Author : Jacob Vermillion
Publisher :
Page : 110 pages
File Size : 16,6 MB
Release : 2009
Category :
ISBN :
Author : M. Nagi
Publisher :
Page : 7 pages
File Size : 22,78 MB
Release : 1994
Category : Concrete
ISBN :
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.
Author : California. Department of Transportation. Division of New Technology, Materials, and Research
Publisher :
Page : 26 pages
File Size : 35,50 MB
Release : 1990
Category : Concrete
ISBN :
Author : Edwin C. Roshore
Publisher :
Page : 32 pages
File Size : 35,30 MB
Release : 1973
Category : Concrete
ISBN :
The purpose of this study was to investigate an alternative procedure for determining the water content of fresh concrete to replace or provide an alternate to the method now used in evaluating concrete mixer performance. A series of laboratory tests was conducted in which a microwave oven was used in parallel with an electric hot plate. Mortar samples of known water content and mortar samples sieved from concrete mixtures were dried in the microwave oven and on the hot plate. Water content was calculated and the results obtained through use of the two methods were compared. The results obtained indicated that a microwave oven is satisfactory for use in determining the water content of mortar samples taken from fresh concrete for concrete mixer performance tests. On the basis of the tests conducted, it is recommended that the microwave oven be designated as an alternate drying apparatus in the method of test for evaluating concrete mixer performance. (Author).
Author :
Publisher :
Page : 0 pages
File Size : 21,13 MB
Release : 2020
Category : Concrete
ISBN :
Author :
Publisher :
Page : 88 pages
File Size : 42,47 MB
Release : 1964
Category : Concrete
ISBN :
Author :
Publisher :
Page : 0 pages
File Size : 11,50 MB
Release : 1975
Category :
ISBN :
Quite a few methods have been recommended in the technical literature for the determination of the cement and water contents as well as the water/cement ratio of a fresh concrete. This paper discusses several of the published methods for determination of cement content, including the well-known Dunagan method and some of its variants, another mechanical method based on consistency measurements by two different techniques, and two physiocochemical methods. Although drying is simplest method for determining water content it is not accurate enough. Other methods of estimating the water content include calculating the weight of the solids in the concrete, using chemical means; measuring the electrical resistance or capacitance, or the thermal conductivity or the microwave absorption; and performing repeated consistency tests. The methods suggested for determination of the water/cement ratio are measuring essentially the water content.
Author : Joe G. Tom
Publisher : Transportation Research Board National Research
Page : 86 pages
File Size : 15,52 MB
Release : 1986
Category : Technology & Engineering
ISBN :
Author : Eric Samson
Publisher :
Page : 12 pages
File Size : 25,4 MB
Release : 2008
Category : Absorption
ISBN :
Experimental procedures such as ASTM C1585, "Standard Test Method for Measurement of Rate of Absorption of Water by Hydraulic-Cement Concretes," and ISO12572 have been recently developed to determine the rate of moisture transmission through hydrated cement systems. However, these methods do not provide an actual transport parameter that can be used in chloride ingress models to predict the service-life of concrete structures. This study focused on the development a reliable method to measure the nonlinear moisture diffusivity of concrete. The approach is based on the analysis of drying and wetting experiments performed with concrete samples of different thicknesses. The transport parameter is obtained by using Richards' water transport model to analyze the mass variations measured during the tests. The method was tested over a wide range of different concrete mixtures produced with different water/cement ratios. Results indicate that the nonlinear function used to reproduce the mass variation curves must exhibit a strong increase for high water content values. The water diffusivity equation derived from this analysis allows reproducing the behavior of concrete during both the drying and absorption experiments using the same water transport model.
Author : Joseph F. Lamond
Publisher : ASTM International
Page : 661 pages
File Size : 10,7 MB
Release : 2006
Category : Technology & Engineering
ISBN : 0803133677
