SILICIFICATION OF CARBONATE AGGREGATES IN CONCRETE

IT IS DEMONSTRATED THAT THE TYPES OF CARBONATE AGGREGATE FROM THE CEDAR VALLEY FORMATION IN IOWA WHICH HAVE BEEN CLASSED AS ACCEPTABLE OR UNACCEPTABLE ON THE BASIS OF SERVICE RECORDS, CAN ALSO BE DIFFERENTIATED ON THE BASIS OF THEIR REACTIVITY WITH SILICA AND/OR FLUORIDE IN AQUEOUS SOLUTION. THIS REACTIVITY IS GENERALLY DIRECTLY RELATED TO THE PURITY OF THE ROCKS AS REGARDS THE AMOUNT OF ACID- INSOLUBLE MATERIAL PRESENT. IT IS ALSO SHOWN THAT REACTION SHELLS SUCH AS THOSE WHICH APPEAR IN UNACCEPTABLE AGGREGATES IN DISTRESSED CONCRETE CAN BE EXPERIMENTALLY GROWN BY PLACING THESE AGGREGATES IN CONCRETE BARS AND SUBJECTING THEM TO CONTROLLED LABORATORY CONDITIONS. THAT REACTION SHELL GROWTH IS DUE PRIMARILY TO THE INTRODUCTION OF SILICA DERIVED FROM THE CEMENT PASTE IS DEMONSTRATED BY PLACING AGGREGATE CHIPS IN EQUILIBRIUM WITH CEMENT PASTE AT 125 F FOR 50 DAYS AND COMPARING THE AMOUNT OF SILICA PRESENT IN THE AGGREGATE BEFORE AND AFTER THIS TREATMENT. A DEFINITE WEIGHT INCREASE IN THE AGGREGATE CHIPS IS ALSO NOTED. THE POSSIBILITY THAT THE SILICA MAY HAVE BEEN DERIVED FROM THE FINE QUARTZ AGGREGATE WAS STUDIED EXPERIMENTALLY WITH NEGATIVE RESULTS. /AUTHOR/

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrbbulletin/239/239-003.pdf
• Supplemental Notes:
  • No 239, pp 41-55, 31 FIG, 4 TAB, 10 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.
• Authors:
  • Bisque, Ramon E
  • Lemish, John
• Publication Date: 1960

Media Info

• Media Type: Digital/other
• Pagination: 15p
• Monograph Title: Physical and chemical properties of cement and aggregate in concrete
• Serial:
  • Highway Research Board Bulletin
  • Issue Number: 239
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Alternatives analysis; Before and after studies; Carbonates; Chippings; Concrete aggregates; Fluorides; Reactive aggregates; Silica
• Old TRIS Terms: Chips
• Subject Areas: Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00217750
• Record Type: Publication
• Files: TRIS, TRB
• Created Date: Aug 19 1994 12:00AM