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1 Journal of the Korean Ceramic Society Vol. 44, No. 9, pp. 489~495, Physical Properties of Ultrafine Ash Blended Cement Dong-Woo Yoo, Seung-Ho Byun, and Jong-Taek Song Department of New Materials Science and Engineering, Dankook University, Cheonan , Korea (Received August 14, 2007; Accepted September 14, 2007) yww p Á yá k w œw ( ; ) ABSTRACT Effects of ultrafinely ground ash on the rheological properties of cement paste were investigated. Also compressive strength development and setting time of ultrafine ash blended cement mortar were investigated in the study. A sample with silica fume was included for comparison. According to the results of ultrafine ash blended cement paste in the lower W/B ratio, the fluidity were high, and the setting time was a little retarded. And the compressive strength of ultrafine ash blended mortar was increased in the long term. In the case of hardened cement paste at 28 days, Ca(OH) 2 contents was decreased in order of control, ultrafine ash, silica fume blended cement due to difference of the pozzolanic reaction. Key words : Rheology, Grinding ash, Blended Cement 1. m gj p xy,» yƒ ƒ š, š gj p ƒ ƒwš. š gj p t w j» w ƒ p yw w ƒ w š, t v, š, e v. 1-4) p š gj p p yw p yƒ ùkùš, yw p gj p w ¾. š gj p ƒ w w ù š ƒ. yw v y, ü y ƒ w y š. kz(ash, z) y k z ƒ wì,» w z w. w gj p yw š v (fly ash) š, w z(reject Corresponding author : Jong-Taek Song Song8253@dankook.ac.kr Tel : Fax : ash) w. v m p yw wš ù, z s» wš» y q wš. v š p ƒ z ƒœw, š ev t ƒ š w. w p yw w z š w. 2. x 2.1. x p S m sp p ( w OPC w) w, yw S š ( w BFS w) w. v w y ( w FA w) w š, ev E t( w SF w) w., z 14,000 cm /g ( w UFA 2 w) w w. ƒ yw Table 1 ùkü. š ü W s e š y ( w, PC w) w. w, XRD vj Fig. 1 ùkü. SF w, w vj ùkü s y y 489

2 유동우 변승호 송종택 490 Table 1. Chemical Compositions of Raw Materials OPC BFS FA SF UFA Reject ash Al2O SiO Fe2O CaO MgO K2O Na2O SO (wt %) Ig.loss Average particle Size (µm) Fig. 2. Particle size distribution of ultrafine ash and reject ash. Fig. 1. XRD patterns of raw materials. Table 2. Mixing Ratio of Raw Materials System OPC OPC-SF OPC-UFA BL Blended cement BL-SF (BL system) BL-UFA OPC :ordinary portland FA :fly ash, SF :silica fume, BL :blended cement. OPC system OPC BFS FA cement, BFS :blast UFA :ultra fine ash, (wt %) SF UFA furnace slag, 성이 높을 것으로 예상되었고, BFS, FA, UFA 모두 SF에 비하여 낮은 할로우 피크를 나타내었다. 이때 사용한 XRD 는 Rigaku사의 DMax-2200H이다. 본 실험에서 혼합재의 사용을 OPC 단순계와 OPC+BFS +FA의 복합계에서 각각 SF와 UFA를 OPC에 치환 적용 하여 실험하였고, 혼합재의 치환 배합을 Table 2에 나타 한국세라믹학회지 Fig. 3. SEM photographs of reject ash(a) and ultrafine ash(b). 내었다. 각각의 시멘트 페이스트 실험을 위하여 W/B=50%, 및 60%에서 실시하였으며, 특히 W/B=24%에서는 복합계에 SP(B 1.8%)를 적용하여 실험을 실시하였다. 분쇄 애시의 성상 원료 잔사회와 분쇄 후 14,000 cm /g 블레인 값을 나타 내는 애시의 입도 분포를 Fig. 2에 나타내었다. Fig. 3은 이들 시료의 입자형태를 전자현미경(SEM)으로 관찰한 것이다. UFA(b)는 잔사회(a)에서 보이는 다공질체 는 나타나지 않았으며, 비교적 둥근 형태의 입자 형상을 나타내었다. 이는 다공질성의 입자가 외력에 대한 분쇄정

3 yww p 491 w w w ph meter(hanna ph211) w x ww. y» l 30 ¾ 5, z 20 d w. ƒ p k p» w W/B 0.45, 0.40, 0.24 x w, 20 C» w o data logger(kyowa UCAM- 209C) w 24~40 y w. w» ü (0 0 Fig. 4. Relative compressive strength of cement mortars for the samples containing different replace ratio of UFA. ƒ», e,, w». z XRF(Rigaku, ZSX Primus II) w w, z z j w. XRF Table 1 ùkü. 14,000 cm /g w 2 k d w, OPC 0% w Fig. 4 ùkü. 8,000 cm /g %¾ ƒ ƒw šƒ ù, 5) x % ey OPC w ùkü š, 28 20% ¾ w, 56 40% ey¾ ùkü. p 20% ey % ùkü p x p r p p q w» w, r p v d w š, z w y d z, y ùkü l š d w q w. p r p v x v g ü 38.1 mm, 19 mm, 57.2 mm w. l š 7) w ƒ w mx» š z (1/s) 0rpm š 200 rpm ¾ ƒ 200 w g d w. x z HAKKE Rheostress 600, spindle Z40DIN w yp x ƒ p phƒ e w» Fig. 5. Change of mini-slump with time in cement pastes. (a) OPC system (W/B = 50%, 60%), (b) BL system (W/B = 50%, 60%), and (c) BL system (W/B = 24%, SP = 1.8%) 44«9y(2007)

4 492 Á yá k 0) mm 3 š, j»ƒ 3 ( ) mm» w w. t (KS L 50) w š, y w y d w» w B:S=1:1 w. y p r p r p»œ 3, 7, 28 w š, DCS w Ca(OH) 2 28 w.»œ d mercury porosimeter(micromeritics Auto Pore 9420) w p k d p k š w w W/B =24% SP B 1.8% w š, p k š y w ³ 5y ( 2.82) 4y ( 3.03) ƒƒ 50% w, B:S=1.06:1 xw. 3. š 3.1. p ƒƒ p r p v d Fig. 5 ùkü. v x ww W/Bƒ š SP w OPC ù BL w ƒ ùkü š, d OPC(BL)>UFA>SF ùkû. W/B OPC w BFS FA sww w j ùkù. ù û W/B (24%) SP 1.8% BL-UFAƒ BL-SF ùkû, d BL- UFA>BL >BL-SF ùkû. SFƒ p r pù gj p w jš, š š š ew. w x SFƒ 2,6,8)» SP d w d Fig. 6. Change of hysteresis loop area with time in cement pastes of OPC system. x w w. SF p t sww w SP w š, ƒ ƒ w. ù x 6,) š SF š ƒ š. x 9) û W/B š w, SF e y w ùkü, UFA ey w y ùkü. z w l š Figs. 6 7 ùkü. l š Pa/s w, z ƒ w š w. w w» ùkü ƒ. w, l š d p r p q mw š. 7) x d w l š W/Bƒ j ùkü š, SF>UFA>OPC(BL) ùkû, SPƒ W/Bƒ û BL-SF BL-UFAƒ j ùkü. p r p z Fig. 7. Change of hysteresis loop area with time in cement pastes of BL system. w wz

5 yww p 493 Fig. 8. Change of ph value with time in cement slurries of BL system. Fig. 9. Heat evolution rate with time in cement mortars of BL system. (W/B = 24%, SP = 1.8%) ƒw BL-SF w BL-UFA ƒ w» ùkû. w W/B û W/B j ƒ ùkû, û W/B û w r p š» w ùk ù y w w ùkü. w p. 3.2 y p x p r p» yw z p y Ca(OH) 2 y w» w, BL w w p r p ph x w 90 ü ph y BL >BL-UFA >BL-SF ùkû, SF ƒw Ca(OH) 2 ƒ. SF t Ca(OH) 2 w wƒ ùkù f pƒ t w d x Ca(OH) 2 w» ƒ. ) yw y p w y w» w p k y d w. BL-SF BL w w w š, BL-UFA w w ùkû. Fig. 9 ù kü. w SF Ca(OH) 2 w w C 3 S y w, UFA C 3 S y j, ƒ yvj w w š š, 11,12) x w ùkü. p SF C 3 S y y w w C 3 S» w, C 3 S y Ca(OH) 2 y y SF w Ca(OH) 2 w j. SF yvj» w w, w w šƒ. ) š w p r p y z e s y mw» w SP w û W/B (24%) w ƒƒ y w»œ d w š, p 28 DSC w Ca(OH) 2 w.»œ Fig. ùkù 3 BL-UFA>BL>BL-SF ùkû ù, 7 BL- UFA>BL-SF>BL ë, 28 BL>BL-SF>BL-UFA ë. ù, BL-SF BL»œ w ùkü 3 w sw BFS ƒ, UFA ey w ƒ»»œ ùkü ƒw»œ ww p» s» w ƒ. UFA yw C 3 S» s. OPC SP w W/B =24 p r p w d w,» 3 w w û»œ ùkü ù, 7»œ ùküš, 28»œ ùkü Fig.. Total pore volume of cement pasts of BL system with respect to curing time. (W/B = 24, SP = 1.8%) 44«9y(2007)

6 494 Á yá k Fig. 11. Ca(OH) 2 content in the hardened cement pastes measured by DSC. Fig. 12. Compressive strength of cement mortars at BL system.. w x w sw BFS FA s w e ¼ w» w» ƒ. 28 Ca(OH) 2 Fig. 11 ùkü. Ca(OH) 2 OPC>BL >BL-UFA>BL-SF ùkû, BL-UFA BL-SFƒ s y ùk ûš, XRD w vj ew. DSC d 170 o C vjƒ ùkù, r p w ƒ š, OPC w j vj ùkü. w w ƒ ey» SO 3» w p k p k š ( 80 MPa) xp» w SP wš W/B =24% B:S=1.06:1 w xw. xp Fig. 12 ùkü. BL-UFA 3 û p ùkü, 14 z x p ùkü, BL-SF BL w 14 ¾ û ù kü ƒ 28 ww ùkü. w p r p»œ d w w š. 4. yww p w x w. (1) p r p p x W/B(50 ~ 60%) ƒ UFA ƒ w ù, SPƒ š û W/B(24%) v, l š w p ùkü. (2) p x UFA p yvj j w ƒ, x SF w x w ùkû. (3) p r p»œ d UFA»»œ,» û»œ,» p r p e yƒ y w. (4) 28 DSC w Ca(OH) 2 Ca(OH) 2 BL >UFA > SF ùkù UFA, SF s y ùkþ, SFƒ ƒ û Ca(OH) 2 w. (5) p k UFA» û ùkü ù, 28 ƒ ùkü, p r p»œ w ùkü., z ƒœw UFA š p yw w ƒ q, w x z w w q. REFERENCE 1. J. T. Song, C. D. Yoo, and S. H. Byun, Effect of Blastfurnace Slag Fineness on the Rheological Properties of Cement PastesOin Korean), J. Kor. Ceram. Soc., 44 [2] 3-09 (2007). 2. M. Nehdi, S. Mindess, and P. C. Aitcin, Rheology of highperformance concrete : effect of ultrafine particles, Cem. Concr. Res., 28 [5] (1998). 3. Chiara F. Ferraris, Karthik H. Obla, and Russell Hill, The Influence of Mineral Admixtures on the Rheology of Cement Paste and Concrete, Cem. Concr. Res., (2001). 4. H. J. Hwang, S. H. Lee, and W. J. Lee, Effect of Particle w wz

7 yww p 495 Size Distribution of Binder on the Rheological Properties of Slag Cement PastesOin Korean), J. Kor. Ceram. Soc., 44 [1] 6-11 (2007). 5. J. H. Kim, S. M. Kim, H. C. Sik, and J. D. Jang, A Study on Strength of Cement Mortar with Micro Grinding High- Volume Fly-ash, J. AIK, 15 [3] 81-8 (1999). 6. C. K. Park, M. H. Noh, and T. H. Park, Rheological Properties of Cementitious Materials Containing Mineral Admixtures, Cem. Concr. Res., (2005). 7. David A. Williams, Aaron W. Saak, and Hamlin M. Jennings, The Influence of Mixing on the Rheology of Fresh Cement Paste, Cem. Concr. Res., 29 [2] (1999). 8. P.F.G. BANFILL, Rheology of Fresh Cement and Concrete, E.&F.N.SPON, (1991). 9. Committee report on fluidity of cement concrete, Japan cement association, (2003).. CEMENT & CONCRETE Encyclopedia, Japan cement association, 4-06 (1996). 11. Wei Fajun, Michael W. Grutzeck, and Della M. Roy, The Retarding Effects of Fly Ash Upon The Hydration of Cement Pastes : The First 24 Hours, Cem. Concr. Res., 15 [1] (1985). 12. Y. Halse, P. L. Pratt, J. A. Dalziel, and W. A. Gutteridge, Development of Microstructure and other Properties in Flyash OPC Systems, Cem. Concr. Res., 14 [4] (1984). 44«9y(2007)