THE EFFECTS OF TEXTURAL AND EXTERNAL RESTRAINTS ON THE EXPANSION OF REACTIVE CARBONATE AGGREGATES

CERTAIN PHYSICAL, MECHANICAL, AND COMPOSITIONAL PROPERTIES WERE DETERMINED FOR SELECTED CROSS SECTIONS OF CARBONATE ROCK SAMPLES. INVESTIGATIONS WERE CONDUCTED ON THE RELATIONSHIP OF THESE PROPERTIES TO THE EXPANSION OF THE ROCK IN AN ALKALINE SOLUTION. EXPANSION OF THE ROCK SPECIMENS WAS MEASURED BOTH IN THE RESTRAINED AND IN UNRESTRAINED CONDITIONS AND A THEORY DEVELOPED FROM A SPHERICAL MODEL OF A TWO-PHASE SYSTEM COMPOSED OF EXPANDING ELASTIC PARTICLES ENCLOSED WITHIN AN ELASTIC MATRIX, WHICH APPEARS TO GIVE A GOOD APPROXIMATION OF THE EXPANSION OF CONCRETE RESULTING FROM THE EXPANSION OF CERTAIN VOLUMES OF EXPANSIVE AGGREGATE. IT WAS FOUND THAT THE MODULUS OF ELASTICITY OF EACH PHASE OF THE SYSTEM HAS A SIGNIFICANT INFLUENCE ON THE DEGREE TO WHICH THE TOTAL SYSTEM WILL EXPAND. IT WAS ALSO FOUND THAT THE EXPANSION OF CARBONATE ROCK IS DEPENDENT ON THE ROCK'S TEXTURE (OR STRUCTURAL FABRIC) AND DOLOMITE CONTENT, AND WITH THE NECESSARY DOLOMITE CONTENT EXPANSION INCREASES WITH HIGHER POROSITIES, HIGHER ABSORPTION, LOWER SPECIFIC GRAVITIES, LOWER COMPRESSIVE STRENGTHS, AND LOWER MODULI OF ELASTICITY. FOR THE DEGREE OF RESTRAINT USED, STRESSES OF THE ORDER OF 2200 PSI WERE DEVELOPED BY THE EXPANSION OF SOME ROCK SAMPLES. IT IS APPARENT THAT THE USE OF HIGHER RESTRAINT OR LONGER DURATION OF TEST WOULD HAVE RESULTED IN HIGHER FORCES BEING EXERTED BY THE EXPANDING ROCK SPECIMENS AND, SINCE THE TENSILE STRENGTH OF CONCRETE IS NORMALLY LESS THAN 1000 PSI, THAT THERE IS LITTLE DOUBT THAT EXPANSIVE CARBONATE AGGREGATES CAN EXERT PRESSURES OF SUFFICIENT MAGNITUDE TO CAUSE FRACTURE IN CONCRETE MADE WITH CEMENTS HAVING HIGH ALKALI CONTENT. /BPR/

• Supplemental Notes:
  • Hpr, 0458
• Corporate Authors:

  Virginia Highway Research Council

  Charlottesville, VA  United States 

  Federal Highway Administration

  1200 New Jersey Avenue, SE
  Washington, DC  United States  20590

  Bureau of Public Roads /US

  400 7th Street, SW
  Washington, DC  United States  20590
• Authors:
  • Hilton, M H
• Publication Date: 1968-9

Subject/Index Terms

• TRT Terms: Absorption; Alkali aggregate reactions; Carbonate rocks; Compressive strength; Concrete; Dolomite; Expansion; Fracture mechanics; Modulus of elasticity; Physical properties; Porosity; Reactive aggregates; Rocks; Specific gravity; Stresses; Texture
• Uncontrolled Terms: Fracture
• Old TRIS Terms: Rock properties
• Subject Areas: Geotechnology; Highways;

Filing Info

• Accession Number: 00217478
• Record Type: Publication
• Source Agency: Bureau of Public Roads /US
• Files: TRIS, USDOT
• Created Date: Mar 18 1994 12:00AM