AN OCCURRENCE OF ALKALI-REACTIVE CARBONATE ROCK IN VIRGINIA

THE DISCOVERY THAT CONCRETE AGGREGATES WERE NOT INERT BUT COULD PARTICIPATE IN CHEMICAL REACTIONS WITH CERTAIN CEMENT COMPOUNDS STIMULATED AN INTERNATIONAL RESEARCH EFFORT THAT HAS RESULTED IN THE RECOGNITION OF SEVERAL DISTINCT MECHANISMS BY WHICH THESE REACTIONS MAY REDUCE THE DURABILITY OF CONCRETE. RECENTLY, ATTENTION HAS BEEN DRAWN TO A REACTION INVOLVING THE CEMENT ALKALIES AND A TYPE OF ARGILLACEOUS DOLOMITIC LIMESTONE. AGGREGATES SUSCEPTIBLE TO THIS TYPE OF REACTION WERE FOUND IN ILLINOIS AND INDIANA. THE REACTION DIFFERS FROM WELL-KNOWN ALKALI-SILICA REACTION IN THAT NO VISIBLE GEL OR REACTION PRODUCT IS FORMED NOR IS ANY RIM FORMATION APPARENT ON THE REACTED AGGREGATE PARTICLES AS IS THE CASE WITH THE SILIFICATION REACTION. THE PERFORMANCE IN CONCRETE OF AN AGGREGATE FROM KINGSTON, ONTARIO, MET ALL PHYSICAL AND CHEMICAL TESTS AND YET WAS SHOWN TO BE ALKALI REACTIVE. PATTERN CRACKING DEVELOPED IN FIELD CONCRETE CONTAINING THIS AGGREGATE COMPARATIVELY SOON AFTER PLACING. THE CRACKS SURROUNDED AREAS FROM 2 TO 4 INCHES ACROSS AND THE CONCRETE BETWEEN THE CRACKS WAS RELATIVELY SOUND. THE EXPANSION DECREASED WITH MAXIMUM AGGREGATE SIZE, A BEHAVIOR CONTRARY TO OTHER TYPES OF CEMENT-AGGREGATE REACTIONS. THE CONCLUSION WAS THAT ROCKS COMPOSED OF NEAR EQUAL PROPORTIONS BY WEIGHT OF DOLOMITE AND CALCITE COULD BE REGARDED AS SUSPECT AND THAT A POSSIBLE CONNECTION EXISTED BETWEEN THE EXPANSIVE REACTIVITY AND THE DEDOLOMITIZATION REACTION (REPLACEMENT OF DOLOMITE BY CALCITE AND BRUCITE). IN CONCRETE, THE ALKALI CARBONATE WOULD REACT WITH HYDRATION PRODUCTS OF CEMENT TO REGENERATE ADDITIONAL ALKALI. THE EXPANSIVE TENDENCY OF ROCKS WAS MEASURED BY LABORATORY TEST. /AUTHOR/

• Record URL:
  http://onlinepubs.trb.org/Onlinepubs/hrbbulletin/355/355-002.pdf
• Supplemental Notes:
  • 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:
  • Newlon Jr, Howard H
  • Sherwood, W Cullen
• Conference:
  • 41st Annual Meeting of the Highway Research Board
  • Location: Washington DC, United States
  • Date: 1962-1-8 to 1962-1-12
• Publication Date: 1962

Media Info

• Media Type: Digital/other
• Features: Appendices; Figures; References; Tables;
• Pagination: pp 27-44
• Monograph Title: Carbonate aggregate reactions and steam curing of concrete
• Serial:
  • Highway Research Board Bulletin
  • Issue Number: 355
  • Publisher: Highway Research Board

Subject/Index Terms

• TRT Terms: Alkali; Alkali aggregate reactions; Calcites; Clastic rocks; Concrete; Concrete aggregates; Cracking; Dolomite; Durability; Gels; Hydration; Laboratory tests; Measurement; Rocks
• Uncontrolled Terms: Concrete cracking
• Old TRIS Terms: Alkalies; Rock measurement
• Subject Areas: Geotechnology; Highways; Materials;

Filing Info

• Accession Number: 00217587
• Record Type: Publication
• Files: TRIS, TRB, ATRI
• Created Date: Jun 3 1994 12:00AM