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DISCUSSION ON DURABILITY OF CONCRETE

SHRINKAGE AND ITS INFLUENCE ON THE INTEGRITY AND DURABILITY OF CONCRETE PAVEMENTS IS DISCUSED. PHYSICAL LAWS CONTROLLING THE PERFORMANCE OF PLASTIC SUBGRADE SOILS AND SOIL TESTS, MIGHT BE USED IN STUDYING THE PERFORMANCE OF CEMENT MORTAR WHEN CHANGING FROM THE PLASTIC TO THE RIGID STATE. A THEORETICAL BASIS OF ATTACK IS SUGGESTED WHICH MAY ASSIST IN SOLVING CONCRETE DURABILITY: (1) SHRINKAGE OCCURRING DURING THE SETTING PERIOD OF CEMENT CONTROLS THE QUANTITY OF THE RESULTING CONCRETE, (2) DIFFERENCES IN AGGREGATE PARTICLES OR THE DEGREE OF THEIR CONSOLIDATION MAY CAUSE THE POTENTIAL PROPERTIES OF MORTARS TO BE MANIFESTED IN CONCRETE SLABS IN FORMS SUCH AS WELL DEFINED TRANSFERS OR LONGITUDINAL CRACKS, SHRINKAGE CRACKS, OR VERY SMALL MORTAR CRACKS, (3) DIFFERENCES IN THE CHARACTER AND ARRANGEMENT OF THE MORTAR PORES MAY CAUSE CRYSTAL GROWTH TO BE MANIFESTED DIFFERENTLY IN PAVEMENTS, AS BY SURFACE SCALING, DETERIORATION, HARMLESS CRYSTALS OCCURRING OVER SMALL SURFACE CRACKS, OR EFFLORESCENCE, (4) FOR EQUAL SHRINKAGE PROPERTIES, THE TYPE AND CHARACTER OF THE PORES IN THE CONCRETE DEPEND ON PHENOMENA SUCH AS TEMPERATURE VARIATION, RATE AND AMOUNT OF MOISTURE LOST, THE MANNER IN WHICH THE MORTAR, WHEN CHANGING FROM A PLIASTIC TO THE RIGID STATE, IS RESTRAINED FROM MOVING, AND (5) SUCCESSFUL TERMINATION OF THE INVESTIGATION MIGHT BE EXPEDITED BY THE INCLUSION OF STUDIES OF SYNTHETIC MORTARS POSSESSING PHYSICAL CHARACTERISTICS PRODUCED BY KNOWN ARBITRARY PROCEDURES. DATA ARE REVIEWED SUGGESTING THAT THE PRESENCE OF REINFORCEMENT MAY EXERT AN INFLUENCE ON THE MANNER IN WHICH CRYSTAL GROWTH MAY OCCUR. WITHIN THE LIMITS OF THE TEST DISCUSSED, THESE INDICATIONS ARE: (1) WHEN SLABS OF PLASTIC MATERIALS ARE RESTRAINED FROM SHRINKING IN A HORIZONTAL DIRECTION, SHRINKAGE IN A VERTICAL DIRECTION IS APT TO BE INCREASED, (2) THE STRENGTH OF MORTARS CURED DRY, DEPENDING UPON THE MOISTURE CONTENT OF THE CONCRETE WHEN TESTED, MAY EQUAL OR EVEN EXCEED THE STRENGTH OF MORTARS CURED WET, (3) THE DISTRIBUTION, INSTEAD OF THE WEIGHT OR REINFORCEMENT, IS IMPORTANT WITH RESPECT TO THE RESTRAINT OF MOVEMENT DUE TO MORTAR SHRINKAGE, (4) POSSIBILITIES FOR REDUCING THE MAGNITUDE OF SHRINKAGE IN MORTARS: BY REDUCING WATER LOSS, BY INCREASING THE POROSITY OF THE MORTAR BY MEANS OF ADMIXTURES OR CHEMICALLY INERT SUBSTANCES POSSESSING HIGH SHRINKAGE LIMITS, AND BY INCORPORATING WELL DISTRIBUTED STEEL REINFORCEMENT AS A MOVEMENT RESTRAINER, (5) A MOVEMENT RESTRAINER WHEN PLACED NEAR THE TOP OF A SHRINKING SLAB CAUSES THE SLAB EDGES TO WARP DOWNWARD AND WHEN PLACED NEAR THE BOTTOM CAUSES THE EDGES TO WARP UPWARD, (6) THE CHARACTER OF THE MORTAR VOIDS IS APT TO BE CONTROLLED BY THE SHRINKAGE PROPERTIES OF THE CEMENT PASTE, AND (7) LOSS OF MOISTURE DURING THE HARDENING PERIOD CAUSES MORTAR TO SHRINK.

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  • Supplemental Notes:
    • Vol 10, pp 164-205, 52 FIG, 1 TAB, 16 REF. 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:
    • Hogentogler, C A
    • Willis, E A
  • Publication Date: 1931

Media Info

  • Media Type: Digital/other
  • Monograph Title: Proceedings of the Tenth Annual Meeting of the Highway Research Board Held at Washington, D.C. December 11-12, 1930
  • Serial:

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Filing Info

  • Accession Number: 00213755
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Jun 1 1971 12:00AM