ILLINOIS DEVELOPS HIGH PRESSURE AIR METER FOR DETERMINING AIR-CONTENT OF HARDENED CONCRETE

A DESCRIPTION IS MADE OF THE DEVELOPMENT OF APPARATUS AND TEST PROCEDURE FOR DETERMINING AIR CONTENT OF HARDENED CONCRETE, UTILIZING PRESSURE AND BOYLE'S LAW. THE METHOD IS FOUND TO BE A VALUABLE ADDITION TO THE PROCEDURE FOR CONTROL OF CONCRETE PRODUCTION, & OFFERS EXCELLENT PROMISE FOR VOID DETERMINATION IN BITUMINOUS CONCRETE SPECIMENS. FOR SATISFACTORY PENETRATION OF THE PRESSURE TO THE ENTRAINED AIR, THE SPECIMENS MUST BE OVER-DRIED AND SATURATED IMMEDIATELY PRIOR TO TESTING. A TEST PRESSURE OF 5000 PSI., THE DESIGN CAPACITY OF THE APPARATUS, WAS FOUND SATISFACTORY AND BETTER ADAPTED TO CONCRETE OF ALL AIR CONTENTS THAN LOWER PRESSURES. THE APPARATUS WAS BUILT EXPECIALLY FOR ROUTINE TESTING OF CORES DRILLED FROM NEWLY CONSTRUCTED PAVEMENTS, BUT THE TEST SPECIMEN SIZE DOES NOT APPEAR TO BE NOTEWORTHY IN AIR CONTENT DETERMINATION, EXCEPT THAT RELATIVELY THIN PIECES OF CONCRETE APPEAR TO SHOW SLIGHTLY LOWER AIR CONTENTS THAN CYLINDRICAL SPECIMENS. GOOD REPRODUCIBILITY OF AIR CONTENTS ARE OBTAINED IN INDEPENDENT TESTS OF THE SAME SPECIMENS AT DIFFERENT AGES, AND THE METHOD PROVIDES EXCELLENT DIFFERENTIATION BETWEEN CONCRETES OF DIFFERENT AIR CONTENTS. HOWEVER, THE AIR CONTENTS OBTAINED GENERALLY ARE A LITTLE HIGHER THAN THOSE OBTAINED FOR THE SAME CONCRETE IN PLASTIC STATE. THIS IS DUE, PARTLY TO THE COMPRESSIBILITY OF THE CONCRETE SPECIMENS UNDER THE HIGH PRESSURE, WHICH WOULD REGISTER ON THE INDICATOR AS ENTRAINED AIR. AT PRESENT, THE AIR CONTENTS DETERMINED ARE CORRECTED FOR THIS DEVIATION, BUT AN ATTEMPT WILL BE MADE TO INCLUDE THE COMPRESSIBILITY OF THE CONCRETE IN THE APPARATUS RECALIBRATION. A SATISFACTORY AGREEMENT WAS FOUND BETWEEN AIR CONTENTS OF CYLINDRICAL SPECIMENS DETERMINED WITH THE APPARATUS AND AIR CONTENTS DETERMINED SUBSEQUENTLY BY MICROSCOPIC MEANS. AIR CONTENTS OF PLASTIC CONCRETE CAN BE DETERMINED WITH GOOD ACCURACY IN THE HIGH PRESSURE APPARATUS INDICATING THE SOUNDESS OF THE METHOD. THOUGH THE EXPERIMENTAL WORK IS NOT CONSIDERED COMPLETED, THE APPARATUS HAS BEEN USED DURING THE LAST TWO YEARS, WITH APPARENTLY GOOD RESULTS, FOR ROUTINE DETERMINATIONS OF THE AIR CONTENTS OF CORES DRILLED FROM THE PAVEMENTS. /AUTHOR/

  • Supplemental Notes:
    • Vol 35, pp 424-435, 7 FIG, 2 PHOT, REF, 1 APP
  • Authors:
    • Lindsay, J D
    • Kennedy, T B
  • Publication Date: 1956

Media Info

  • Monograph Title: Proceedings of the Thirty-Fifth Annual Meeting of the Highway Research Board, Washington, D.C., January 17-20, 1956
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00213972
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Aug 15 1971 12:00AM