40 7 40 7 2012 7 JOURNAL OF THE CHINESE CERAMIC SOCIETY 1059 Vol. 40 No. 7 July 2012 1 1 2 1 (1. 410082 2. 361024) 50% 65% 1 TQ172 A 0454 5648(2012)07 1059 08 2012 07 03 14:54:47 http://www.cnki.net/kcms/detail/11.2310.tq.20120703.1454.201207.1059_024.html 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 410082, China; 2. Department of Civil Engineering and Architecture, Xiameng University of Technology, Xiameng 361024, 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] 10 4 10 9 Ω m [3] [4] [5] 2012 01 17 2012 03 20 973 (2009CB623103) (5097 8093) (51072050) (1988 ) (1963 ) Received date: 2012 01 17. Revised date: 2012 03 20. First author: AN Xiaopeng (1988 ), male, Master candidate. Correspondent author: SHI Caijun (1963 ), male, Ph.D., Professor. E-mail: caijunshi@yahoo.com
1060 2012 [6 7] SHI [8] [5] [9 10] R 0 R 1 OH [9] 7 1 1.1 S95 1 3 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 21.09 4.34 2.81 62.50 1.81 2.87 0.62 0.67 2.65 Fly ash 54.29 22.55 5.53 1.34 1.08 0.29 1.49 2.24 5.92 Slag 33.60 15.73 1.03 38.35 9.96 0.12 0.51 0.94 0.36 2 Table 2 Physical property of fly ash Residue on 45 μm sieve/% Water requirement/% Moisture content/% Activity index at 28 d/% 6.2 90 0.2 67 3 Table 3 Physical property of slag Density/(kg m 3 ) Specific surface area/(m 2 kg 1 ) Moisture content/% Activity index at 28 d/% 2 900 413 0.1 110 1.2 1 4 1.3 4 0.38 1:3 0.38 40 mm 40 mm 160 mm 1 d (20 ± 2) 1.4 7 d 28 d 56 d 2 IviumStat 0.01 Hz 1 MHz 7 2
40 7 1061 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 1 100 0 0 2 30 70 0 3 30 0 70 4 65 35 0 5 65 0 35 6 30 35 35 7 53 23.5 23.5 4 ( ) [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] 3 3 4 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 1 1 0 1 2 (2) (3) (4) R CP 3 ICP DCP R CCP
1062 2012 3 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] 3 3.1 (C S H) (C/S) C/S 5 3 7 28 d 56 d [5] [5] C 1 5 ( ) 5 3.2 2 3 6 6 7 d 2 3 R 0 R 1 R CCP R CP (1) R CP R 0 /R 1 5 R 0 /R 1 Song 6 2 3 7 d Fig. 6 AC impedance spectra of mortar specimens No.2 and No.3 at 7 d
40 7 1063 6 2 [5] C S H 6 3 R 1 2 R 0 R 1 R 0 2 R 0 3 [11,13 14] R 0 2 3 [15 17] 1 d 28 120 d (R 0 +R 1 ) (R 0 +R 1 ) 6 2 (R 0 +R 1 ) 2 500 Ω 3 6 500 Ω 2 3 [18 19] 7 d 5% 7 d 35% [20] 6 [21] 7 2 3 56 d 7 6 3 7 d ( R 0 ) Song [5] 3 7 d 2 3 (R 0 /R 1 ) [22] 2 7 2 3 56 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 ) 2 2 6 3 2 3 [18 19] 28 d 6 7 2 7 d 56 d ( C 1 ) 600 700 Ω (4) C DP 3 8 2 3 6 56 d 3 70% 6 (R 0 +R 1 )
1064 2012 8 2 3 6 56 d Fig. 8 AC impedance spectra of mortar specimen No.2, No.3 and No.6 at 56 d 2 3 3.3 3.3.1 7 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% 9 3.3.2 28 d 28 d 10 10 10 28 d Fig. 10 Electrical resistance contours of mortar specimens at 28 d
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