STATISTICAL QUALITY CONTROL IN PCC PAVEMENTS

QUALITY CONTROL FOR PORTLAND CEMENT CONCRETE (PCC) PAVEMENTS AND THEIR COMPONENT PARTS WAS STATISTICALLY STUDIED IN A FIELD PROJECT APPROXIMATELY 8 MILES LONG. STANDARD FIELD TESTS ON FRESH CONCRETE AND STANDARD LABORATORY TESTS ON HARDENED CONCRETE, COARSE AND FINE AGGREGATE, AND CEMENT WERE RUN ON AN ADEQUATE NUMBER OF SAMPLES. NINETY-FIVE PAVEMENT THICKNESS MEASUREMENTS WERE TAKEN, AND 400 CONCRETE CYLINDERS WERE TESTED. FOR ALL THE OTHER CHARACTERISTICS, SUCH AS SLUMP, AIR CONTENT, GRADATION , DURABILITY, LOS ANGELES LOSS, SAND EQUIVALENT, FINENESS, AND PERCENT PASSING NO. 200 SIEVE, 200 OBSERVATIONS WERE MADE. THE TYPICAL STATISTICAL PARAMETERS, I.E., TESTING, SAMPLING AND MATERIAL VARIANCES, STANDARD DEVIATION AND ARITHMETIC MEAN, WERE CALCULATED AND FREQUENCY DISTRIBUTION CURVES DRAWN. IN NEARLY ALL CASES, THE ARITHMETIC MEAN OF THE MEASURED CHARACTERISTIC COMPLIED WELL WITH THE SPECIFICATIONS. HOWEVER, THE RELATIVELY HIGH VALUES OF STANDARD DEVIATION AND OF THE TESTING VARIANCE SHOULD RAISE SERIOUS QUESTIONS ON THE PHILOSOPHY UNDERLYING THE EXISTING ACCEPTANCE-REJECTION PROCEDURES IN PCC PAVEMENTS. UPPER AND LOWER CONTROL LIMITS, ESPECIALLY THOSE BASED ON AVERAGE VALUE, SHOW CONCLUSIVELY THAT UNFIT MATERIAL IS SOMETIMES ACCEPTED. ALSO, LARGE VALUES OF THE TESTING VARIANCE SUGGEST THAT STANDARD TESTS NEED SOME REFINEMENT, IF NOT A COMPLETE MODIFICATION, TO REDUCE THEIR INHERENT VARIANCE. /AUTHOR/

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  • Accession Number: 00212330
  • Record Type: Publication
  • Files: TRIS, TRB
  • Created Date: Oct 13 1994 12:00AM