STATISTICAL SPECIFICATION STUDY INSTRUMENTS AND JOB CONTROL

MISSISSIPPI HAS USED A STATISTICALLY BASED SPECIFICATION FOR CONTROLLING CONTRACT DENSITIES FOR EIGHT YEARS, AND THIS REPORT IS A REVIEW OF THE CONTROL THAT HAS BEEN ACHIEVED UNDER THIS SPECIFICATION. SAND CONES AND WATER BALLONS ARE NORMALLY USED FOR DENSITY CONTROL IN MISSISSIPPI, BUT NUCLEAR INSTRUMENTS WERE INCLUDED IN THIS WORK TO DEMONSTRATE HOW THESE GAUGES FIT INTO THE CONSTRUCTION CONTROL PROGRAM. DATA WERE COLLECTED WITH CONVENTIONAL AND NUCLEAR INSTRUMENTS DURING A DEMONSTRATION PHASE OF THE STUDY AND THIS INFORMA- TION WAS ANALYZED ALONG WITH JOB CONTROL INFORMATION FROM FIVE INTERSTATE CONSTRUCTION PROJECTS. THE POTENTIAL PRECI- SION OF THE THREE INSTRUMENTS IS EXCELLENT AND WILL PROVIDE ABOUT THE SAME DEGREE OF JOB CONTROL IF CERTAIN MINIMUM RE- QUIREMENTS ARE MET IN THE SAMPLING PROGRAM. THE RESULTS OF THIS ANALYSIS INDICATE THAT NUCLEAR GUAGES PROVIDE THE BEST JOB CONTROL, AND SAND CONES THE POOREST WHEN PRESENT PRACTICES ARE CONSIDERED. THE DEMONSTRATION DATA WERE ALSO USED TO ASSIGN SOURCES OF VARIATION IN CONTROL TESTING. THE RESULTS INDICATE THAT UP TO HALF OF THE JOB CONTROL VARIANCE NOTED WAS ASSIGNABLE TO THE TEST METHOD, WITH THE MINIMUM TESTING VARIANCE ONE-FIFTH OF THE TOTAL. SOURCES OF VARIATION CONSIDERED WERE TESTING AND MATERIAL PLACEMENT, WITH OTHER SOURCES BEING INCLUDED UNDER THESE TWO HEADINGS. METHODS TO IMPROVE CONTROL TESTING INCLUDE THE USE OF INSTRUMENTS WITH GOOD PRECISION, THE USE OF PROPER SAMPLE SIZES, AND THE ESTABLISHMENT OF A CERTIFICATION PROGRAM FOR TECHNICIANS. /FHWA/

  • Supplemental Notes:
    • NO MSHD-RD-72-054
  • Corporate Authors:

    Mississippi State Highway Department

    Research and Development Division, P.O. Box 1850
    Jackson, MI  USA  39215
  • Authors:
    • Lanz, L J
  • Publication Date: 1972-8

Subject/Index Terms

Filing Info

  • Accession Number: 00214538
  • Record Type: Publication
  • Source Agency: Federal Highway Administration
  • Files: TRIS, USDOT, STATEDOT
  • Created Date: Apr 8 1973 12:00AM