POREWATER PRESSURE IN CONCRETE

THE POREWATER PRESSURE IS ONE OF THE MOST NEGLECTED PARAMETERS IN CONCRETE TECHNOLOGY. RESEARCH IN SOIL MECHANICS DURING THE LAST TWO DECADES HAS EMPHASISED THE IMPORTANCE OF TREATING SOIL AS A TWO-PHASE MATERIAL. CONCRETE IS, HOWEVER, INVARIABLY TREATED AS A SINGLE-PHASE MATERIAL, AN ASSUMPTION WHICH IS CERTAINLY INVALID DURING THE EARLY PHASES OF SETTING. WHETHER IT IS EVER VALID CAN ONLY BE ESTABLISHED BY LONG-TERM MEASUREMENTS OF THE TENSION INDUCED IN THE WATER WHICH REMAINS IN THE FINE INTERSTICES, AFTER A PORTION OF THIS WATER HAS ENTERED INTO CHEMICAL COMBINATION WITH THE CEMENT. SUCH MEASUREMENTS DO NOT SEEM EVER TO HAVE BEEN MADE. SOME MEASUREMENTS HAVE BEEN MADE OF THE POREWATER PRESSURE IN FRESHLY-PLACED CONCRETE, AND THE RESULTS HAVE BEEN OF SUCH SIGNIFICANCE AS TO WARRANT A THOROUGH INVESTIGATION OF THIS PARAMETER. THREE CONSIDERATIONS WHICH RELATE TO CONDITIONS OF POSITIVE PORE WATER PRESSURE IN FRESHLY-MADE CONCRETE ARE PRESSURE OF CONCRETE AGAINST A VERTICAL SUPPORT, WORKABILITY AND PUMPED CONCRETE. THE INFLUENCE OF NEGATIVE POREWATER PRESSURE, THAT IS TENSION OR SUCTION INDUCED BY DRYING, EXTERNAL TENSION, OR BENDING, MAY BE OF EQUAL, IF NOT OF GREATER, IMPORTANCE THAN POSITIVE POREWATER PRESSURE, AS IS ILLUSTRATED IN EXAMPLES WHICH ARE GIVEN' CURING OF CONCRETE, CREEP OF CONCRETE; VARIATION OF STRENGTH OF CONCRETE WITH MOISTURE CONTENT, BOND STRENGTH, EFFECTIVENESS OF WATER IN ACHIEVING COMPACTION, POSITIVE POREWATER PRESSURE, NEGATIVE POREWATER PRESSURE. /AUTHOR/

  • Supplemental Notes:
    • Vol 61, No 2, PP 63-65
  • Authors:
    • Hanrahan, E T
  • Publication Date: 1966-2

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  • Accession Number: 00212379
  • Record Type: Publication
  • Files: TRIS
  • Created Date: May 1 1994 12:00AM