ์ฐจ๊ฐ€ ๊ธฐ์กด ์‹คํ—˜๊ฒฐ๊ณผ์— ๋น„ํ•ด ๋‹ค์†Œ ํฌ๊ฒŒ ๋‚˜ํƒ€๋‚ฌ์ง€๋งŒ, ์ œ์•ˆ๋œ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ์‹คํ—˜๊ฒฐ๊ณผ์™€ ๋น„๊ต์  ์ž˜ ์ผ์น˜ํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. Fig. 10์—์„œ ์ด ์—ฐ๊ตฌ์—์„œ ์‚ฌ์šฉ๋œ ์‹คํ—˜์ฒด์˜ ํƒ„์„ฑ๊ณ„์ˆ˜์˜ ํŽธ์ฐจ๊ฐ€ ๋‹ค๋ฅธ ์‹คํ—˜์ฒด์— ๋น„ํ•ด ๋‹ค์†Œ ๋‚˜ํƒ€๋‚œ ๊ฒƒ์€, ์‹คํ—˜์ฒด์˜ ๊ทนํ•œ ๋ณ€ํ˜•๋ฅ ์€ ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ๊ณผ ์ƒ๊ด€์—†์ด ๊ฑฐ์˜ ์œ ์‚ฌํ•˜๊ฒŒ ๋‚˜ํƒ€๋‚œ ๋ฐ˜๋ฉด, ์ตœ๋Œ€๊ฐ•๋„๊ฐ€ ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ผ ์ฐจ์ด๊ฐ€ ๋‚ฌ๊ธฐ ๋•Œ๋ฌธ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค. Table 7์€ ๊ธฐ์กด ์—ฐ๊ตฌ์—์„œ ์ œ์•ˆ๋œ ํƒ„์„ฑ๊ณ„์ˆ˜์™€ ์‹คํ—˜๊ฐ’์„ ์ƒํ˜ธ๋น„๊ตํ•œ ๊ฒƒ์ด๋‹ค. ์ด ์—ฐ๊ตฌ์—์„œ ์ œ์•ˆ๋œ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ์‹คํ—˜๊ฐ’์— ๋Œ€ํ•ด ํ‰๊ท  1.01, ํ‘œ์ค€ํŽธ์ฐจ 0.07์„ ๋‚˜ํƒ€๋ƒˆ์œผ๋ฉฐ, ์‹คํ—˜๊ฐ’์„ ๋น„๊ต์  ์ž˜ ์˜ˆ์ธกํ•˜์˜€๋‹ค.

Table 7 Ratio of test results to predicted modulus of elasticity (/Resources/kci/JKCI.2016.28.2.213/images/PICC8CA.gif)

Authors

Ezeldinโ€™s Eq.

Kangโ€™s Eq.

Proposed

Mean (S.D)

Mean (S.D)

Mean (S.D)

Ezeldin et al.7)

0.98 (0.05)

1.06 (0.07)

1.02 (0.07)

Kang et al.2)

0.90 (0.05)

0.99 (0.02)

1.00 (0.02)

This study

1.05 (0.11)

1.09 (0.11)

1.01 (0.10)

Total

0.98 (0.10)

1.05 (0.09)

1.01 (0.07)

Note:/Resources/kci/JKCI.2016.28.2.213/images/PICC90A.gif is the modulus of elasticity obtained from the tests and/Resources/kci/JKCI.2016.28.2.213/images/PICC93A.gif is the predicted modulus of elasticity.

6. ๊ฒฐ    ๋ก 

์ด ์—ฐ๊ตฌ์—์„œ๋Š” ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ฅธ UHPC์˜ ์••์ถ•์‹คํ—˜์„ ํ†ตํ•ด ์••์ถ•๊ฑฐ๋™์„ ์‚ดํŽด๋ณด์•˜๋‹ค. ์‹คํ—˜์—ฐ๊ตฌ๋ฅผ ํ†ตํ•ด ์–ป์€ ๊ฒฐ๋ก ์€ ๋‹ค์Œ๊ณผ ๊ฐ™๋‹ค.

1)์ด ์—ฐ๊ตฌ์—์„œ ์‚ฌ์šฉ๋œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• UHPC๋Š” ์ตœ์ข…ํŒŒ๊ดด ์‹œ๊นŒ์ง€ ์„ ํ˜•๊ฑฐ๋™์„ ํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ์œผ๋ฉฐ, ์ตœ๋Œ€ ์••์ถ•๊ฐ•๋„์— ๋„๋‹ฌ ์งํ›„ ๋ฐœ์ƒํ•˜๋Š” ์ทจ์„ฑํŒŒ๊ดด๋กœ ์ธํ•ด ์ตœ๋Œ€๊ฐ•๋„ ์ดํ›„์˜ ๊ฑฐ๋™์„ ์‚ดํŽด๋ณผ ์ˆ˜๊ฐ€ ์—†์—ˆ๋‹ค. ์ด๋Ÿฌํ•œ ํ˜„์ƒ์€ ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ๊ณผ๋Š” ์ƒ๊ด€์—†์ด ๋ชจ๋“  ์‹คํ—˜์ฒด์„œ ๋ฐœ์ƒํ•˜์˜€์œผ๋ฉฐ, UHPC์˜ ๋งค์šฐ ๋†’์€ ํŒŒ๊ดด์—๋„ˆ์ง€ ๋•Œ๋ฌธ์ธ ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

2)๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก UHPC์˜ ์••์ถ•๊ฐ•๋„๋Š” ๋Œ€์ฒด๋กœ ์ฆ๊ฐ€ํ•˜๋Š” ๊ฒฝํ–ฅ์„ ๋ณด์˜€๋‹ค. ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์ด 1%์ผ ๋•Œ๊นŒ์ง€๋Š” ๊ฐ•๋„์˜ ๋ณ€ํ™”๊ฐ€ ํฌ์ง€ ์•Š์•˜์œผ๋‚˜, 1.5%๋ฅผ ์ด์ƒ์ธ ๊ฒฝ์šฐ, ์••์ถ•๊ฐ•๋„์˜ ์ฆ๊ฐ€๊ฐ€ ๋šœ๋ ท์ด ๋‚˜ํƒ€๋‚ฌ๋‹ค.

3)๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์— ๋”ฐ๋ฅธ UHPC์˜ ๊ทนํ•œ๋ณ€ํ˜•๋ฅ ์€ 0.0032~ 0.0035๋กœ์„œ ๊ฑฐ์˜ ์ผ์ •ํ•œ ๊ฐ’์„ ๋ณด์—ฌ์ฃผ์—ˆ๋‹ค. AFGC-SETRA์—์„œ ์ œ์‹œํ•˜๊ณ  ์žˆ๋Š” ๊ทนํ•œ๋ณ€ํ˜•๋ฅ ์€ ์‹คํ—˜๊ฐ’์— ๋Œ€ํ•ด ๋ณด์ˆ˜์ ์ธ ๊ฐ’์„ ์ œ์‹œํ•˜๊ณ  ์žˆ์œผ๋ฉฐ, K-UHPC์€ ๋‹ค์†Œ ๊ณผ๋Œ€ํ‰๊ฐ€ํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

4)๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…๋ฅ ์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ผ ๋‹ค์†Œ ์ฆ๊ฐ€ํ•˜๋Š” ๊ฒฝํ–ฅ์„ ๋ณด์˜€์œผ๋ฉฐ, ๊ฐ•์„ฌ์œ ์˜ ๋ณด๊ฐ•์œผ๋กœ ์ธํ•ด ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ์•ฝ 10% ์ •๋„ ์ฆ๊ฐ€ํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค.

5)๊ธฐ์กด ์‹คํ—˜ ์—ฐ๊ตฌ๊ฒฐ๊ณผ๋ฅผ ๋ฐ”ํƒ•์œผ๋กœ ๋ฌด๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„์— ๋Œ€ํ•œ ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„๋ฅผ ๋ถ„์„ํ•œ ๊ฒฐ๊ณผ, ๊ฐ•์„ฌ์œ  ํ˜ผ์ž…์œผ๋กœ ์ธํ•ด ์••์ถ•๊ฐ•๋„๋Š” ์•ฝ 10% ์ •๋„ ์ฆ๊ฐ€ํ•˜๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด๋Ÿฌํ•œ ๊ฒฐ๊ณผ๋ฅผ ๋ฐ”ํƒ•์œผ๋กœ ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„๋ฅผ ๋ฌด๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ์••์ถ•๊ฐ•๋„์˜ ํ•จ์ˆ˜๋กœ ํ‘œํ˜„ํ•˜์˜€๋‹ค.

6)๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• UHPC์˜ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ์••์ถ•๊ฐ•๋„์˜ ์˜ํ–ฅ์„ ๋ฐ›๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด ์—ฐ๊ตฌ์—์„œ๋Š” ์••์ถ•๊ฐ•๋„์˜ ํ•จ์ˆ˜๋กœ ํƒ„์„ฑ๊ณ„์ˆ˜๊ฐ€ ์ œ์•ˆ๋˜์—ˆ์œผ๋ฉฐ, ์ œ์•ˆ๋œ ํƒ„์„ฑ๊ณ„์ˆ˜๋Š” ๊ฐ•์„ฌ์œ  ๋ณด๊ฐ• ์ฝ˜ํฌ๋ฆฌํŠธ์— ์ ์šฉ๊ฐ€๋Šฅํ•  ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

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