STRENGTH LOSSES IN HEAT CURED CONCRETE

THE CAUSES OF STRENGTH LOSSES WERE STUDIED DURING 28 DAYS IN HEAT CURED CONCRETE COMPARED WITH NORAMLLY CURED CONCRETE IN ORDER TO FIND A MEANS OF AVOIDING SUCH LOSSES. THERE ARE TWO DIFFERENT CAUSES: PHYSICAL AND CHEMICAL. THE PHYSICAL CAUSES CONSIST OF INCREASED POROSITY AND CRACKING, THE CHEMICAL CAUSES CONSIST OF DIFFERENCES IN THE CHEMICAL COMPOSITON, MICRO-STRUCTURE AND DEGREE OF HYDRATION BETWEEN HEAT CURED AND NORMALLY CURED CEMENT PASTE. THE PHYSICAL CAUSES DOMINATE. THE EXPERIMENTS WERE DESIGNED TO TEST A HYPOTHESIS FOR THE PHYSICAL MODE OF BEHAVIOUR IN HEAT CURED CONCRETE, E.G. THAT IF THE TENSILE STRENGTH OF THE CONCRETE IS NOT SUFFICIENT TO WITHSTAND THE PRESSURE IN THE AIR PORES THE CONCRETE WILL CRACK. IN TWO SERIES OF EXPERIMENTS CONCRETE WITH VARYING TENSILE STRENGTHS WAS EXPOSED TO HEAT CURING AND TO ENSUING PORE PRESSURE. THE EXPERIMENTS REQUIRED NON-TRADITIONAL TYPES OF EQUIPMENT AND WERE DESIGNED TO TEST VOLUMETRIC CHANGE, AIR MOVEMENT, TENSILE STRENGTH AND DEFORMATION PROPERTIES. IT IS CONCLUDED THAT TO REDUCE THE PHYSICAL EFFECTS, THREE METHODS CAN BE USED (A) TO COUNTERACT PORE PRESSURE, BY USING CLOSED FORMS OR LETTING THE CONCRETE ATTAIN A MINIMUM TENSILE STRENGTH BEFORE HEAT CURING, (B) TO ELIMINATE THE PORE PRESSURE, BY HEATING THE CONCRETE BEFORE CASTING, OR BY ELIMINATING THE AIR PORES, OR, (C) TO LET THE CONCRETE CRACK AND TO REPAIR IT AFTERWARDS BY REVIBRATION AFTER HEATING. /TRRL/

Media Info

  • Features: Figures; Photos; References; Tables;
  • Pagination: 135 p.
  • Serial:
    • Issue Number: 43

Subject/Index Terms

Filing Info

  • Accession Number: 00214401
  • Record Type: Publication
  • Source Agency: Transport and Road Research Laboratory (TRRL)
  • Report/Paper Numbers: R&d Rpt
  • Files: TRIS
  • Created Date: Dec 11 1973 12:00AM