THE EFFECT OF MICROCRACKING ON TIME-DEPENDENT DEFORMATIONS AND THE LONG-TERM STRENGTH OF CONCRETE

FOUR TYPES OF CRACKS ARE DISCUSSED: "PRE-EXISTING" AND "LOAD-INDUCED", BOTH TIME-INDEOENDENT; "SPONTANEOUS" AND "ENVIRONMENT-INDUCED", BOTH TIME-DEPENDENT. DEFORMATION INCREASES IN THE PRESENCE OF PRE-EXISTING CRACKS. STRENGTH IS REDUCED, BUT NOT TO THE EXTENT THAT MIGHT BE ANTICIPATED, AS CRACKS GRADUALLY STABILIZE IN THE PROCESS OF LOAD INCREASE. LOAD-INDUCED CRACKS ALSO INCREASE DEFORMATION BUT TO A SMALLER DEGREE. THE STRESS-STRAIN CURVE IS DISCUSSED IN TERMS OF CRACK PROPAGATION: THE PHASES OF SLOW BOND CRACKING, SLOW MATRIX CRACKING AND RAPID MATRIX CRACKING ARE DISTINGUISHED. A POSSIBLE MECHANISM OF SPONTANEOUS CRACKING, CONNECTED WITH THE PHENOMENON OF DELAYED ELASTICITY, NORMALLY REPRESENTED BY A KELVIN BODY, IS SUGGESTED. THIS HYPOTHESIS ALSO ACCOUNTS FOR THE LONG-TERM STRENGTH OF CONCRETE. THE NON-LINEARITY OF CREEP DUE TO CRACKING IS DISCUSSED. ALSO BRIEFLY REVIEWED AND DISCUSSED IS THE EFFECT OF CRACKING ON FATIGUE BEHAVIOR. FINALLY, THE EFFECT OF ENVIRONMENT-INDUCED CRACKS ON CREEP IS DEALT WITH. IT IS SUGGESTED THAT ATMOSPHERE TRANSITIONS FROM WET TO DRY AND VICE VERSA CAUSE CRACKING CONDUCIVE TO INCREASED CREEP. IN THE FIRST CASE IT IS DUE TO SHRINKAGE; IN THE SECOND TO STRESS-CORROSION. /A/RRL/

  • Supplemental Notes:
    • pp 176-189, 6 FIG, 36 REF
  • Corporate Authors:

    Cement & Concrete Assoc, London /UK

    /Proc Intl Conf, Sept 1965
    ,   USA 
  • Authors:
    • Glucklich, J
  • Publication Date: 1968

Subject/Index Terms

Filing Info

  • Accession Number: 00213018
  • Record Type: Publication
  • Source Agency: Road Research Laboratory /UK
  • Files: TRIS
  • Created Date: Oct 13 1970 12:00AM