The dielectric permittivity of cementitious
materials during 24 hours hydration period at a frequency of 2.45 GHz using a
network analyzer with open-ended probe technique was measured. Influences of
water-to-cementitious ratios, cement types, pozzolans and aggregate types are
taken into consideration. The results show that dielectric permittivity is
strongly affected by initial water-to-cementitious ratio and the rate of
hydration reaction which can be changed by fineness of cement (Types 1 and 3),
pozzolan materials and aggregates (river sand with/without crushed limestone
rock). Dielectric permittivity is relatively high and remains constant during
the dormant period, after that it decreases rapidly when the hydration reaction
resumes and continues to decrease during the acceleratory period.
K. Y. C. Leung and T. Pheeraphan, “Microwave Curing of Portland Cement Concrete: Experimental Results and Feasibility for Practical Applications,” Construction and Building Materials, Vol. 9, No. 2, 1995, pp. 67-73.
http://dx.doi.org/10.1016/0950-0618(94)00001-I
R. G. Hutchinson, et al., “Thermal Acceleration of Portland Cement Mortars with Microwave Energy,” Cement and Concrete Research, Vol. 21, No. 5, 1991, pp. 795- 799. http://dx.doi.org/10.1016/0008-8846(91)90174-G
F. H. Wittmann and F. Schlude, “Microwave Absorption of Hardened Cement Paste,” Cement and Concrete Research, Vol. 5, No. 1, 1975, pp. 63-71.
http://dx.doi.org/10.1016/0008-8846(75)90108-8
S. Wen and D. D. L. Chung, “Effect of Admixtures on the Dielectric Constant of Cement Paste,” Cement and Concrete Research, Vol. 31, No. 4, 2001, pp. 673-677.
http://dx.doi.org/10.1016/S0008-8846(01)00475-6
H. C. Rhim and O. Buyukozturk, “Electromagnetic Properties of Concrete at Microwave Frequency Range,” ACI Materials Journal, Vol. 95, No. 3, 1998, pp. 262-271.
