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1 Journal of the Korean Ceramic Society Vol. 47, No. 4, pp. 76~8, 010. DOI: /KCERS Adhesion Characteristic and Porosity Change of Alkali Silicate Impregnant of Concrete Hun Song, Yong Sik Chu, Jong Kyu Lee, and Young Chul Lim* Green Ceramics Division, Korea Institute of Ceramic Engineering & Technology, Seoul , Korea *Department of Architecture, Catholic University of Daegu, Gyeongsan 71-70, Korea (Received November 16, 009; Revised June 18, July ; Accepted July 15, 010) Silicate gj p we s p œ y z Á Á ³Á * w» * ƒm w w ( ; , 7 14 ; ) ABSTRACT There are the impregnating layer formation by surface protective materials or impregnants and the adhesion method by polymer, FRP sheet or steel plate in the surface protective method of concrete structure. The surface impregnation method by impregnants improves the durability of concrete structure by modifying the structure of the concrete surface and also have a merit that can be shortly applied in place without the decrease of concrete surface appearance and is easily applied again. This study is interested in manufacturing the concrete surface impregnants including lithium and potassium silicate for the repair of the exposed concrete and the color concrete requiring the advanced function in view of the concrete appearance. The durability and porosity properties was tested for the review of application. The result of this study show that the effective content of silicate ranges 5 to 0% and the separate application of the first impregnant and the second impregnant is effective for the optimum performance. The adhesion in tension is slightly increased but the reinforcement of concrete substrate is slight. So, the concrete impregnant of this study is more desirable for the improvement of durability rather than the reinforcement. Key words : Alkali silicate, Porosity change, Impregnant, Concrete, Durability 1. gj p td œ l y y ü w e. p œ w CO Cl w gj p ü ww. w gj p ü w t w gj p td l w ü en y. p, t ü»œ(open pore) mw y gj p yx ƒ w. w y w ü w 1,) ƒ t yœ œ. gj p t yœ t v ù we w wed x, s Corresponding author : Hun Song songhun@kicet.re.kr Tel : Fax : FRP pù q w. pù q w w. en we w t weœ gj p t l we w td» mw gj p ü w k. t weœ gj pt w š œ» œ ƒ w œ we we j z {w p. t weœ y, w, w, e gj p y w ù w zwš» ù y œ w w. 3-5) q en we Silane silicate w. Silicate en we gj p t ù ³ wew t l mm yd x w y CO Cl y e w w k y e œ w e y w. Fig. 1 lithium silicate 76

2 Silicate gj p we s p œ y 77 Table. Mix Proportions of Concrete Impregnants PL Type SiO content Liquid alkali silicate (wt%) Potassium silicate Lithium silicate Unit (wt%) Hardener (liquid wt%) Plain Fig. 1. Alkali silicate reaction mechanism of concrete impregnants. ) w en we p y Ca(OH) e f ùkü. Silicate we gj p en w w» w gj p Ca(OH) w» w y ƒw w gj p rw œw. w, mw e»» w» wš TiO y w w. en we»œ w g j p m» w š f gj p ƒ w. 6-8) Silicate we š v ü w alkali efflorescence lithium potassium silicate w e»» w gj p en we w š f gj p ƒ w mw. w w mw tw k y w w z en we s gj p td p œ y mw ü e w w mwš w.. x.1. gj p en we q lithium potassium silicate w š yw Table 1. Lithium potassium silicate gj p td en w w SiO w w š, y 0.15% ƒw gj p en we w. en we SiO w 5, 10, 0% wt Table... x en we p œ y d w» w k gj p x w. k gj p x KS F 403 gj p x œ w w. x ye 1 MPa m gj p. gj p x š, e 0 mm, yy š AE w. gj p w W/C 54.3% š, kg/m wt Table 3. w, t v 1 ±3cm, œ» 4±1% š gj p v œ» te w. p œ y q w» w k x w yw» w gj p w z 5mm w üš û p k w. k gj p x Table 1. Physical and Chemical Properties of Start Materials Color Silica content Li O content K O content Mole ratio Density (g/ml) Viscosity (cps at 0 o C) Lithium silicate water-white Potassium silicate water-white «4y(010)

3 78 zá Á ³Á Table 3. Mix Proportion of Plain Concrete W/C S/a Unit weight (kg/m 3 ) Water Cement Sand Gravel AE agent (C*%) Slump (cm) Air content Compressive strength (MPa) Concrete » z en we ù sw š 0.3 kg/m. 1 s 0. kg/m, s š 0.1 kg/m 1 s z 4 š sw. k x we t p, p œ y w š gj p x ü p w..3. x k x j» mm š en we s z fl w mm xp w d w. w, gj p we s wed p q w» w q x Fig. wš wed q xk 10 w s ƒw. q x we s z 1 3 w z d w. en we s œ p y d w» w w k x w we s z fl w 5mm w d w. œ œ d w s l(porosimeter) w d w. we s we¾ d 100 mm, 00 mm x gj p x w d w. zw we¾ d w» w k y x w z k y we sw w en¾ d w. we¾ d w 0 o C, 60%R.H., CO 10% k y w. 3. š 3.1. gj p en we gj p en we Fig. 3 ùkü. PL-5, 10 4cP ü w PL-10 ƒ w. PL-0 ƒ 10cP ù gj p we rw. en we e w ƒw ƒw w. lithium silicate ƒ potassium silicate» w. w ƒ ƒ w w š PL-5,10 PL-0 w w j ùkû. en we ƒ ¾ enw w» en w ü w ƒ. w ƒ gj p td e w œw we enƒ w. w e gj p k ww wš» ü w» w 1, en we sw w. p td œ ù w ³ wew» w. 3) Fig.. Adhesion test in tension and types of failure modes of specimens. w wz

4 Silicate gj p we s p œ y 79 Fig. 3. Temperature vs. viscosities of concrete impregnants. Fig. 4. Adhesion in tension to cement mortar substrates and failure mode distribution of concrete impregnants at curing periods of 1 and 3months. 3.. we p sƒ Fig. 4 en we s p k v q x ùküš. we s ƒw w 3.0 MPa z. m we s 1.0 MPa gj p k we gj p w» gj p ƒ j ùkû. en we PL-5 ƒ ùkþ we s ƒ w. w Plain x w 5% ü gj p y z w ùkû. Silicate en we gj p t w ed x w z ƒ û ü w w ww š q. we s ƒ ƒw w. p k x ƒ ƒw w. w, x q x 1 x q gj p xr td ƒ q xkƒ. td q we s w w ù we sw x td ƒ q Plain x ùkû. w, PL-5 ƒ td ƒ q xk ƒ ù kû PL-5 we ƒ ƒ ¾ enw gj p td w z. w p k xr ƒ jš ƒw» z w td q xkƒ ƒw w w. 3 xr q x w w ù td q xkƒ 1 xr w ƒw w œ s y en we sw x œ Table 4 ùkü. Plain x» ƒ 1 MPa m gj p œ 1.3 Vol%. en we sw PL-5, PL-10 PL-0 x œ ƒƒ 18.3, 17.1, 17.6 Vol% 3~4% w. y gj p œ œ (Gel pore), œ (Capillary voids), wœ (Air bubbles and voids)»œ(open pore) j w. œ Table 4. Porosity of Concrete Impregnants Plain PL-5 PL-10 PL-0 Porosity (Vol%) «4y(010)

5 80 zá Á ³Á Fig. 5. Porosity vs. pore size of concrete impregnants. ncao-sio -H O( w C-S-H y ) œ 1~5 nm j» gj p ƒ œ C-S-H y Ca(OH) œ 10 nm~1 µm j». w wœ 1µm j yy w w œ gj p w sw»s sww»œ gj p t d»œ w. gj p œ t l ü gj p œ w w e wš ü w w» w. en we gj p t l œ enw œ ü w w. 9) œ en we w w, p 100 µm œ ƒ x w. 100 µm œ AEyy w wœ»œ. w 100 µm œ en we sw x w w. gj p ü œ œ ù œ ƒw w ƒ j œ wœ ù»œ en we s w w q w. en we s gj p td w e œ w ü œ w w š, w gj p td»œ w s»œ xk wš w q w. en we s ƒ w š w» gj p ü enƒ w td wœ»œ œ j z {w. e n we s ƒ ƒ w œ ù w en¾ j z {w q. œ s œ Fig. 6 ùkü. œ 100 µm z œ yƒ x wš 100 µm j ƒw w ùkþ. œ y Fig. 7 ùkü. en we s gj p 0.05 µm œ ƒw w. w 1µm œ j w w 100 µm œ š œ l w w ü w dw. Fig. 8 FE-SEM Video Microscope w nm j» e d x»œ e gq y w. wœ ù w wz

6 Silicate계 콘크리트 함침제 도포에 따른 부착특성 및 공극변화 Fig. 9. Fig. 6. Carbonation depth of concrete impregnants. Cumulative porosity vs. pore size of concrete impregnants. Fig. 10. Fig Relative cumulative porosity change of concrete impregnants. Penetration depth of concrete impregnants. Plain 시험체의 경우 주경과 후 약 8 mm, 4주경과 후 약 10 mm, 8주경과 후 15 mm 정도의 CO 에 의한 탄산화 깊 이를 보였다. 침투성 함침제를 도포한 경우 Plain 시험체 보다 탄산화의 진행이 적어 함침제 도포에 따른 효과를 확인할 수 있었다. 이는 침투성 함침제가 콘크리트 내부 의 Ca(OH) 와 반응하여 CaSiO 의 결정층을 생성하여 구 체강화 및 열화방지의 효과를 발휘한 것으로 판단된다. 촉진 탄산화시험 후의 침투성 도포제의 도포에 따른 침 투깊이를 Fig. 10에 나타내었다. 실리카 함량이 5%로 점 도가 작은 PL-5 시험체의 경우 약 5 mm 정도로 침투깊 이는 가장 크게 나타났다. PL-10 및 PL-0 콘크리트 함 침제를 도포한 시험체의 경우 4 mm, 1 mm 전후로 나타 나 실리카 함량이 높을수록 침투깊이는 작게 나타났다. Silicate계 침투성 함침제는 약 ph가 13인 강알칼리 용 액으로 기 탄산화된 부분에 침투하여 알칼리 부여와 성 능회복에 유효할 것으로 판단된다. 침투성을 향상을 위해 실리카 함량 및 점도를 조절하며 반응촉진제나 경화제를 첨가하여 사용한다. Sodium silicate는 습윤바탕에 적용하 는 것이 일반적이며 lithium 및 potassium silicate는 건조 Fig. 8. SiO Coated in concrete surface structure with PL. 린 기공은 100 um ~1 mm의 크기이므로 침투성 함침제의 도포에 따라 내부로 침투하여 공극의 일부가 메워지는 효 과를 발휘할 수 있다. 또한 내부로 침투된 함침제는 CaSiO 의 결정층을 생성하여 CO 나 Cl 침입을 차단하여 구조물의 내구성을 향상시킨다. 탄산화 및 재알칼리화 침투깊이 시험체의 촉진 탄산화시험 결과를 Fig. 9에 나타내었다. 촉진 탄산화시험 결과 침투성 함침제를 사용하지 않은 제 47 권 제 4호(010)

7 8 zá Á ³Á Fig. 11. Alkali recovery depth of concrete impregnants. k sw w. gj p rw œw š»œ w gj p m» w. 3,5) w en¾ ù ù kü» w 1, s w 1 s en s kwš s g j p»œ w w v w. z en¾ y z ù e z w x s w ƒ v w. 4. Silicate gj p en we s gj p td p œ p yw ü wƒ y w w. 1. Silicate en we SiO w š ƒ û PL-5ƒ en¾ d ƒ w š PL- 0 k y d ƒ w. gj p en y w zw e w 5~10% {w» w 1, s we w w zw.. we s ƒw w ù we s x w y z {w w. w q xk td ƒ q xkƒ ƒw w t d y w ù x w z» w». Silicate gj p en we k y ü w w w. 3. we s œ w œ»œ 100 µm yƒ j ùkû gj p td l ü en w td œ 3~4% w. 4. Silicate gj p en we gj p td œ g k y ü w z ƒ j. w œ w wš»œ xk w» z ƒ en¾ z y w w w w ƒ v w. REFERENCES 1. H, Song, Y. S. Chu, and J. K. Lee, Carbonation and Cl - Penetration Resistance of Alkali Silicate Impregnant of Concrete(in Korean), J. Kor. Ceram. Soc., 45 [11] (008).. KICET, Developmet of Self Cleaning Surface Protect Concrete Impregnant(in Korean); pp , KICET, JSCE, Recommendation for Concrete Repair and Surface Protection of Concrete Structures(in jpn); pp. 10-9, Jpn. Soc. Civil Eng., AIJ, Japanese Architectural Standard Specification(in jpn); JASS 18 Paint Work, pp , Archi. Insti. Jpn., AIJ, Test Methods for Quality Control and Maintenance of Reinforced Concrete Buildings(in jpn); pp , Archi. Insti. Jpn., JCI, Repair Methods of Concrete Structures(in jpn); Committee Report, pp. 1-8, Jpn. Conc. Insti., K. K. Kim, M. S. Paik, I. M. Song, Y. D. Lee, and S. J. Jung, Performance Evaluation of Concrete Surface Painted on Types Silicic Lithium(in Korean), J. Archi. Insti. Kor., 3 [11] (007). 8. S. K. Oh, S. D. Ahn, and S. M. Shim, Effect of Silane Solution of Capillary Coating Type as Protection Agent of Absorption for the Durability Improvement in Concrete Surface Layer(in Korean), J. Archi. Insti. Kor., 17 [1] (001). 9. P. Kumar Mehta, Paulo J. M. Moteiro, Concrete Microstructure, Properties, and Materials; pp McGraw Hill, New York, 006. w wz