Determining Water Content of Fresh Concrete by Microwave Reflection Or Transmission Measurement


Book Description

In search of a rapid and accurate method for determining the water content of fresh concrete mixes, the microwave reflection and transmission properties of fresh concrete mixes were studied to determine the extent of correlation between each of these properties and water content. This report describes the procedures that were devised to measure these properties and the results that were obtained. The results indicated that the microwave reflectivity and transmission of fresh concrete mixes are both sufficiently correlated to water content. Since these properties can be measured very rapidly without any pretreatment of the fresh concrete samples, microwave reflectivity or transmission measurement has the potential to be a rapid, nondestructive, and reasonably accurate quality-assurance method for measuring the water content of fresh concrete mixes, especially for a large capacity ready-mix plant. Although it is slightly more elaborate than reflectivity measurement, it is believed that transmission measurement may yield a more precise and accurate method.




Handbook on Nondestructive Testing of Concrete


Book Description

Civil engineers will value this resource that examines the tools and techniques used to estimate the in-place strength on concrete, permeation properties that relate to potential durability, and the methods used to assess the internal condition of concrete and the corrosion activity of steel reinforcement.




Pavement Management Implementation


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Determination of Water Content of Fresh Concrete Using a Microwave Oven


Book Description

As part of the Strategic Highway Research Program (SHRP) contract, Optimization of Highway Concrete Technology, a microwave-oven method for measuring water content of as-delivered fresh concrete was evaluated. Water contents of a series of concrete mixes prepared in the laboratory were gravimetrically determined by drying the concrete in a microwave oven and comparing these measurements with water contents used for making these mixes. A relatively high-power microwave (900 W) equipped with a turntable to provide uniform drying was used. Mixes used in the study included conventional concrete mixes with three types of aggregates with low, moderate, and high water absorptions and mixes with silica fume, fly ash and latex. Field ruggedness of the procedure was verified by testing under actual field conditions at placements of bridge deck overlays and full-depth pavement repair sections.




Development of a Water-Cement Ratio Meter


Book Description

The objective of this project was to develop a water-cement ratio measurement meter for easy, rapid and reliable use in the field. The goal was that the equipment be portable, easy to use, low cost and low maintenance, and be able to provide consistent and accurate results. A prototype device has been developed to measure the water-cement ratio of a plastic concrete mix. The method is based on the turbidity of water-cement slurry separated from a concrete mixture by "pressure sieving". Consistent results were obtained for both air entrained and non-air entrained concrete. Statistical analyses of the test results have shown that the Kansas Water-Cement Ratio Meter can measure the water-cement ratio of fresh concrete with an accuracy of +/-0.01 with 90% confidence. The test time is less than 10 minutes which includes cleaning the equipment. Further evaluation with admixtures, and under field conditions are planned




Testing and Validation of the Kansas Water-cement Ratio-meter


Book Description

A prototype device, the Kansas Water-Cement Ratio Meter, has been developed that can measure the water-cement ratio of a plastic concrete mix. The method was based on the measurement of the turbidity of the water-cement slurry separated out of a concrete mixture by pressure sieving. This study was undertaken to improve the meter and to do a sensitivity analysis.







Ground Penetrating Radar for Evaluating Subsurface Conditions for Transportation Facilities


Book Description

This synthesis will be of interest to state Department of Transportation (DOT) geotechnical, bridge, and pavement engineers, engineering geologists, consultants involved with ground penetrating radar (GPR) investigations for state DOTs, and researchers. It describes the current state of the practice of using GPR for evaluating subsurface conditions for transportation facilities. This was accomplished by conducting a literature search and review and an extensive survey of U.S. and Canadian transportation agencies and practitioners, as well as limited international information collection. GPR is a noninvasive nondestructive tool used in transportation applications such as evaluation and characterization of pavement systems, soils, and environmental problems. This report of the Transportation Research Board presents information on the principles, equipment, logistics, applications, and limitations of GPR pertaining to transportation applications. Selected case studies for which ground truth information is available are presented. In addition, an extensive bibliography and glossary are provided as well as appending information about GPR manufacturers from their literature.







HRIS Abstracts


Book Description