THE AIR REQUIREMENT OF FROST RESISTANT CONCRETE

ACCORDING TO THE HYDRAULIC-PRESSURE HYPOTHESIS OF FROST ACTION ON CONCRETE, THE EFFECTIVENESS OF ENTRAINED AIR DEPENDS ON VOID SPACING. THE THEORETICAL MAXIMUM PERMISSIBLE SPACING IS FOUND ANALYTICALLY TO BE A FUNCTION OF PASTE PROPERTIES, DEGREE OF SATURATION OF THE PASTE, AND RATE OF COOLING. APPLIED TO EXPERIMENTAL DATA FROM SIX DIFFERENT PASTES, COOLED AT 20 F. PER HOUR, THE THEORETICAL CALCULATIONS GAVE SPACING FACTORS RANGING FROM 0.01 TO 0.026 IN. OR MORE, DEPENDING ON PASTE CHARACTERISTICS AND VOID SIZE. A SPACING FACTOR FOR THE VOIDS IN HARDENED CONCRETE, AS WELL AS THE TOTAL VOLUME OF AIR, CAN BE CALCULATED FROM DATA OBTAINABLE BY THE LINEAR TRANSVERSE METHOD. THE NECESSARY MATHEMATICAL RELATIONSHIPS ARE GIVEN IN THIS PAPER. THE ACTUAL MAXIMUM SPACING FACTOR FOR CERTAIN FROST RESISTANT CONCRETES WAS ESTIMATED TO BE ABOUT 0.01 IN., A RESULT CONSIDERED TO BE IN EXCELLENT AGREEMENT WITH THAT OBTAINED FROM THE THEORETICAL CALCULATIONS. THE AIR REQUIREMENT IS THAT AMOUNT THAT MEETS THE SPACING REQUIREMENTS. IN GENERAL, THE AIR REQUIREMENT FOR A GIVEN RATE OF COOLING DEPENDS UPON THE PASTE CONTENT, THE SPECIFIC SURFACE OF THE VOIDS, AND THE MAXIMUM PERMISSIBLE SPACING FACTOR. WHEN VOIDS ARE TOO WIDELY SPACED TO PREVENT FAILURE OF SATURATED PASTE, FAILURE WILL ALSO OCCUR AT MOISTURE CONTENTS BELOW SATURATION. WITHIN LIMITS, THE DENSER THE PASTE THE LOWER THE DEGREE OF SATURATION AT FAILURE. /AUTHOR/

  • Supplemental Notes:
    • Vol 29, pp 184-211, 9 FIG, 7 TAB, 14 REF, 1 APP
  • Authors:
    • Powers, T C
    • Willis, T F
  • Publication Date: 1950

Media Info

  • Monograph Title: Proceedings of the Twenty-Ninth Annual Meeting of the Highway Research Board Held at Washington, D.C. December 13-16, 1949.
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00212682
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: May 21 1994 12:00AM