STATISTICAL CORRELATION AND VARIANCE PROJECT RELATED TO THE QUALITY CONTROL OF HIGHWAY MATERIALS

TWENTY-EIGHT DAY STRUCTURAL AND PRESTRESSED CONCRETE HISTORICAL COMPRESSIVE STRENGTH DATA FROM 8000 CYLINDERS PREPARED IN 1964 BY CENTRAL LABORATORY PERSONNEL AT THE JOB SITE WAS STATISTICALLY ANALYZED TO ESTIMATE CONFORMANCE TO EXISTING CRITERIA. DATA FROM 10,000 CYLINDERS PREPARED BY PROJECT BASED PERSONNEL WAS NOT USED IN THE ANALYSIS. TESTING, SAMPLING, MATERIAL AND TOTAL VARIANCE, ST'D DEV., MEAN COEFFICIENT OF VARIATION WAS DETERMINED FOR EACH PROJECT SUB LOT. ACCEPTANCE PLANS FOLLOWING PRINCIPLES OF MIL,STD 414, ST'D DEVIATION UNKOWN, WAS PROPOSED FOR USE ON A TRIAL BASIS. ACCEPTABLE QUALITY LEVELS (AGE) OF 2.5% FOR PRESTRESSED CONCRETE (5000 PSI MINIMUM) AND 6.5% FOR OTHER STRUCTURAL CONCRETE (3000 PSI MINIMUM) WERE SELECTED TO BEST APPROXIMATE COMPUTED TEST VALUES. FOR CONCRETE USED IN BRIDGE SUPERSTRUCTURES AN AQL OF 1.5% (5.5% ESTIMATE OF PERCENT DEFECTIVE) WAS USED TO REDUCE THE RISK OF ACCEPTING POOR QUALITY CONCRETE. AN ATTEMPT WAS MADE TO HOLD ALPHA AND BETA RISKS TO A COMMON 15% DEFECTIVE COMMENSURATE WITH SAMPLE SIZE, LOT SIZE, AND CRITICALNESS OF USE. AN ACTION AND REDUCED PAYMENT PLAN WAS SUGGESTED FOR NONCONFORMING CONCRETE. COMPARISONS WERE MADE WITH ACI 214 SUGGESTED MAXIMUM 10 PERCENT DEFECTIVE. SUGGESTIONS WERE MADE TO REVISE STATES EXISTING PRESTRESSED CONCRETE SPECIFICATION TO REDUCE THE RISK OF ACCEPTING EXCESSIVELY POOR QUALITY MATERIALS. /BPR/

  • Supplemental Notes:
    • Hpr, 7711
  • Corporate Authors:

    New Jersey Department of Transportation

    1035 Parkway Avenue
    Trenton, NJ  United States  08625

    Bureau of Public Roads /US

    400 7th Street, SW
    Washington, DC  United States  20590
  • Publication Date: 1968-9

Subject/Index Terms

Filing Info

  • Accession Number: 00214480
  • Record Type: Publication
  • Source Agency: Bureau of Public Roads /US
  • Files: TRIS, STATEDOT
  • Created Date: Mar 18 1994 12:00AM