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|Title:||Investigation of methods for extraction, detection, and identification of water-soluble admixtures in concrete|
|Authors:||United States. Assistant Secretary of the Army (R & D).|
Bean, Dennis L.
Husbands, Tony B.
|Publisher:||Concrete Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Miscellaneous paper (U.S. Army Engineer Waterways Experiment Station) ; C-78-9.|
Abstract: Methods for detecting, identifying, and quantitatively measuring carbohydrates and salts of hydroxylated carboxylic-acid admixtures in concrete were investigated. Two published methods for detecting sugar and an unpublished method for detecting both sugar and sodium gluconate were evaluated. Other methods investigated included: thin-layer chromatography, infrared spectroscopy, and high-pressure liquid chromatography. Sugar could be detected in cement mortar at an early age using both of the two published methods and the unpublished method. Approximately quantitative measurement of sugar could be made by the unpublished method and a UV spectrophotometer. Quantitative measurements with age indicated that sugar was being converted to another compound. Because of this conversion, sugar could not be detected by the UV method in 7-day-old mortar specimens containing 0.05 percent sugar. An infrared spectroscopic method for identifying and quantifying salts of carboxylic acids in concrete was investigated and was found to be unsatisfactory because of interference from water-soluble constituents in the cement paste. Six organic solvents were investigated for extracting salts of carboxylic acids from concrete, and none of the solvents were found suitable. Thin-layer chromatography (TLC) methods were found not to be sufficiently sensitive to detect the small amounts of carbohydrates present in concrete. Salts of carboxylic acids could not be separated using TLC, by the methods tried. A combination TLC and fluorometric method for quantifying carbohydrates was investigated. This method showed some promise but could not be fully evaluated because of the lack of a scanning fluorometer. A high-pressure liquid chromatography (HPLC) method for separating and identifying the admixtures was investigated. The admixtures could not be detected because of interference and the low concentration of the admixtures in concrete. HPLC shows promise as a method and warrants further investigation.
|Rights:||Approved for public release; distribution is unlimited.|
|Appears in Collections:||Miscellaneous Paper|
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