Effects of mixture composition and time on dielectric constant of fresh concrete

by 1979- Leon, Cesar Octavio

LEON, CESAR OCTAVIO. Effects of Mixture Composition and Time on Dielectric Constant of Fresh Concrete. (Under the direction of Dr. Michael L. Leming). The strength and durability properties of concrete are related to its water cement ratio. Previous studies have shown that electrical properties of concrete appear to be related to both the water and cement contents of a mixture as well. In this study, a new technique and device were developed to measure the apparent dielectric constant of a concrete mixture at early stages of hydration. The ability of the device to be used as a tool for fundamental understanding of dielectric properties of fresh concrete and its potential to be used as field testing for quality control during early stage of concrete were analyzed. Differences on the apparent dielectric constant measurements due to external variables such as time and frequency were studied. Analysis was made for variations of the apparent dielectric constant due to changes in the mixtures components such as water, cement and fly ash contents. The effects on the apparent dielectric constant due to inclusion of water reducing admixture were also analyzed. The relationship between apparent dielectric constant and the compressive strength of the concrete was of special interest for this study. The method was found to be potentially useful in identifying changes which would cause differences in compressive strength among similar mixtures. The analysis showed a limitation for using the apparent dielectric constant alone in order to identify between any given mixtures.