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Journal of the Korea Concrete Institute

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




์ˆ˜์‚ฐํ™”์นผ๋ฅจ, ์‚ฐํ™”๋งˆ๊ทธ๋„ค์Š˜, ์•Œ์นผ๋ฆฌ ํ™œ์„ฑํ™” ์Šฌ๋ž˜๊ทธ ์‹œ๋ฉ˜ํŠธ, ๊ฐ•๋„, ๊ฑด์กฐ์ˆ˜์ถ•
Potassium hydroxide, Magnesium oxide, Alkali-activated slag cement, Strength, Drying shrinkage

1. ์„œ ๋ก 

์•Œ์นผ๋ฆฌ ํ™œ์„ฑํ™” ์‹œ๋ฉ˜ํŠธ (alkali-activated cement; AAC)๋Š” ๊ธฐ์กด์˜ ๋ณดํ†ต ํฌํ‹€๋žœ๋“œ ์‹œ๋ฉ˜ํŠธ (Ordinary Portland Cement; OPC)๋ฅผ ๋Œ€์ฒดํ•  ์ˆ˜ ์žˆ๋Š” ์ฐจ์„ธ๋Œ€ ์‹œ๋ฉ˜ํŠธ ์žฌ๋ฃŒ๋กœ ๊ตญ๋‚ด์™ธ์ ์œผ ๋กœ ๋งŽ์€ ์—ฐ๊ตฌ๊ฐ€ ์ด๋ฃจ์–ด์ง€๊ณ  ์žˆ๋‹ค (Pacheco-Torgal et al., 2012; Vladimir ลฝivica, 2007). ์ง€๊ธˆ๊นŒ์ง€ ๊ตญ๋‚ด์™ธ AAC์— ๋Œ€ํ•œ ์—ฐ๊ตฌ ๊ฒฐ๊ณผ๋ฅผ ํ†ตํ•ด AAC๋Š” OPC์™€ ๋น„๊ตํ•˜์—ฌ ์šฐ์ˆ˜ํ•œ ๊ฐ•๋„ ํŠน์„ฑ๊ณผ ๋‚ด๊ตฌ์„ฑ์„ ๊ฐ€์ง€๊ณ  ์žˆ์Œ์ด ๋ณด๊ณ ๋˜๊ณ  ์žˆ๋‹ค (Douglas et al., 1992). ๋˜ํ•œ ํฌ์กธ๋ž€ ์žฌ๋ฃŒ์˜ ํŠน์„ฑ์ด๋‚˜ ํ™œ์„ฑํ™”์ œ, ์–‘์ƒ๋ฐฉ๋ฒ• ๋“ฑ ์— ๋”ฐ๋ฅธ AAC์˜ ํŠน์„ฑ์— ๋Œ€ํ•œ ์—ฐ๊ตฌ ๊ฒฐ๊ณผ๋“ค์ด ๋งŽ์ด ๋ณด๊ณ ๋˜๊ณ  ์žˆ์ง€๋งŒ, ์•„์ง๊นŒ์ง€ AAC์˜ ๋ฐ˜์‘ ๋ฉ”์ปค๋‹ˆ์ฆ˜์ด ๋ช…ํ™•ํžˆ ๋ฐํ˜€์ง€์ง€ ์•Š๊ณ  ์žˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ OPC์™€ ๋น„๊ตํ•˜์—ฌ ์ƒ๋Œ€์ ์œผ๋กœ ๊ธ‰๊ฒฉํžˆ ๋น ๋ฅธ ์‘๊ฒฐ๊ณผ ๋†’์€ ๊ฑด์กฐ์ˆ˜์ถ•์€ ๊ฐœ์„ ํ•ด์•ผ ํ•  AAC์˜ ํŠน์„ฑ ์ค‘ ํ•˜๋‚˜ ๋กœ ์–ธ๊ธ‰๋˜๊ณ  ์žˆ๋‹ค. ์ด์— ๋”ฐ๋ผ AAC์˜ ๊ฑด์กฐ์ˆ˜์ถ•์„ ๊ฐ์†Œ์‹œํ‚ค ๊ธฐ ์œ„ํ•ด์„œ ๋งŽ์€ ์—ฐ๊ตฌ์ž๋“ค์ด ๋‹ค์–‘ํ•œ ๋ฐฉ๋ฒ•์„ ํ†ตํ•ด ์—ฐ๊ตฌ๊ฒฐ๊ณผ๋ฅผ ๋ฐœํ‘œํ•˜๊ณ  ์žˆ๋‹ค. AAC์˜ ๊ฑด์กฐ์ˆ˜์ถ• ์ €๊ฐ์— ๊ด€ํ•œ ์—ฐ๊ตฌ์—๋Š” ๋‹ค ์–‘ํ•œ ๋ฌด๊ธฐํ˜ผํ™”์žฌ, ์ˆ˜์ถ•์ €๊ฐ์ œ, ์–‘์ƒ์˜จ๋„ ๋“ฑ์˜ ์š”์ธ์„ ๊ณ ๋ คํ•œ ์—ฐ๊ตฌ๊ฐ€ ๋‹ค์ˆ˜ ์žˆ์—ˆ๋‹ค (Palacios and Puertas, 2007; Collins and Sanjayan, 2000; Ismail et al., 2013). ํŠนํžˆ ๊ทผ๋ž˜์— AAC ์˜ ๊ฑด์กฐ์ˆ˜์ถ• ๊ด€ํ•œ ์—ฐ๊ตฌ ์ค‘ MgO๋ฅผ ์‚ฌ์šฉํ•œ ์—ฐ๊ตฌ๊ฐ€ ๋ณด๊ณ ๋˜์—ˆ ๋‹ค (Jang et al., 2015; Fang et al., 2011; Haha et al., 2011).

์ตœ๊ทผ ์ค‘๊ตญ์—์„œ๋Š” ์ €์˜จ์†Œ์„ฑ๋œ (light-burned) MgO๋ฅผ ์‚ฌ์šฉ ํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ ๊ตฌ์กฐ๋ฌผ์˜ ํŠน์„ฑ์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๊ฒฐ๊ณผ ๋ฐœํ‘œ (Jin et al., 2015; Li et al., 2014; Jin and Al-Tabbaa, 2014; Fang et al., 2011; Gao et al., 2007; Mo and Deng, 2010)์™€ ํ•จ๊ป˜ ๊ตญ๋‚ด์—์„œ๋„ ์ €์˜จ์†Œ์„ฑ๋œ MgO๋ฅผ ์‚ฌ์šฉํ•œ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ํŠน์„ฑ์— ๊ด€ํ•œ ์—ฐ๊ตฌ๊ฐ€ ๋ช‡๋ช‡ ์—ฐ๊ตฌ์ž๋“ค์— ์˜ํ•ด ๋ฐœํ‘œ๋˜๊ณ  ์žˆ๋‹ค (Jang et al., 2011; Choi et al., 2011; Choi et al., 2014; Kim, 2014).

MgO๋Š” ์†Œ์„ฑ์˜จ๋„์— ๋”ฐ๋ผ 700~1000โ„ƒ์˜ ์ €์˜จ์†Œ์„ฑํ•œ ๊ฒฝ์†Œ (็กฌ็‡’, light-burned MgO), 1000~1500โ„ƒ์˜ ๊ฐ•์—ด (ๅผบ็†ฑ, hard-burned MgO), 1500~2000โ„ƒ ์‚ฌ์ด์˜ ์‚ฌ์†Œ (ๆญป็‡’, dead-burned MgO ๋˜๋Š” heavily burnt MgO) ๋งˆ๊ทธ๋„ค์‹œ์•„๋กœ ๊ตฌ๋ถ„๋œ๋‹ค (Du, 2005; Kim, 2014). ์ด์ค‘์—์„œ light-burned MgO๋Š” reactive MgO๋กœ ๋ช…๋ช…๋˜๊ธฐ๋„ ํ•˜๋Š”๋ฐ, ์ตœ๊ทผ ๊ตญ๋‚ด์™ธ์ ์œผ๋กœ ๋ณดํ†ตํฌํ‹€๋žœ๋“œ์‹œ๋ฉ˜ํŠธ (OPC)์— ํ˜ผํ•ฉํ•˜์—ฌ ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๊ฑด์กฐ์ˆ˜์ถ• ๊ฐ์†Œ ๋˜๋Š” ์žฅ๊ธฐํŒฝ์ฐฝ ์„ฑ์„ ํ–ฅ์ƒ์‹œํ‚ค๋Š” ์—ฐ๊ตฌ๊ฐ€ ์ด๋ฃจ์–ด์ง€๊ธฐ๋„ ํ•˜์˜€๋‹ค. MgO์˜ ์†Œ์„ฑ ์˜จ๋„๋Š” MgO์˜ ์ˆ˜ํ™”๋ฐ˜์‘์— ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š”๋ฐ, Table 1์€ ์†Œ ์„ฑ์˜จ๋„์— ๋”ฐ๋ฅธ MgO์˜ ์ˆ˜ํ™”๋ฐ˜์‘์œจ์„ ๋‚˜ํƒ€๋‚ธ ๊ฒƒ์ด๋‹ค (Du, 2005).

Table 1

Hydration ratio of MgO powder

Hydration Time (days) Burning Temperature

800ยฐC 1200ยฐC 1400ยฐC

1 75.4% 6.5% 4.7%
3 100% 23.4% 9.3%
30 - 94.8% 32.8%
360 - 97.6%

๋ถ„๋ง์„ฑ์ƒ์˜ MgO๋Š” ๋ฌผ๊ณผ ๋ฐ˜์‘ํ•˜์—ฌ ์ตœ์ข…์ ์œผ๋กœ ์ˆ˜์‚ฐํ™”๋งˆ๊ทธ ๋„ค์Š˜ (Mg(OH)2)์ด ๋˜๋Š”๋ฐ, ์ด ๊ณผ์ •์—์„œ MgO๋Š” ๋ถ€ํ”ผํŒฝ์ฐฝ์„ ํ•˜๊ฒŒ ๋œ๋‹ค. ์ด๋Ÿฌํ•œ MgO์˜ ๋ถ€ํ”ผํŒฝ์ฐฝ ํŠน์„ฑ์€ MgO์˜ ๊ฒฐ์ •ํฌ ๊ธฐ์™€ ๋น„ํ‘œ๋ฉด์  ๋“ฑ์ด ์˜ํ–ฅ์„ ๋ฏธ์น˜๊ณ  MgO ์ œ์กฐ์‹œ ์†Œ์„ฑ์˜จ๋„๋ฅผ ์กฐ์ •ํ•˜์—ฌ ์ˆ˜ํ™”๋ฐ˜์‘์„ ์กฐ์ ˆํ•  ์ˆ˜ ์žˆ๋‹ค. ์„ ํ–‰์—ฐ๊ตฌ์— ์˜ํ•˜๋ฉด ์ € ์˜จ์†Œ์„ฑํ•œ MgO๋Š” ์ฝ˜ํฌ๋ฆฌํŠธ์— ์œ ํ•ดํ•œ ์˜ํ–ฅ์—†์ด ์žฅ๊ธฐ์ ์ธ ํŒฝ ์ฐฝ์„ฑ์„ ๊ฐ€์ง„๋‹ค๊ณ  ํ•˜๋Š”๋ฐ, ์ด๋Š” ์ €์˜จ์†Œ์„ฑํ•œ MgO์˜ ์ˆ˜ํ™”์ž‘์šฉ ์€ ๋งค์šฐ ๋Š๋ฆฌ๊ธฐ ๋•Œ๋ฌธ์œผ๋กœ ์•Œ๋ ค์ ธ ์žˆ๋‹ค (Jang et al., 2011; Choi et al., 2011; Du, 2005; Jin et al., 2015).

ํ˜„์žฌ๊นŒ์ง€๋Š” ๋Œ€๋ถ€๋ถ„ light-burned MgO๋ฅผ OPC์— ์ ์šฉํ•œ ์—ฐ ๊ตฌ๋“ค์ด ๋‹ค์ˆ˜ ๋ฐœํ‘œ๋˜๊ณ  ์žˆ๋‹ค. Choi et al. (2011)์€ light-burned MgO์™€ fly ash๋ฅผ ํ˜ผํ•ฉํ•œ OPC์— ๋Œ€ํ•œ ๋‚ด๊ตฌ์„ฑ ์‹คํ—˜์„ ํ†ตํ•ด light-burned MgO์˜ ๋‚ด๊ตฌ์„ฑ ํ–ฅ์ƒ ํšจ๊ณผ๋ฅผ ๋ฐœํ‘œํ•˜์˜€๋‹ค. Li et al. (2014)์€ reactive MgO์™€ silica fume์„ ํ˜ผํ•ฉํ•œ ํŽ˜์ด์Šค ํŠธ ์‹คํ—˜์„ ํ†ตํ•ด ๋ฐ˜์‘ ์ƒ์„ฑ๋ฌผ์งˆ๋กœ M-S-H ์ƒ์„ฑ๊ณผ ํŠน์„ฑ์„ ์—ฐ ๊ตฌํ•˜์˜€๋‹ค. ๊ตญ๋‚ด์—์„œ๋Š” Jang et al. (2011)๊ณผ Choi et al. (2011; 2014)์ด light-burned MgO๋ฅผ ์‚ฌ์šฉํ•œ OPC ์ฝ˜ํฌ๋ฆฌํŠธ์˜ ๊ธฐ์ดˆ ๋ฌผ์„ฑ๊ณผ ๋‚ด๊ตฌ ํŠน์„ฑ์— ๊ด€ํ•œ ์—ฐ๊ตฌ๊ฒฐ๊ณผ๋ฅผ ๋ฐœํ‘œํ•˜์˜€๋‹ค. Gao et al. (2007)์€ 1150โ„ƒ์—์„œ ์†Œ์„ฑํ•œ MgO๋ฅผ OPC์™€ ํ˜ผํ•ฉ ์‚ฌ์šฉํ•˜์—ฌ autoclave ์–‘์ƒ์— ๋”ฐ๋ฅธ ์••์ถ•๊ณผ ํœจ ๊ฐ•๋„ ํŠน์„ฑ์— ๋Œ€ํ•œ ์—ฐ๊ตฌ๋ฅผ ์ˆ˜ํ–‰ํ•˜์˜€๋‹ค. ์ด๋Ÿฌํ•œ ์ €์˜จ ์†Œ์„ฑํ•œ MgO์˜ ํŒฝ์ฐฝ ํŠน์„ฑ์„ ์ด์šฉ ํ•˜์—ฌ OPC์™€ ํ•จ๊ป˜ ์‚ฌ์šฉํ•˜์—ฌ ์ˆ˜์ถ•๋ณด์ƒ ๋˜๋Š” ํŒฝ์ฐฝ ์ฝ˜ํฌ๋ฆฌํŠธ์— ๊ด€ํ•œ ์—ฐ๊ตฌ๊ฐ€ ์ด๋ฃจ์–ด์ง€๊ณ  ์žˆ๋‹ค.

๊ทธ๋Ÿฌ๋‚˜ AAC์—์„œ MgO๋ฅผ ์ ์šฉํ•œ ์—ฐ๊ตฌ๋Š” ์ƒ๋Œ€์ ์œผ๋กœ ๋ฏธํก ํ•˜๋ฉฐ, ์ตœ๊ทผ์—๋Š” ๊ณ ๋กœ์Šฌ๋ž˜๊ทธ๋ฅผ ๊ฒฐํ•ฉ์žฌ๋กœ ์‚ฌ์šฉํ•œ AAC์—์„œ ์Šฌ ๋ž˜๊ทธ ์ค‘๋Ÿ‰์— ๋Œ€ํ•ด reactive MgO๋ฅผ ์น˜ํ™˜ํ•œ ์—ฐ๊ตฌ๊ฐ€ ๋ณด๊ณ ๋˜์—ˆ ๋‹ค (Jin et al., 2015; Fang et al., 2011; Haha et al., 2011).

๋ณธ ์—ฐ๊ตฌ์—์„œ๋Š” AASC (alkali-activated slag cement)์˜ ๊ฑด ์กฐ์ˆ˜์ถ• ์ €๊ฐ์— ๊ด€ํ•œ ๊ธฐ์ดˆ์—ฐ๊ตฌ๋กœ์จ ๊ธฐ์กด์˜ light-burned MgO ์™€ ๋‹ค๋ฅธ ์†Œ์„ฑ์˜จ๋„์— ์˜ํ•ด ์ œ์กฐ๋œ hard-burned MgO์˜ ์น˜ํ™˜ ์— ๋”ฐ๋ฅธ AASC์˜ ๊ฐ•๋„์™€ ๊ฑด์กฐ์ˆ˜์ถ• ํŠน์„ฑ์— ๊ด€ํ•œ ์—ฐ๊ตฌ๋ฅผ ์ˆ˜ํ–‰ ํ•˜์˜€๋‹ค.

2. ์žฌ๋ฃŒ ๋ฐ ์‹คํ—˜

2.1. ์žฌ๋ฃŒ

๋ณธ ์—ฐ๊ตฌ์— ์‚ฌ์šฉ๋œ ๊ณ ๋กœ์Šฌ๋ž˜๊ทธ ๋ฏธ๋ถ„๋ง (ground granulated blast furnace slag; GGBFS)๋Š” ํฌํ•ญ์˜ K์‚ฌ ์ œํ’ˆ์ด๋ฉฐ, ํ™”ํ•™ ์„ฑ๋ถ„์€ XRF (X-ray fluorescence) ๋ถ„์„์„ ํ†ตํ•ด Table 2์— ๋‚˜ ํƒ€๋‚ด์—ˆ๋‹ค. GGBFS์˜ Al/Mg ๋น„๋Š” 4.97, Ca/Mg ๋น„๋Š” 28.15์ธ ๊ฒƒ์„ ์•Œ ์ˆ˜ ์žˆ์œผ๋ฉฐ, GGBFS์˜ ์—ผ๊ธฐ๋„ (basicity) Kb= (CaO+MgO) / (SiO2+Al2O3)๋Š” 1.47์ด๋‹ค (Table 2).

Table 2

Chemical and physical properties of GGBFS

Ground granulated blast furnace slag

Chemical components (%) SiO2 29.67
Al2O3 9.90
Fe2O3 0.68
CaO 56.03
MgO 1.99
TiO2 0.78
MnO 0.37

Physical properties Ig-loss 0.34
Blain (m2/kg) 420
Density (g/mm3) 0.0029

์ž”๊ณจ์žฌ๋Š” ์กฐ๋ฆฝ๋ฅ  (fineness modulus, FM) 2.61, ํ‘œ๋ฉด๊ฑด์กฐ ํฌํ™”์ƒํƒœ ๋ฐ€๋„ 0.0026 g/mm3, ํก์ˆ˜์œจ์€ 1.25์ธ ๊ฐ•๋ชจ๋ž˜๋ฅผ ์‚ฌ ์šฉํ•˜์˜€๋‹ค. ์•Œ์นผ๋ฆฌ ํ™œ์„ฑํ™”์ œ๋Š” S์‚ฌ์˜ ์ˆ˜์‚ฐํ™”์นผ๋ฅจ (potassium hydroxide; KOH, purity > 95.0%)์ด๋‹ค. MgO (purity > 96.0%) ๋Š” S์‚ฌ ์ œํ’ˆ์ด๋‹ค. MgO๋Š” ์†Œ์„ฑ์˜จ๋„๊ฐ€ 1000~1500โ„ƒ์—์„œ ์†Œ ์„ฑํ•œ ๊ฐ•์—ด (ๅผบ็†ฑ, hard-burned MgO) ์ œํ’ˆ์ด๋‹ค.

2.2. ๋ฐฐํ•ฉ ๋ฐ ์‹คํ—˜๋ฐฉ๋ฒ•

MgO๋ฅผ ์น˜ํ™˜ํ•œ AAC์˜ ํŠน์„ฑ์„ ์‚ดํŽด๋ณด๊ธฐ ์œ„ํ•ด MgO์˜ ์น˜ ํ™˜์œจ์„ ๊ฒฐํ•ฉ์žฌ์ธ GGBFS ์ค‘๋Ÿ‰์— ๋Œ€ํ•ด 2~16%๊นŒ์ง€ ์น˜ํ™˜ํ•˜์˜€ ๋‹ค. MgO๋ฅผ ์น˜ํ™˜ํ•˜์ง€ ์•Š์€ ์‹œํ—˜์ฒด๋ฅผ ๋น„๊ต๊ตฐ (control)๋กœ ํ•˜์—ฌ MgO์˜ ์น˜ํ™˜์— ๋”ฐ๋ฅธ ํŠน์„ฑ์„ ์‚ดํŽด๋ณด๊ณ ์ž ํ•˜์˜€๋‹ค. ์น˜ํ™˜๋น„์œจ์€ ๊ธฐ์กด์˜ ๊ตญ๋‚ด์™ธ light-burned MgO์˜ ์—ฐ๊ตฌ๊ฒฐ๊ณผ์™€ ์˜ˆ๋น„์‹คํ—˜์„ ๋ฐ”ํƒ•์œผ๋กœ ๋ณธ ์—ฐ๊ตฌ์˜ ๋ชฉ์ ์ธ ๊ฐ•๋„์™€ ๊ธธ์ด๋ณ€ํ™” ํŠน์„ฑ์„ ๊ฒ€ํ† ํ•  ์ˆ˜ ์žˆ๋Š” ์น˜ํ™˜ ๋ฒ”์œ„๋ฅผ ์„ ์ •ํ•˜์˜€๋‹ค. ํ™œ์„ฑํ™”์ œ์ธ ์ˆ˜์‚ฐํ™”์นผ๋ฅจ (KOH)์˜ ๋†๋„๋Š” ์—ฌ๋Ÿฌ ๊ตญ๋‚ด์™ธ ๋ฌธํ—Œ์˜ ์œ ๋™์„ฑ, ์‘๊ฒฐ ๋ฐ ํ”Œ๋กœ ์šฐ ๋“ฑ์˜ ํŠน์„ฑ๋ณ€ํ™”๋ฅผ ๊ณ ๋ คํ•˜๊ณ , ์˜ˆ๋น„ ์‹คํ—˜์„ ํ†ตํ•ด ๋ณธ ์—ฐ๊ตฌ์— ์‚ฌ์šฉ๋œ ๊ณ ๋กœ์Šฌ๋ž˜๊ทธ ๋ฏธ๋ถ„๋ง์˜ ์•Œ์นผ๋ฆฌ ํ™œ์„ฑํ™”์— ๋”ฐ๋ฅธ ํŠน์„ฑ์„ ์ฐธ๊ณ ํ•˜์—ฌ 2M๊ณผ 4M๋กœ ์ •ํ•˜์˜€๋‹ค. ์ˆ˜์‚ฐํ™”์นผ๋ฅจ (KOH)์€ ์ˆ˜์šฉ ์•ก์—์„œ ๊ฐ•์•Œ์นผ๋ฆฌ๋ฅผ ๋‚˜ํƒ€๋‚ด๋Š” ๋ฌผ์งˆ๋กœ ๊ธฐ์กด์˜ ์„ ํ–‰ AAC ์—ฐ๊ตฌ ์—์„œ NaOH์™€ ํ•จ๊ป˜ ๊ฐ•์•Œ์นผ๋ฆฌ ํ™œ์„ฑํ™”์ œ๋กœ ์‚ฌ์šฉ๋˜์—ˆ๋˜ ์žฌ๋ฃŒ์ด ๋‹ค. Haha et al. (2011)์˜ ์„ ํ–‰ ์—ฐ๊ตฌ์—์„œ NaOH๋Š” ๋ฌผ์œ ๋ฆฌ (waterglass) ๋ณด๋‹ค MgO์˜ ํ™œ์„ฑ์ •๋„๋ฅผ ์ฆ๊ฐ€์‹œํ‚จ๋‹ค๋Š” ์—ฐ๊ตฌ๊ฒฐ ๊ณผ๋„ ์ฐธ๊ณ ํ•˜์—ฌ ์œ ์‚ฌํ•œ ๊ฐ•์•Œ์นผ๋ฆฌ์„ฑ ํ™œ์„ฑํ™”์ œ์ธ KOH๋ฅผ ์„ ์ • ํ•˜์˜€๋‹ค. ์ด๋Š” ๊ธฐ์กด์˜ MgO๋ฅผ ์‚ฌ์šฉํ•œ ๊ตญ๋‚ด์™ธ ์—ฐ๊ตฌ๊ฒฐ๊ณผ์—์„œ KOH๋ฅผ ์‚ฌ์šฉํ•œ ์—ฐ๊ตฌ๊ฒฐ๊ณผ๊ฐ€ ๋ถ€์กฑํ•˜์—ฌ ๋ณธ ์—ฐ๊ตฌ๋ฅผ ํ†ตํ•ด ํ›„์†์—ฐ ๊ตฌ์—์„œ ๊ณ ๋ ค๋  ํ™œ์„ฑํ™”์ œ์˜ ํŠน์„ฑ์— ๊ธฐ์ดˆ์—ฐ๊ตฌ์ž๋ฃŒ๋กœ ์‚ฌ์šฉํ•˜๊ณ  ์ž ์„ ์ •ํ•˜์˜€๋‹ค. KOH๋Š” ํ•ด๋‹น ๋†๋„์— ๋งž์ถฐ ๊ณ„๋Ÿ‰ํ•œ ๋’ค ๋ฐฐํ•ฉ์ˆ˜ ์— ํˆฌ์ž…ํ•˜์—ฌ ํ˜ผํ•ฉํ•œ ๋‹ค์Œ 6์‹œ๊ฐ„ ์ •๋„ ์‹ค๋‚ด ์‹คํ—˜์‹ค์— ์ •์น˜ํ•œ ๋’ค ๋ฐฐํ•ฉ์— ์‚ฌ์šฉํ•˜์˜€๋‹ค.

๋ชจ๋ฅดํƒ€๋ฅด ๋ฐฐํ•ฉ์€ ์ค‘๋Ÿ‰๋น„๋กœ ๊ณ ๋กœ์Šฌ๋ž˜๊ทธ ๋ฏธ๋ถ„๋ง : ์ž”๊ณจ์žฌ๋ฅผ 1.0 : 2.0๋กœ ํ•˜์˜€๊ณ , ๋ฌผ/๊ฒฐํ•ฉ์žฌ (W/B) ๋น„๋Š” 0.5๋ฅผ ๊ณ ๋ คํ•˜์˜€๋‹ค. ๋ฐฐํ•ฉ ์š”์†Œ๋Š” Table 3์— ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค.

Table 3

Mixture properties of AAC mortar

Weight ratio (%)

KOH MgO GGBFS

2M or 4M 0 100
2 98
4 96
6 94
8 92
10 90
12 88
14 86
16 84

๊ฐ๊ฐ์˜ ๋ฐฐํ•ฉ์— ๋”ฐ๋ผ ์žฌ๋ฃŒ๋ฅผ ํ˜ผํ•ฉํ•œ ํ›„ ์••์ถ•๊ฐ•๋„ ์ธก์ •์šฉ 50ร—50ร—50mm ๋ชฐ๋“œ์— ํƒ€์„คํ•˜์—ฌ ์ƒ๋Œ€์Šต๋„ (relative humidity; RH) 75ยฑ5%, 23ยฑ2โ„ƒํ•ญ์˜จํ•ญ์Šต๊ธฐ์— ๋„ฃ๊ณ  1์ผ (24h) ํ›„ ๋ชฐ๋“œ ๋ฅผ ํƒˆํ˜•ํ•˜์˜€๋‹ค. ๋ชฐ๋“œ ํƒˆํ˜• ํ›„ ์••์ถ•๊ฐ•๋„ ์ธก์ •์ผ๊นŒ์ง€ ํ•ญ์˜จํ•ญ์Šต ๊ธฐ (23ยฑ2โ„ƒ, RH 75ยฑ5%)์— ์–‘์ƒํ•˜์˜€์œผ๋ฉฐ, ๊ธธ์ด๋ณ€ํ™” ์‹œํ—˜์ฒด ๋Š” ํƒˆํ˜• ํ›„ RH 50ยฑ5%, 20ยฑ2โ„ƒ์˜ ํ™˜๊ฒฝ์—์„œ ์ธก์ •์žฌ๋ น์ผ๊นŒ์ง€ ๋ณด๊ด€ํ•˜์˜€๋‹ค. ์••์ถ•๊ฐ•๋„๋Š” ๊ฐ ์ธก์ • ์žฌ๋ น (1, 3, 7 ๋ฐ 28์ผ)์—์„œ 3๊ฐœ์˜ ์‹œํ—˜์ฒด์— ๋Œ€ํ•ด ์ธก์ •ํ•˜๊ณ  ๊ทธ ํ‰๊ท ๊ฐ’์„ ์‚ฌ์šฉํ•˜์˜€๋‹ค. ์ดˆ ์ŒํŒŒ ์†๋„ (ultrasonic pulse velocity; UPV)๋Š” PROCEQ CCT-4 ๋ฅผ ์‚ฌ์šฉํ•˜์—ฌ ์žฌ๋ น 1, 3, 7 ๋ฐ 28์ผ์—์„œ ์ธก์ •ํ•˜์˜€๋‹ค. ์ดˆ์ŒํŒŒ ์ธก์ •์€ ์‹œํ—˜์ฒด์˜ ์˜ค๋ฅธ์ชฝ์— ๋ฐœ์ง„์ž๋ฅผ ์™ผ์ชฝ์— ์ˆ˜์‹ ์ž๋ฅผ ์ ‘์ด‰ ์‹œ์ผœ ์†๋„๋ฅผ ์ธก์ •ํ•˜๊ณ , ๋™์ผ ์‹œํ—˜์ฒด์— ๋Œ€ํ•ด ์˜ค๋ฅธ์ชฝ์— ์ˆ˜์‹ ์ž ๋ฅผ ์™ผ์ชฝ์— ๋ฐœ์ง„์ž๋ฅผ ๋‘๊ณ  ์ธก์ •ํ•œ ๊ฐ๊ฐ์˜ ๊ฐ’์„ ํ‰๊ท ํ•˜์—ฌ ๋‚˜ํƒ€ ๋‚ด์—ˆ๋‹ค. ๊ธธ์ด๋ณ€ํ™” ์ธก์ •์€ KS F 2424์˜ ๋‹ค์ด์–ผ๊ฒŒ์ด์ง€ ๋ฐฉ๋ฒ•์œผ ๋กœ ์ธก์ •ํ•˜์˜€๋‹ค. ๊ธธ์ด๋ณ€ํ™” ์ธก์ •์šฉ ์‹œํ—˜์ฒด๋Š” 40ร—40ร—160mm ๋ชฐ ๋“œ๋ฅผ ์‚ฌ์šฉํ•˜์˜€๊ณ , ๊ธธ์ด๋ณ€ํ™”๋Š” 91์ผ๊นŒ์ง€ ์ธก์ •ํ•˜์˜€๋‹ค.

SEM (scanning electron microscopy)์€ Hitachi FE-SEM S-4700 ์žฅ๋น„๋ฅผ ์‚ฌ์šฉํ•˜์˜€์œผ๋ฉฐ, ์‹œํŽธ์€ ๊ฐ•๋„ ์ธก์ • ํ›„ ํŒŒ์‡„๋œ ์‹œํ—˜์ฒด ์กฐ๊ฐ์„ ์•„์„ธํ†ค์— ๋„ฃ์–ด ์ˆ˜ํ™”์ •์ง€ ์‹œํ‚จ ๋‹ค์Œ ๊ฑด์กฐํ•˜์—ฌ ์ธก์ •ํ•˜์˜€๋‹ค.

3. ๊ฒฐ๊ณผ ๋ฐ ๊ณ ์ฐฐ

3.1. ์••์ถ•๊ฐ•๋„

Fig. 1์€ KOH์˜ ๋†๋„์™€ MgO์˜ ์น˜ํ™˜๋น„์œจ์— ๋”ฐ๋ฅธ AASC ์˜ ์••์ถ•๊ฐ•๋„ ๊ฒฐ๊ณผ๋ฅผ ๋‚˜ํƒ€๋‚ธ ๊ฒƒ์ด๋‹ค.

2M KOH ๋†๋„์—์„œ 1์ผ ๊ฐ•๋„๋Š” MgO๋ฅผ ์น˜ํ™˜ํ•˜์ง€ ์•Š์€ ์‹œ ํ—˜์ฒด๋ณด๋‹ค MgO๋ฅผ ์น˜ํ™˜ํ•œ ์‹œํ—˜์ฒด์˜ ๊ฐ•๋„๊ฐ€ ๋‚ฎ๊ฒŒ ๋‚˜ํƒ€๋‚ฌ์ง€๋งŒ, 3์ผ ์ดํ›„๋ถ€ํ„ฐ๋Š” MgO๋ฅผ ์น˜ํ™˜ํ•˜์ง€ ์•Š์€ ์‹œํ—˜์ฒด ๋ณด๋‹ค ๋†’์€ ๊ฐ• ๋„๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค (Fig. 1(a)). ์ „์ฒด์ ์ธ ๊ฐ•๋„ ํŠน์„ฑ์€ MgO ์น˜ ํ™˜์œจ 4%๊นŒ์ง€๋Š” ๊ฐ•๋„ ์ฆ๊ฐ€ํšจ๊ณผ๊ฐ€ ๋ฏธ๋ฏธํ•˜์˜€์œผ๋‚˜ 4% ์ดํ›„๋ถ€ํ„ฐ 8%๊นŒ์ง€๋Š” ๋‹ค์†Œ ๋†’์€ ๊ฐ•๋„์ฆ๊ฐ€๊ฐ€ ๋‚˜ํƒ€๋‚ฌ๊ณ  ์ดํ›„๋ถ€ํ„ฐ ๊ฐ•๋„ ์ฆ ๊ฐ€ ๊ฒฝํ–ฅ์€ ์ ์ฐจ ๋‘”ํ™”๋˜์—ˆ๋‹ค.

Fig. 1.

Compressive strength of samples

JKSMI-19-39_F1.jpg

4M KOH ๋†๋„์—์„œ 1์ผ ๊ฐ•๋„๋Š” MgO๋ฅผ ์น˜ํ™˜ํ•œ ์‹œํ—˜์ฒด์™€ MgO๋ฅผ ์น˜ํ™˜ํ•˜์ง€ ์•Š์€ ์‹œํ—˜์ฒด์˜ ๊ฐ•๋„ ์ฐจ์ด๋Š” ๋ฏธ๋ฏธํ•˜์˜€์œผ๋‚˜, 3์ผ ์ดํ›„ ๊ฐ•๋„๋Š” ๊ธ‰๊ฒฉํžˆ ์ฆ๊ฐ€ํ•˜๊ณ  ์žˆ์—ˆ๋‹ค (Fig. 1(b)). 4M KOH ๋†๋„์˜ MgO ์น˜ํ™˜ ์‹œํ—˜์ฒด๋Š” MgO๊ฐ€ 12% ์น˜ํ™˜์œจ์ด ๋  ๋•Œ๊นŒ ์ง€ ๊ธ‰๊ฒฉํ•œ ๊ฐ•๋„ ์ฆ๊ฐ€๋ฅผ ๋ณด์ด๋‹ค๊ฐ€ 12% ์น˜ํ™˜์œจ ์ดํ›„ ๊ฐ•๋„๋Š” ๋‹ค์†Œ ๊ฐ์†Œํ•˜๋Š” ๊ฒฝํ–ฅ์„ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ์—ˆ๋‹ค. 2M์™€ 4M KOH ๋† ๋„์™€ MgO์˜ ์น˜ํ™˜์œจ์— ๋”ฐ๋ฅธ ์‹œํ—˜์ฒด์˜ ๊ฐ•๋„ ํŠน์„ฑ์—์„œ ๋ณผ ๋•Œ MgO์˜ ์น˜ํ™˜์€ AASC์˜ ๊ฐ•๋„ ํ–ฅ์ƒ์— ์˜ํ–ฅ์„ ๋ฏธ์น˜๋ฉฐ, KOH ์˜ ๋†๋„์— ๋”ฐ๋ผ ์ตœ์  MgO์˜ ์น˜ํ™˜์œจ์˜ ๋ฒ”์œ„๊ฐ€ ์กด์žฌํ•  ๊ฒƒ์œผ ๋กœ ํŒ๋‹จ๋œ๋‹ค.

2M KOH์—์„œ 8% MgO ์‹œํ—˜์ฒด์˜ 28์ผ ๊ฐ•๋„๊ฐ€ 34.1MPa ๋กœ MgO๋ฅผ ์น˜ํ™˜ํ•˜์ง€ ์•Š์€ ์‹œํ—˜์ฒด๋ณด๋‹ค 33.2% ๊ฐ•๋„๊ฐ€ ํ–ฅ์ƒ๋˜์—ˆ ๊ณ , 4M KOH์—์„œ๋Š” 12% MgO ์‹œํ—˜์ฒด๊ฐ€ 47.4MPa๋กœ 43.6% ์˜ ๊ฐ•๋„ ํ–ฅ์ƒ ํšจ๊ณผ๊ฐ€ ๋‚˜ํƒ€๋‚ฌ๋‹ค. KOH์˜ ๋†๋„์™€ MgO ์น˜ํ™˜์œจ ์˜ ์ฐจ์ด์— ๋”ฐ๋ฅธ ๊ฐ•๋„ ํŠน์„ฑ์€ OH-์ด์˜จ์— ์˜ํ•œ ์ˆ˜์šฉ์•ก์˜ ๊ฐ•์•Œ ์นผ๋ฆฌ ํ™˜๊ฒฝ์—์„œ Mg2+ ์ด์˜จ์˜ ๋ฐ˜์‘์„ฑ์— ๋”ฐ๋ฅธ ์˜ํ–ฅ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

ํŠนํžˆ 1์ผ ๊ฐ•๋„๋ฅผ ๋น„๊ตํ•˜๋ฉด ์ƒ๋Œ€์ ์œผ๋กœ ๋†๋„๊ฐ€ ๋‚ฎ์€ 2M KOH์—์„œ๋Š” MgO์˜ ์น˜ํ™˜์œจ์ด ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ๊ฐ•๋„ ์ €ํ•˜๊ฐ€ ๋‚˜ํƒ€๋‚ฌ์ง€๋งŒ, 4M์—์„œ๋Š” ๊ฐ•๋„์˜ ๋ณ€ํ™”๊ฐ€ ๊ฑฐ์˜ ์—†๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ ํƒ€๋‚ฌ๋‹ค. ์ด๋ฅผ ํ†ตํ•ด 2M KOH ๋†๋„๋Š” 4M KOH ๋†๋„์— ๋น„ํ•ด ์ดˆ๊ธฐ ์ˆ˜ํ™”๊ณผ์ •์—์„œ MgO๋ฅผ ํ™œ์„ฑํ™”์‹œ์ผœ ๋ฐ˜์‘ ์ƒ์„ฑ๋ฌผ์งˆ์„ ๋งŒ๋“œ ๋Š” ํšจ๊ณผ๊ฐ€ ์ƒ๋Œ€์ ์œผ๋กœ ๋‚ฎ์€ ๊ฒƒ์œผ๋กœ ์ƒ๊ฐ๋œ๋‹ค. ๋”ฐ๋ผ์„œ AASC ์—์„œ MgO์˜ ๋ฐ˜์‘์„ฑ์„ ์ฆ๊ฐ€์‹œํ‚ค๊ธฐ ์œ„ํ•ด์„œ๋Š” ํ•จ๊ป˜ ์‚ฌ์šฉํ•˜๋Š” ํ™œ์„ฑํ™”์ œ์˜ ๋†๋„๋„ ํ•จ๊ป˜ ๊ณ ๋ คํ•ด์•ผ ํ•  ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

์••์ถ•๊ฐ•๋„ ๊ฒฐ๊ณผ์—์„œ Haha et al. (2011)์€ MgO ํ•จ์œ ์œจ์ด ์„œ๋กœ ๋‹ค๋ฅธ ๊ณ ๋กœ์Šฌ๋ž˜๊ทธ 3์ข…๋ฅ˜๋ฅผ NaOH์™€ ๋ฌผ์œ ๋ฆฌ (waterglass) ๋กœ ํ™œ์„ฑํ™”์‹œํ‚ค๋Š” ์‹คํ—˜์—์„œ, ๊ณ ๋กœ์Šฌ๋ž˜๊ทธ ์ž์ฒด์˜ MgO ํ•จ์œ ์œจ ์ด 8%์—์„œ 13%๋กœ ์ฆ๊ฐ€ํ•˜๋ฉด NaOH์— ์˜ํ•œ AASC์˜ ๊ฐ•๋„๊ฐ€ ๊ฐ์†Œํ•˜๋Š” ๊ฒฐ๊ณผ๊ฐ€ ๋‚˜ํƒ€๋‚œ๋‹ค๊ณ  ๋ณด๊ณ ํ•˜์˜€๋‹ค. ๋˜ํ•œ Haha et al. (2011)์€ OPC-slag ์‹œ์Šคํ…œ์—์„œ๋Š” MgO์˜ ์ถ”๊ฐ€๊ฐ€ ๊ฐ•๋„ ๊ฐ์†Œ ๋ฅผ ๊ฐ€์ ธ์˜ค์ง€๋งŒ AASC์—์„œ๋Š” ๊ฐ•๋„๋ฅผ ์ฆ๊ฐ€์‹œํ‚จ๋‹ค๊ณ  ํ•˜์˜€๋‹ค. ๋”ฐ๋ผ์„œ ์ ์ • ์ˆ˜์ค€์˜ ์•Œ์นผ๋ฆฌ ํ™˜๊ฒฝ์ด MgO์˜ ํ™œ์„ฑํ™”๋ฅผ ์ฆ๋Œ€์‹œ ์ผœ ๊ฒฐํ•ฉ์žฌ์™€์˜ ๋ฐ˜์‘์„ฑ์„ ํ–ฅ์ƒ์‹œ์ผœ ๊ฐ•๋„์— ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š” ๊ฒƒ ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

Fig. 2๋Š” Al/Mg์™€ Ca/Mg ์„ฑ๋ถ„๋น„์— ๋”ฐ๋ฅธ 28์ผ ์••์ถ•๊ฐ•๋„๊ฐ’ ์˜ ๋ถ„ํฌ๋ฅผ ๋‚˜ํƒ€๋‚ด์—ˆ๋‹ค. Al/Mg์™€ Ca/Mg ์„ฑ๋ถ„๋น„๋Š” Table 2์˜ GGBFS ์„ฑ๋ถ„๊ณผ MgO์˜ ์น˜ํ™˜์— ๋”ฐ๋ผ ์ถ”๊ฐ€๋œ MgO์˜ ์–‘์„ ๊ณ„์‚ฐํ•œ ๊ฒƒ์ด๋‹ค. Fig. 2(a)์—์„œ Al/Mg ๋น„๊ฐ€ 0.47~0.75๋ฒ”์œ„์— ์„œ KOH์˜ ๋†๋„์— ๊ด€๊ณ„์—†์ด ์ƒ๋Œ€์ ์œผ๋กœ ๋†’์€ ๊ฐ•๋„ ๋ฐœํ˜„์ด ๋‚˜ํƒ€๋‚˜๊ณ  ์žˆ๋‹ค. Fig. 2(b)์—์„œ๋Š” Ca/Mg ๋น„๊ฐ€ 2M KOH์ธ ์‹œ ํ—˜์ฒด๋Š” 2.66~4.27๋ฒ”์œ„์—์„œ ๋†’์€ ๊ฐ•๋„๊ฐ€ ๋ฐœํ˜„๋˜๊ณ  ์žˆ๊ณ , 4M KOH๋Š” 2.66~3.58 ๋ฒ”์œ„์—์„œ ๋†’์€ ๊ฐ•๋„๊ฐ€ ๋ฐœํ˜„๋˜๊ณ  ์žˆ์—ˆ๋‹ค. Fig. 2์— ๋‚˜ํƒ€๋‚œ Al/Mg ๊ทธ๋ฆฌ๊ณ  Ca/Mg ๋น„์™€ ์••์ถ•๊ฐ•๋„์˜ ํŠน ์„ฑ์„ ํ†ตํ•ด MgO์˜ ์น˜ํ™˜์— ๋”ฐ๋ฅธ ๊ฐ•๋„ ํ–ฅ์ƒ ํšจ๊ณผ๊ฐ€ ๋ฐœํ˜„๋˜๋Š” GGBFS์™€ MgO ํ˜ผํ•ฉ์— ๋”ฐ๋ฅธ ์„ฑ๋ถ„๋“ค์˜ ์ผ์ • ๋ฒ”์œ„๊ฐ€ ์žˆ์„ ๊ฒƒ ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

Fig. 2.

Compressive strength and Al/Mg ratio and Ca/Mg ratio

JKSMI-19-39_F2.jpg

3.2. UPV (ultrasonic pulse velocity)

์ดˆ์ŒํŒŒ ์†๋„ ์ธก์ • ๊ฒฐ๊ณผ๋Š” Fig. 3๊ณผ ๊ฐ™๋‹ค.

Fig. 3.

Ultrasonic pulse velocity (UPV)

JKSMI-19-39_F3.jpg

2M KOH ๋†๋„์˜ ์‹œํ—˜์ฒด๋Š” MgO์˜ ์น˜ํ™˜์œจ์ด 8%๊นŒ์ง€๋Š” ๋น„์Šทํ•œ ์ดˆ์ŒํŒŒ ์†๋„๊ฐ’์„ ๋ณด์ด๋‹ค๊ฐ€ MgO 8% ์น˜ํ™˜์œจ์—์„œ ์ดˆ ์ŒํŒŒ ์†๋„๊ฐ€ ์ฆ๊ฐ€ํ•œ ๋’ค ๋‹ค์‹œ 10%๋ถ€ํ„ฐ ๊ฐ์†Œํ•˜๋Š” ๋ชจ์Šต์„ ๋ณด์ด ๊ณ  ์žˆ๋‹ค (Fig. 3(a)). 4M KOH์—์„œ๋„ MgO 10% ์น˜ํ™˜์œจ๊นŒ์ง€ ์ฆ๊ฐ€ํ•˜๋˜ ์ดˆ์ŒํŒŒ ์†๋„๊ฐ€ 10% ์ดํ›„ ๊ฐ’์˜ ๋ณ€๋™์ด ๊ฑฐ์˜ ์—†๋Š” ๊ฒƒ์œผ๋กœ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ์—ˆ๋‹ค (Fig. 3(b)).

์ด๋Ÿฌํ•œ ์ดˆ์ŒํŒŒ ์†๋„์˜ ๊ฒฐ๊ณผ๋Š” ์ด์ „์— ์–ธ๊ธ‰ํ•œ ์••์ถ•๊ฐ•๋„ ๊ฒฐ๊ณผ ์™€ ์ƒ๋‹นํžˆ ์œ ์‚ฌํ•œ ๋ณ€ํ™”ํŠน์„ฑ์„ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ๋‹ค. ํŠนํžˆ 4M KOH ์˜ ๊ฒฝ์šฐ 2M KOH ๋†๋„์—์„œ์˜ MgO ์‹œํ—˜์ฒด๋“ค๋ณด๋‹ค ์ดˆ๊ธฐ์žฌ๋ น ์ธ 1์ผ์—์„œ์˜ UPV๊ฐ€ ์ƒ๋‹นํžˆ ๋†’๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ 4M KOH ์‹œํ—˜์ฒด์˜ 3์ผ๊ณผ 7์ผ์—์„œ์˜ UPV ์ฆ๊ฐ€๋Ÿ‰์€ 2M KOH ์™€ ๋น„๊ตํ•˜์—ฌ ์ƒ๋Œ€์ ์œผ๋กœ ์ฆ๊ฐ€์ •๋„๊ฐ€ ๋‚ฎ์•˜์ง€๋งŒ 28์ผ์—์„œ์˜ UPV ์ฆ๊ฐ€๋Ÿ‰์€ ์˜คํžˆ๋ ค 4M KOH๊ฐ€ 2M KOH ๋†๋„์—์„œ ๋ณด ๋‹ค ๋†’์€ ๊ฒฝํ–ฅ์„ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ์—ˆ๋‹ค. ์ด๋Ÿฌํ•œ ์ดˆ์ŒํŒŒ ์†๋„์˜ ์ฆ ๊ฐ€์–‘์ƒ์˜ ์ฐจ์ด๋Š” ์••์ถ•๊ฐ•๋„ ํŠน์„ฑ๊ณผ ๋น„๊ตํ•˜์—ฌ ๋ณด๋ฉด, 7์ผ์—์„œ 28์ผ ์••์ถ•๊ฐ•๋„์˜ ๊ฐ•๋„ ์ฆ๊ฐ€์œจ์ด 2M KOH ๋†๋„๋ณด๋‹ค 4M KOH ๋†๋„์—์„œ ๋” ํฐ ๊ฒƒ์„ ํ†ตํ•ด์„œ๋„ ๋‚˜ํƒ€๋‚œ๋‹ค.

๋”ฐ๋ผ์„œ 2M KOH ๋ณด๋‹ค ์ƒ๋Œ€์ ์œผ๋กœ ๋” ๋†’์€ ๋†๋„์ธ 4M KOH๋Š” ์ดˆ๊ธฐ์žฌ๋ น (1์ผ ๋ฐ 3์ผ)์—์„œ MgO์˜ ๋ฐ˜์‘์„ฑ์„ ํ–ฅ์ƒ ์‹œํ‚ค๊ณ , 28์ผ์—์„œ ๋ฏธ๋ฐ˜์‘ MgO์˜ ์ˆ˜ํ™”๋ฐ˜์‘์—๋„ ์œ ํšจํ•œ ์˜ํ–ฅ ์„ ๋ฏธ์น˜๋Š” ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

3.3. ๊ธธ์ด๋ณ€ํ™”

Fig. 4์—๋Š” KOH์˜ ๋†๋„์™€ MgO์˜ ์น˜ํ™˜์œจ์— ๋”ฐ๋ฅธ ์‹œํ—˜์ฒด ์˜ ๊ธธ์ด๋ณ€ํ™”๋ฅผ ์ธก์ •ํ•œ ๊ฒƒ์ด๋‹ค. 2M KOH์™€ 4M KOH ๋†๋„ ๋ชจ๋‘์—์„œ MgO์˜ ์น˜ํ™˜์œจ์ด ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ๊ฑด์กฐ์ˆ˜์ถ•์ด ๊ฐ์†Œ ํ•˜๋Š” ๊ฒƒ์„ ๋ณผ ์ˆ˜ ์žˆ์—ˆ๋‹ค.

Fig. 4.

Drying shrinkage

JKSMI-19-39_F4.jpg

ํŠนํžˆ 4M KOH ๋†๋„์—์„œ MgO์˜ ์น˜ํ™˜์— ๋”ฐ๋ฅธ ๊ฑด์กฐ์ˆ˜์ถ• ์ €๊ฐ์€ 2M KOH ๋†๋„ ๋ณด๋‹ค ์ƒ๋Œ€์ ์œผ๋กœ ๋†’์€ ์ €๊ฐํšจ๊ณผ๋ฅผ ๋‚˜ ํƒ€๋‚ด๊ณ  ์žˆ์—ˆ๋‹ค. 4M KOH์˜ ๋†๋„์—์„œ MgO์˜ ์น˜ํ™˜์— ๋”ฐ๋ฅธ ๊ฑด์กฐ์กฐ์ถ•์€ MgO์˜ ์น˜ํ™˜์œจ์ด ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ์ดˆ๊ธฐ ์ธก์ •์‹œ์  ์—์„œ๋ถ€ํ„ฐ ๊ฑด์กฐ์ˆ˜์ถ•์˜ ๋ฐœ์ƒ์ด ๊ฑฐ์˜ ์—†๊ฑฐ๋‚˜ ์ƒ๋‹นํžˆ ์ ์€ ์ˆ˜์ถ• ํŠน์„ฑ์„ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ์—ˆ๋‹ค. ์ด๋Š” 2M KOH ๋ณด๋‹ค ์ƒ๋Œ€์ ์œผ๋กœ ๋†’์€ ๋†๋„์ธ 4M KOH์—์„œ MgO๊ฐ€ Mg(OH)2๋กœ์˜ ๋ณ€ํ™˜์„ ์ด‰์ง„์‹œ์ผœ ์ดˆ๊ธฐ์žฌ๋ น์—์„œ๋ถ€ํ„ฐ ํŒฝ์ฐฝ์„ฑ์ด ๋ฐœํ˜„๋˜์–ด ๊ฑด์กฐ์ˆ˜์ถ•์„ ์ €๊ฐ์‹œํ‚ค๋Š” ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

MgO์˜ ์น˜ํ™˜์œจ์ด ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ๊ฑด์กฐ์ˆ˜์ถ•์ด ๊ฐ์†Œํ•˜๋Š” ๊ฒฝ ํ–ฅ์€ light-burn MgO๋ฅผ ์‚ฌ์šฉํ•œ Jang et al. (2011) ์˜ ์—ฐ๊ตฌ๊ฒฐ ๊ณผ์™€ ์œ ์‚ฌํ•จ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค. ์ด๋Š” ์†Œ์„ฑ์˜จ๋„๊ฐ€ ๋‹ค๋ฅธ light-burned ์™€ hard-burned MgO์˜ ๊ฑด์†Œ์ˆ˜์ถ• ๊ฐ์†Œ ๊ฒฝํ–ฅ์€ ์„œ๋กœ ์œ ์‚ฌํ•˜ ๊ฒŒ ๋‚˜ํƒ€๋‚˜๋Š” ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค. Fang et al. (2011)์€ 10%์™€ 20% NaOH ๋†๋„์— lightly-burn MgO์™€ ํ”Œ๋ผ์ด์• ์‹œ (fly ash) ๋ฅผ ์น˜ํ™˜ํ•œ AASC์˜ ๊ฑด์กฐ์ˆ˜์ถ• ์‹คํ—˜๊ฒฐ๊ณผ์—์„œ๋„ MgO์˜ ์น˜ํ™˜ ์œจ์ด ์ฆ๊ฐ€ํ•จ์— ๋”ฐ๋ผ ๊ฑด์กฐ์ˆ˜์ถ•์ด ๊ฐ์†Œํ•˜๊ณ  ์žˆ๋Š” ์—ฐ๊ตฌ๊ฒฐ๊ณผ๋ฅผ ๋ฐœํ‘œํ•˜์˜€๋‹ค.

Table 4๋Š” KOH ๋†๋„์™€ MgO ์น˜ํ™˜์œจ์— ๋”ฐ๋ฅธ ๊ฐ๊ฐ์˜ ์‹œํ—˜ ์ฒด์˜ 91์ผ ์ตœ์ข… ๊ฑด์กฐ์ˆ˜์ถ•์œจ์„ ์ •๋ฆฌํ•œ ๊ฒƒ์ด๋‹ค. ํŠนํžˆ 4% MgO ์น˜ํ™˜์œจ๋ถ€ํ„ฐ 4M KOH์˜ ๋†๋„์—์„œ ์น˜ํ™˜๋œ MgO์˜ ๊ฑด์กฐ์ˆ˜์ถ• ์ €๊ฐ์œจ์ด 2M KOH ๋ณด๋‹ค ์•ฝ 12.5~70% ์ •๋„ ๋” ํฐ ๊ฐ์†Œํšจ๊ณผ ๊ฐ€ ์žˆ์—ˆ๋‹ค. ์ด๋ฅผ ํ†ตํ•ด ์ƒ๋Œ€์ ์œผ๋กœ ๋†’์€ ํ™œ์„ฑํ™”์ œ ๋†๋„์—์„œ MgO์˜ ํ™œ์„ฑํ™” ๋ฐ˜์‘์ด ์ฆ๊ฐ€ํ•˜์—ฌ Mg(OH)2๋กœ์˜ ๋ณ€ํ™”๊ฐ€ ์ด‰์ง„ ๋˜๊ณ , ๋”ฐ๋ผ์„œ ํŒฝ์ฐฝ์„ฑ๋Šฅ์˜ ๋ฐœํ˜„์ด ํ–ฅ์ƒ๋˜๋Š” ๊ฒƒ์œผ๋กœ ์ƒ๊ฐ๋œ๋‹ค.

Table 4

Ultimate length change ratio at 91 days

Length change (%)

MgO Content (%) 2M KOH 4M KOH

0 -0.2369 -0.2810
2 -0.2285 -0.2389
4 -0.2258 -0.1974
6 -0.2205 -0.1856
8 -0.2145 -0.1482
10 -0.1916 -0.1268
12 -0.1959 -0.1148
14 -0.1884 -0.0692
16 -0.1862 -0.0541

3.4. SEM (scanning electron microscopy)

Fig. 5๋Š” 2M๊ณผ 4M KOH ๋†๋„์—์„œ MgO๋ฅผ ์น˜ํ™˜ํ•˜์ง€ ์•Š ์€ ์‹œํ—˜์ฒด์™€ ๊ฐ•๋„๋ฐœํ˜„์ด ๊ฐ€์žฅ ๋†’์€ ์‹œํ—˜์ฒด์˜ SEM/EDS (Energy Dispersive Spectroscopy) ๋ถ„์„ ์ด๋ฏธ์ง€์ด๋‹ค. MgO๋ฅผ ์น˜ํ™˜ํ•˜ ์ง€ ์•Š์€ ์‹œํ—˜์ฒด์˜ ๊ฒฝ์šฐ ๊ด€์ธก๋ถ€๋ถ„ ์ „์ฒด์— ๊ฑธ์ณ ๋‘๊ป˜๊ฐ€ ์–‡์€ ํŒ์ƒ์˜ ๋ฐ˜์‘๋ฌผ์งˆ๋“ค์ด ๋‹ค์ˆ˜ ์ƒ์„ฑ๋œ ๊ฒƒ์„ ๊ด€์ฐฐ ํ•  ์ˆ˜ ์žˆ์—ˆ๋‹ค (Fig. 5(a), 5(b)). ๊ทธ๋Ÿฌ๋‚˜ MgO๋ฅผ ์น˜ํ™˜ํ•œ ์‹œํ—˜์ฒด ์ค‘ ์ตœ๊ณ  ๊ฐ•๋„ ๊ฐ€ ๋ฐœ์ƒํ•œ ์‹œํ—˜์ฒด์˜ ๊ฒฝ์šฐ (2M KOH + 8% MgO, 4M KOH + 12% MgO) ํŒ์ƒ์˜ ๋ฐ˜์‘์ƒ์„ฑ๋ฌผ์งˆ๋“ค์€ ๊ฑฐ์˜ ์‚ฌ๋ผ์ง€๊ณ  ์น˜๋ฐ€ํ•œ ์กฐ์ง์˜ ๋ฐ˜์‘ ์ƒ์„ฑ๋ฌผ์งˆ๋“ค์ด ๊ด€์ฐฐ๋˜์—ˆ๋‹ค (Fig. 5(c), 5(d)).

Fig. 5.

SEM micrograph and EDX analysis at 28 days

JKSMI-19-39_F5.jpg

EDS๋ถ„์„์„ ํ†ตํ•ด ๊ด€์ฐฐ๋œ MgO๋ฅผ ์น˜ํ™˜ํ•œ AASC์˜ ์ˆ˜ํ™” ์ƒ ์„ฑ๋ฌผ์งˆ๋“ค์€ MgO๋ฅผ ์น˜ํ™˜ํ•˜์ง€ ์•Š์€ ์‹œํ—˜์ฒด์™€ ๋น„๊ตํ•˜์—ฌ ์ƒ๋Œ€ ์ ์œผ๋กœ ์น˜๋ฐ€ํ•œ ์กฐ์ง์„ ๊ตฌ์„ฑํ•˜๊ณ  ์žˆ๋Š” ๊ฒƒ์„ ๋ณผ ์ˆ˜ ์žˆ๋‹ค. ์ด๋Ÿฌ ํ•œ ๊ฒฐ๊ณผ๋Š” Jang et al. (2011), Choi et al. (2011, 2014)์ด ์‹ค ํ—˜ํ•œ lightly-burn MgO ๋ถ„๋ง์„ ์น˜ํ™˜ํ•œ OPC์˜ SEM/EDS์— ๋‚˜ํƒ€๋‚œ ๊ฒƒ๊ณผ ์œ ์‚ฌํ•œ ๊ฒฝํ–ฅ์„ ๋‚˜ํƒ€๋‚ด๊ณ  ์žˆ์Œ์„ ์•Œ ์ˆ˜ ์žˆ๋‹ค.

4. ๊ฒฐ ๋ก 

Hard-burned MgO๋ฅผ ์น˜ํ™˜ํ•œ ๊ณ ๋กœ์Šฌ๋ž˜๊ทธ ๋ฏธ๋ถ„๋ง์„ KOH ๋กœ ํ™œ์„ฑํ™”์‹œํ‚จ AASC์˜ ๊ฐ•๋„์™€ ๊ฑด์กฐ์ˆ˜์ถ• ํŠน์„ฑ์— ๊ด€ํ•œ ์—ฐ๊ตฌ ๊ฒฐ๊ณผ ๋‹ค์Œ๊ณผ ๊ฐ™์€ ๊ฒฐ๋ก ์„ ์–ป์—ˆ๋‹ค.

  1. MgO์˜ ์น˜ํ™˜์œจ์ด ์ฆ๊ฐ€ํ• ์ˆ˜๋ก ๊ฐ•๋„๋Š” ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ๋˜ ํ•œ MgO์˜ ๊ฐ•๋„ ํ–ฅ์ƒ ํšจ๊ณผ๋Š” ํ™œ์„ฑํ™”์ œ์ธ KOH์˜ ๋† ๋„๊ฐ€ 2M์—์„œ 4M๋กœ ๋†’์•„์ง์— ๋”ฐ๋ผ ๋”์šฑ ์ฆ๊ฐ€ํ•˜์˜€๋‹ค. ์ด๋Š” ์•Œ์นผ๋ฆฌ ํ™œ์„ฑํ™”์ œ์˜ ๋†๋„๊ฐ€ MgO์˜ ๋ฐ˜์‘์„ฑ์„ ์ฆ ๊ฐ€์‹œํ‚ค๋Š”๋ฐ ์˜ํ–ฅ์„ ๋ฏธ์น˜๋Š” ๊ฒƒ์œผ๋กœ ์ƒ๊ฐ๋œ๋‹ค. ๋”ฐ๋ผ์„œ MgO๋ฅผ AASC์— ์‚ฌ์šฉํ•  ๊ฒฝ์šฐ ํ™œ์„ฑํ™”์ œ์˜ ์ข…๋ฅ˜์™€ ๋† ๋„์— ๋”ฐ๋ฅธ ๊ฐ•๋„ํ–ฅ์ƒ ํšจ๊ณผ๋„ ํ•จ๊ป˜ ๊ณ ๋ คํ•˜์—ฌ์•ผ ํ•  ๊ฒƒ์œผ ๋กœ ํŒ๋‹จ๋œ๋‹ค.

  2. MgO์˜ ์น˜ํ™˜์€ AASC์˜ ๋ฐ˜์‘ ์ƒ์„ฑ๋ฌผ์งˆ๋“ค์˜ ๊ตฌ์กฐ๋ฅผ ์น˜๋ฐ€ํ•˜๊ฒŒ ๋งŒ๋“ค์–ด ์ดˆ์ŒํŒŒ ์†๋„์™€ ๊ฐ•๋„ ํ–ฅ์ƒ์— ์˜ํ–ฅ์„ ์ฃผ๋Š” ๊ฒƒ์œผ๋กœ ์ƒ๊ฐ๋œ๋‹ค. ์žฌ๋ น์˜ ์ฆ๊ฐ€์— ๋”ฐ๋ฅธ AASC์˜ ์‚ฌ์šฉ๋ชฉ์ ๊ณผ ์šฉ๋„์— ์ ํ•ฉํ•œ ์ ์ • ์ˆ˜์ค€์˜ MgO์˜ ์น˜ํ™˜ ์œจ์„ ๊ณ ๋ คํ•  ํ•„์š”๊ฐ€ ์žˆ์„ ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

  3. MgO๋ฅผ ์น˜ํ™˜ํ•œ ๊ณ ๋กœ์Šฌ๋ž˜๊ทธ ๋ฏธ๋ถ„๋ง์€ AASC ๋ฐฐํ•ฉ์—์„œ ๊ฑด์กฐ์ˆ˜์ถ•์„ ๊ฐ์†Œ์‹œํ‚ค๋Š” ํšจ๊ณผ๊ฐ€ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ํŠนํžˆ 4M KOH ์˜ AASC๊ฐ€ 2M KOH ๋ณด๋‹ค ๊ฑด์กฐ์ˆ˜์ถ• ์ €๊ฐํšจ๊ณผ๊ฐ€ ํฌ ๊ฒŒ ๋‚˜ํƒ€๋‚ฌ๋‹ค. ์ด๋ฅผ ํ†ตํ•ด AASC์—์„œ MgO๋Š” ์ดˆ๊ธฐ์™€ ์žฅ ๊ธฐ ์žฌ๋ น์—์„œ ๊ฑด์กฐ์ˆ˜์ถ• ์ €๊ฐ์— ํšจ๊ณผ๊ฐ€ ์žˆ์Œ์„ ์•Œ ์ˆ˜ ์žˆ ์—ˆ๋‹ค. ๋˜ํ•œ ๊ฑด์กฐ์ˆ˜์ถ• ์ €๊ฐ์œจ์„ ๋†’์ด๊ธฐ ์œ„ํ•ด์„œ๋Š” ์ผ์ • ์ˆ˜์ค€ ์ด์ƒ์˜ ๋†’์€ ํ™œ์„ฑํ™”์ œ ๋†๋„์™€ MgO์˜ ์น˜ํ™˜์œจ์ด ํ•„์š”ํ•  ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

  4. ๊ธฐ์กด์˜ OPC๋ฅผ ์ค‘์‹ฌ์œผ๋กœ ํ•œ light-burned MgO์˜ ํŠน์„ฑ ์—ฐ๊ตฌ๊ฒฐ๊ณผ์™€ ๋น„๊ตํ•ด ๋ณผ ๋•Œ KOH๋กœ ํ™œ์„ฑํ™”๋œ AASC์— ์„œ๋„ hard-burned MgO๋Š” ๊ฐ•๋„ํ–ฅ์ƒ๊ณผ ๊ฑด์กฐ์ˆ˜์ถ• ์ €๊ฐ ํšจ๊ณผ๊ฐ€ ์žˆ๋Š” ๊ฒƒ์„ ์•Œ ์ˆ˜ ์žˆ์—ˆ๋‹ค. ๊ทธ๋Ÿฌ๋‚˜ OPC์™€ ๋‹ฌ๋ฆฌ ํ™œ์„ฑํ™”์ œ์˜ ์ข…๋ฅ˜์™€ ๋†๋„์— ๋”ฐ๋ฅธ MgO์˜ ํ™œ์„ฑํ™”์™€ ๋ฐ˜ ์‘ ์ƒ์„ฑ๋ฌผ์งˆ์˜ ์ฐจ์ด ๋“ฑ์„ ๊ณ ๋ คํ•  ํ•„์š”๊ฐ€ ์žˆ์„ ๊ฒƒ์œผ๋กœ ํŒ๋‹จ๋œ๋‹ค.

๊ฐ์‚ฌ์˜ ๊ธ€

์ด ๋…ผ๋ฌธ์€ 2014๋…„๋„ ์ •๋ถ€ (๋ฏธ๋ž˜์ฐฝ์กฐ๊ณผํ•™๋ถ€)์˜ ์žฌ์›์œผ๋กœ ํ•œ๊ตญ์—ฐ๊ตฌ์žฌ ๋‹จ์˜ ์ง€์›์„ ๋ฐ›์•„ ์ˆ˜ํ–‰๋œ ๊ธฐ์ดˆ์—ฐ๊ตฌ์‚ฌ์—… (NRF-2014R1A1A3052424) ์ด๋ฉฐ, ์ด์— ๊ฐ์‚ฌ๋“œ๋ฆฝ๋‹ˆ๋‹ค.

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