THE STRUCTURAL DESIGN OF CONCRETE PAVEMENTS - PART 2 - OBSERVED EFFECTS OF VARIATIONS IN TEMPERATURE AND MOISTURE ON THE SIZE, SHAPE, AND STRESS RESISTANCE OF CONCRETE PAVEMENT SLABS

RESULTS ARE PRESENTED AND EFFECTS DISCUSSED OF TEMPERATURE AND MOISTURE VARIATIONS ON THE SIZE, SHAPE, AND LOAD- CARRYING ABILITY OF PAVEMENT SLABS AS OBSERVED DURING THESE STUDIES. MEASUREMENTS OF TEMPERATURE, MOISTURE, THE EXPANSION AND CONTRACTION OF PAVEMENT SECTIONS, SUBGRADE RESISTANCE TO HORIZONTAL SLAB MOVEMENT, WARPING, THE EFFECT OF TEMPERATURE WARPING ON LOAD STRESSES ARE DESCRIBED. THE MAXIMUM TEMPERATURE DIFFERENTIALS ARE OBSERVED AT THE EDGES OF THE TEST SECTIONS WERE: (1) FOR A SIX-INCH UNIFORM- THICKNESS SECTION, 23 F, (2) FOR A 9-INCH UNIFORM-THICKNESS SECTION, 33 F, AND (3) FOR A 9-6-9 THICKENED EDGE SECTION, 33 F. A CYCLIC VARIATION IN SLAB LENGTH WAS OBSERVED THAT IS ENTIRELY DISASSOCIATED FROM TEMPERATURE CHANGES. RESISTANCE IN THE SUBGRADE TO HORIZONTAL SLAB MOVEMENT APPEARS TO CONSIST OF TWO ELEMENTS, (1) AN ELASTIC DEFORMATION OF THE SOIL HORIZONTALLY THAT IS PRESENT FOR ALL DISPLACEMENTS OF THE SLAB, AND (2) A FRICTIONAL RESISISTANCE THAT DEVELOPS ONLY AFTER A CERTAIN AMOUNT OF ELASTIC DEFORMATION HAS OCCURRED. IN PAVEMENT SLABS OF MODERATE LENGTH THE TENSILE STRESSES RESULTING FROM CONTRACTION WILL NOT BE LARGE FOR SUBGRADE SOILS OF THE TYPE USED IN THE TESTS. THE CHANGES IN SHAPE OF THE PAVEMENT SLAB RESULTING FROM RESTRAINED TEMPERATURE WARPING DO NOT CAUSE LARGE CHANGES IN THE CRITICAL STRESSES FROM APPLIED LOADS. SINCE THE CRITICAL STRESSES RESULTING FROM RESTRAINED WARPING ARE OPPOSITE IN SENSE TO THOSE CAUSED BY APPLIED LOADS IN THE CORNER REGION OF A PAVEMENT, THICKENING THE EDGE OF THE SLAB MAY BE EXPECTED TO INCREASE THE LOAD-CARRYING CAPACITY OF THE SLAB CORNER. THICKENING THE EDGE OF A LONG PAVEMENT SLAB WILL NOT TEND TO REDUCE TRANSVERSE CRACKING BUT WILL TEND TO REDUCE CORNER CRACKING. THE ANNUAL CYCLIC VARIATION IN MOISTURE CONDITIONS WITHIN THE CONCRETE PRODUCES A WARPING OF THE SLABS SURFACE SIMILAR TO THAT CAUSED BY TEMPERATURE.

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  • Accession Number: 00205584
  • Record Type: Publication
  • Files: NTL, TRIS
  • Created Date: Jun 10 1994 12:00AM