Cement Paste Compressive Strength Estimation using Nondestructive Microwave Reflectometry
Microwave reflection properties of four cement paste samples with various water-cement (w/c) ratios were measured daily for 28 days using microwave frequencies of 5, 9, and 13 GHz. The dielectric properties of these samples, and hence their reflection coefficients, were measured daily and shown to decrease as a function of increasing w/c ratio. This is as a direct result of curing (no chemical interaction or hydration). The presence of curing as indicated by this result indicates that microwaves could be used to monitor the amount of curing in a concrete member. The variation in the reflection coefficient of these samples as a function of w/c ratio followed a trend similar to the variation of compressive strength as a function of w/c ratio. Subsequently, a correlation between the measured compressive strength and reflection coefficient of these blocks was obtained. The early results indicated that lower frequencies are more sensitive to compressive strength variations. However, further investigations showed that there may be a frequency around 5 GHz which is the optimum measurement frequency. This result can be used to directly and nondestructively estimate the compressive strength of a cement paste and mortar blocks.
R. Zoughi et al., "Cement Paste Compressive Strength Estimation using Nondestructive Microwave Reflectometry," Proceedings of Advanced Microwave and Millimeter-Wave Detectors (1994: San Diego, CA), vol. 2275, pp. 89-93, SPIE--The International Society for Optical Engineering, Jul 1994.
The definitive version is available at http://dx.doi.org/10.1117/12.186705
Advanced Microwave and Millimeter-Wave Detectors (1994: Jul. 25-26, San Diego, CA)
Electrical and Computer Engineering
Keywords and Phrases
Cements; Compression Testing; Concrete Construction; Curing; Dielectric Properties; Electromagnetic Wave Reflection; Estimation; Monitoring; Mortar; Nondestructive Examination; Optimization; Cement Pastes; Microwave Reflectometry; Microwave Devices
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