AC Impedance Characteristics of Ternary Cementitious Materials

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1 JOURNAL OF THE CHINESE CERAMIC SOCIETY 1059 Vol. 40 No. 7 July ( ) 50% 65% 1 TQ172 A (2012) :54:47 AC Impedance Characteristics of Ternary Cementitious Materials AN Xiaopeng 1 SHI Caijun 1 HE Fuqiang 2 WANG Dehui 1 (1. Department of Civil Engineering, Hunan University, Changsha , China; 2. Department of Civil Engineering and Architecture, Xiameng University of Technology, Xiameng , Fujian, China) Abstract: During the operation of subway, stray current has negtive effects on the durability of concrete. In the preparation of concrete, use of fly ash and slag to replace some cement can increase the resistance of concrete and corrosion resistance of steel in the concrete. This study investigated the impedance characteristics of ternary cementitious materials and obtained the electrical resistance contours of the materials at different ages. It was found that when total content of fly ash and slag powder was in the range of 50% 65% and fly ash to slag content ration was around 1, mortars made with the ternary cementitious material demonstrated the highest resistance. Key words: ternary cementitious materials; triangle coordinate; resistance; alternating current impedance [1 2] Ω m [3] [4] [5] (2009CB623103) ( ) ( ) (1988 ) (1963 ) Received date: Revised date: First author: AN Xiaopeng (1988 ), male, Master candidate. Correspondent author: SHI Caijun (1963 ), male, Ph.D., Professor. caijunshi@yahoo.com

2 [6 7] SHI [8] [5] [9 10] R 0 R 1 OH [9] S Table 1 1 Chemical component of the cement w/% Material SiO 2 Al 2 O 3 Fe 2 O 3 CaO MgO SO 3 K 2 O f-cao Iginition loss Cement Fly ash Slag Table 2 Physical property of fly ash Residue on 45 μm sieve/% Water requirement/% Moisture content/% Activity index at 28 d/% Table 3 Physical property of slag Density/(kg m 3 ) Specific surface area/(m 2 kg 1 ) Moisture content/% Activity index at 28 d/% : mm 40 mm 160 mm 1 d (20 ± 2) d 28 d 56 d 2 IviumStat 0.01 Hz 1 MHz 7 2

3 [5] Fig. 3 Illustration of microstructure of concrete [5] DP Discontinunous point; DCP Discontinunous conductive path. ICP Isulature conductive path; CCP Continounous conductive path. 1 Fig. 1 Composition of ternary cementitious materials Table 4 Sample No. 4 Composition of cementitious materials Mass fraction/% Cement Fly Ash Slag ( ) [11 12] [5,7,11,13] 4 R 0 R 1 R 0 R 1 [5,11] 2 Fig. 2 Illustration of apparatus for impedance measurement Song [5] DCP ICP CCP R CP R CCP ( 3) DCP ICP CCP 4 Fig. 4 Typical AC impedance spectra of portland cement pastes Song [5] RCP = ( R0 + R1 ) R0 R1 (1) RCCP = R0 + R1 RCP RCCP = R0 R1 C = C [ R /( R + R )] DP (2) (3) (4) R CP 3 ICP DCP R CCP

4 CCP R 0 R 1 C DP C 1 (R 0 +R 1 ) (2) R CCP R 0 R 1 (1) (R 0 +R 1 ) (R 0 /R 1 ) R CP (3) R CP R CCP Fig. 5 5 AC impedance spectra of cement mortar at different ages C DP [5] 0<R 0 <<R 1 <1 (4)C DP C 1 Ca 2+ Na + K + OH SO 2 4 Ca 2+ SO 2 4 [8] Na + K + OH [7 8] (C S H) (C/S) C/S d 56 d [5] [5] C 1 5 ( ) d 2 3 R 0 R 1 R CCP R CP (1) R CP R 0 /R 1 5 R 0 /R 1 Song d Fig. 6 AC impedance spectra of mortar specimens No.2 and No.3 at 7 d

5 [5] C S H 6 3 R 1 2 R 0 R 1 R 0 2 R 0 3 [11,13 14] R [15 17] 1 d d (R 0 +R 1 ) (R 0 +R 1 ) 6 2 (R 0 +R 1 ) Ω Ω 2 3 [18 19] 7 d 5% 7 d 35% [20] 6 [21] d d ( R 0 ) Song [5] 3 7 d 2 3 (R 0 /R 1 ) [22] d Fig. 7 AC impedance spectra of mortar specimen No.2 and No.3 at 56 d ( R 0 ) R 0 /R 1 (R 0 +R 1 ) [19] 7 d 3 5 OH OH 2 [8,18 19] 7 56 d 2 3 3(R 0 +R 1 ) [18 19] 28 d d 56 d ( C 1 ) Ω (4) C DP d 3 70% 6 (R 0 +R 1 )

6 d Fig. 8 AC impedance spectra of mortar specimen No.2, No.3 and No.6 at 56 d d Kriking 7 d 9 9 [8,15] 9 C S H C S H 9 7 d Fig. 9 Electrical resistance contours of mortar at 7 d [23] [7] 9 50% d 28 d d Fig. 10 Electrical resistance contours of mortar specimens at 28 d

7 d 7 d 28 d d d d d 1:1 ( ) d Fig. 11 Electrical resistance contours of mortar specimens at 56d [24] 11 35% ( ) OH [25] ph [8] 50% 65% 56 d ) R 0 R 1 56 d 2) 28 d 56 d 3) 50% 65% 1:1 56 d 2.5 [1],. [J]. ( ), 1999, 11(6): ZHOU Xiaojun, GAO Bo. West-china Explor Eng & Soil Drill Tunnel, 1999, 11(6): [2] SHI C, HU S. Cementitious properties of ladle slag fines under autoclave curing conditions [J]. Cem Concr Res, 2003, 33: [3],,. [J]., 2009(1): ZHONG Yongxiang, LENG Faguang, et al. China Build Mater Sci Technol (in Chinese), 2009(1): [4] MELAND I. Influence of condensed silica fume and fly ash on the heat evolution in cement pastes [C]// Proceeding CANMET/ACI 1st Internatimal Conference on the Use of Fly Ash, Slag and Other Mineral

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