Almost all rigid-pavement design procedures used today include consideration of the fatigue strength of concrete, but the fatigue curves used do not take into account the effects of entrained air. This paper presents the results of a study of the flexural fatigue strength of concrete in which the only variable was the percentage of entrained air. All other variables (e.g., type of cement, water-cement ratio, and type of aggregate) were held constant. Five sets of concrete beams that had air contents that varied from 2.8 percent (natural air, i.e., no air-entraining agent added) to 11.3 percent but a constant water-centment ratio of 0.41 were tested under one-third-point loading. The stresses were varied from zero to a predetermined maximum that corresponded to a percentage of the modulus-of-rupture strength of the given beam. Within each air-content group, a minimum of five beams were tested at each of four stress levels: 60, 70, 80, and 90 percent of modulus of rupture. A total of 112 specimens of 15.2 - 15.2-cm (6 x 6-in.) cross section were tested. The results are presented as fatigue curves that relate the ratio flexural stress; modulus of rupture to the number of allowable load repetitions and show a decrease in fatigue strength as air content increases. /Author/

Media Info

  • Media Type: Print
  • Features: Figures; References; Tables;
  • Pagination: pp 20-23
  • Monograph Title: Analysis of pavement systems
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00193376
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: May 11 1979 12:00AM