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|Title:||Investigation of colorless and water-based concrete curing compounds|
|Authors:||United States. Army. Office of the Chief of Engineers.|
Derrington, Clara F.
|Publisher:||Concrete Laboratory (U.S.)|
Engineer Research and Development Center (U.S.)
|Series/Report no.:||Technical report (U.S. Army Engineer Waterways Experiment Station) ; C-69-7.|
Abstract: Elven compounds designated as colorless and two designated as water-based were evaluated for their suitability for curing of concrete and for their lack of color. All met present requirements for sprayability, drying time, and flash point. Only ten met the moisture-retention requirements. The three that failed the moisture test were one colorless type (styrene-acrylate resin) and both water-based compounds. An infrared spectrophotometer was used to identify and characterize each of the materials. Infrared analysis revealed that the 11 colorless materials represent 5 different chemical classes: 4 chlorinated rubbers, 2 modified styrene-butadienes, 1 phthalic alkyd, 3 carboxylated hydrocarbons, and 1 styrene-acrylate. Both water-based materials were identified as sodium silicate liquids. Infrared measurements were used to detect chemical and physical changes of the colorless materials when exposed to laboratory conditions and natural sunlight. The materials ranged from light yellow to dark reddishbrown and were rated from 1 to 18 on a standard- color comparator. Generally, mortar specimens coated with the curing compounds lightened in color when subjected to both a controlled temperature humidity cabinet and ultraviolet radiation in a weatherometer. However, upon being subjected to alternate cycles of rainfall and ultraviolet radiation in the weatherometer, some of the coated surfaces continued to lighten and the curing compounds washed off, while some became mottled and unattractive. There was no correlation between original color of the curing compound and color of the coated mortar surfaces either before or after exposure. Coating materials in the same chemical classes responded to weathering in a similar manner. Mortar surfaces coated with two of the carboxylated hydrocarbons possessed a dull finish and appeared more natural looking with fewer signs of mottling than any of the other coated.surfaces.
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