IN-PLACE STRENGTH OF CONCRETE-A COMPARISON OF TWO TEST SYSTEMS

TWO NON-DESTRUCTIVE METHODS WERE EVALUATED FOR MEASURING THE STRENGTH OF CONCRETE. THE STUDY INCLUDED CONCRETES OF MODERATE TO HIGH STRENGTH MADE WITH NATURAL AND LIGHT WEIGHT AGGREGATES AND HAVING HIGH AND LOW SLUMP. THE TEST METHOD STUDY IS: (1) A NEW PROBE SYSTEM WHICH DEPENDS UPON THE PENETRATION OF A STEEL ROD FIRED FROM A STUD GUN DRIVER UNIT AS AN INDEX OF STRENGTH, AND (2) THE WIDELY USED IMPACT HAMMER WHICH MEASURES STRENGTH IN TERMS OF THE REBOUND OF A SPRING-DRIVEN PROJECTILE FROM A METAL PLUNGER HELD AGAINST THE CONCRETE SURFACE. THE CONCRETES WERE CAST WITH DIFFERENT SURFACE FINISHES AND TESTED AT DIFFERENT AGES IN BOTH MOIST AND DRY CONDITIONS AFTER FAVORABLE AND UNFAVORABLE CURING. THE TEST CONCRETES ENCOMPASSED WIDE RANGES IN STRENGTH, COARSE AGGREGATE, CURING AND FORM MATERIAL. CONCRETE STRENGTH WAS DETERMINED BY TESTS OF CORES AND MOLDED CYLINDERS. BOTH NON-DESTRUCTIVE METHODS WERE FOUND TO CORRELATE FAIRLY WELL WITH STRENGTHS MEASURED ON CORES DRILLED FROM THE SAME CONCRETES. BASED ON THESE TESTS, THE PROBE SYSTEM DOES NOT SUPPLY THE ACCURACY REQUIRED IF IT IS TO REPLACE CONVENTIONAL CORE TESTS. HOWEVER, IT WILL BE USEFUL IN MUCH THE SAME MANNER THAT THE REBOUND HAMMER IS USEFUL TO LOCATE AREAS OF RELATIVE LOW OR RELATIVE HIGH STRENGTH CONCRETES IN STRUCTURES.

  • Supplemental Notes:
    • 39th Ann MtG, 14 PP, 9 FIG, 4 TAB
  • Corporate Authors:

    National Ready Mixed Concrete Association

    900 Spring Street
    Silver Spring, MD  USA  20910
  • Authors:
    • Gaynor, R D
  • Publication Date: 1969-1

Media Info

Subject/Index Terms

Filing Info

  • Accession Number: 00215255
  • Record Type: Publication
  • Files: TRIS
  • Created Date: Apr 27 1970 12:00AM