Use of Dielectric Constant for Determination of Water-to-Cement Ratio (W/C) in Plastic Concrete: Part 1. Volumetric Water Content Modeling
Abstract
This paper series includes two parts: (1) volumetric water content modeling, and (2) comparison determined w/c values by ground penetrations radar (GPR) and microwave oven drying measurements. In part (1), the several empirical equations and theoretical models for determining volumetric water content of plastic concrete by dielectric constant value were reviewed. The applicability of these models in determining volumetric water content of plastic concrete was statistically evaluated by the experimental data in literature. It was found that the logarithmic rule proposed by Lichtenecker for plastic concrete’s volumetric water content calculation from its constituents’ volumetric fractions and dielectric constant values provides the most accurate volumetric water content determination results when compared with other models discussed in this work. The p-value of the t-test of difference between the calculated volumetric water contents and the determined volumetric water contents for the logarithmic rule was 0.07341, the mean value and variance value of t-test of difference results from the logarithmic rule was -0.29% and 0.98, respectively. The investigation results from this work indicate that dielectric constant value of concrete might be used as an indicator of water content of freshly mixed concrete, which will be further used to calculate the water to cement ratio of concrete in part 2 of this work.