METHYLCHLOROSILANES AS ANTISTRIPPING AGENTS
STRIPPING, A MAJOR SOURCE OF FAILURE IN BITUMINOUS PAVEMENTS, IS CAUSED BY THE DISPLACEMENT BY WATER OF THE BITUMINOUS FILM ON THE SURFACE AND THE RESULTANT LOSS OF ADHESION BETWEEN THE AGGREGATE PARTICLES. STRIPPING OCCURS MOST FREQUENTLY WHEN SANDSTONE, CHERT, OR ANY ROCK CLASSIFIED BY GEOLOGISTS AS ACIDIC IS USED AS AGGREGATE. LIMESTONE, DOLOMITE, AND THE BASIC IGNEOUS ROCKS CAUSE RELATIVELY LITTLE TROUBLE. UNFORTUNATELY, LIMESTONE AND THE BASIC IGNEOUS ROCKS ARE NOT READILY AVAILABLE IN ALL LOCALITIES WHERE BITUMINOUS PAVEMENTS MUST BE CONSTRUCTED. THE SILICEOUS ROCKS ARE HYDROPHILIC, THAT IS, WATER ATTRACTING, WHILE LIMESTONE AND THE BASIC ROCKS ARE RELATIVELY HYDROPHOBIC. IF AN AGGREGATE WHICH IS HYDROPHILIC COULD BE TREATED TO MAKE IT HYDROPHOBIC, ITS RESISTANCE TO STRIPPING WHEN COATED WITH ASPHALT WOULD BE GREATLY IMPROVED. THIS PAPER DESCRIBES A METHOD FOR COATING A HYDROPHILIC AGGREGATE WITH A THIN, TIGHTLY-BOUND FILM OF SILICONE RESIN WHICH WILL PRESENT A HYDROPHOBIC SURFACE TO THE ASPHALT. THE AGGREGATE IS EXPOSED IN A SURFACE-MOIST CONDITION TO THE VAPOR OF A MIXTURE OF METHYLCHLOROSILANES, WHICH REACT WITH THE FILM OF MOISTURE ON THE AGGREGATE TO FORM A COATING OF SILICONE RESIN WITH A THICKNESS OF THE ORDER OF A FEW HUNDRED MOLECULES. AFTER EXPOSURE TO THE VAPOR, THE AGGREGATE IS STRONGLY HYDROPHOBIC. IN THE LABORATORY, SEVEN AGGREGATES WERE INVESTIGATED FOR STRIPPING, WITH AND WITHOUT THE SILICONE TREATMENT. ON THE BASIS OF THREE STRIPPING TESTS, IT WAS FOUND THAT THE PERFORMANCE OF SILICEOUS AGGREGATES CAN BE GREATLY IMPROVED BY TREATMENT WITH METHYLCHLOROSILANES. /AUTHOR/
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Supplemental Notes:
- Vol 31, pp 288-300, 11 FIG, 4 TAB, 20 REF. Distribution, posting, or copying of this PDF is strictly prohibited without written permission of the Transportation Research Board of the National Academy of Sciences. Unless otherwise indicated, all materials in this PDF are copyrighted by the National Academy of Sciences. Copyright © National Academy of Sciences. All rights reserved.
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Authors:
- Sanderson, F C
- Publication Date: 1952
Media Info
- Media Type: Digital/other
- Monograph Title: Proceedings of the Thirty-First Annual Meeting of the Highway Research Board, Washington, D.C., January 15-18, 1952
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Serial:
- Highway Research Board Proceedings
- Volume: 31
- Publisher: Highway Research Board
Subject/Index Terms
- TRT Terms: Absorptivity; Acidity; Aggregates; Bituminous pavements; Coatings; Hydrophobic properties; Resins; Rocks; Silicones; Stripping (Pavements)
- Uncontrolled Terms: Hydrophilic properties
- Old TRIS Terms: Acid rocks; Methylchlorosilanes; Silicone resins
- Subject Areas: Geotechnology; Highways; Materials;
Filing Info
- Accession Number: 00217121
- Record Type: Publication
- Files: TRIS, TRB
- Created Date: Aug 1 1971 12:00AM