Research has shown that one of the major contributing factors in early joint deterioration of portland cement concrete (pcc) pavement is the quality of the coarse aggregate. Conventional physical and freeze/thaw tests are slow and not satisfactory in evaluating aggregate quality. In the last 10 years the Iowa DOT has been evaluating X-ray analysis and other new technologies to predict aggregate durability in pcc pavement. Thermogravimetric analysis (TGA) of carbonate aggregate is evaluated. The TGA testing has been conducted with a DuPont TGA 2950 Thermogravimetric Analyzer. The equipment is controlled by an IBM-compatible computer. A DuPont Hi-Res software package allows for rapid testing while retaining high resolution. The carbon dioxide is driven off the dolomite fraction between 705 deg C and 745 deg C and off the calcite fraction between 905 deg C and 940 deg C. The graphical plot of the temperature and weight loss using the same sample size and test procedure is very accurate and repeatable. A substantial number of both dolomites and limestones (calcites) have been subjected to TGA testing. The slopes of the weight loss plot prior to the dolomite and calcite transitions does correlate with field performance. The noncarbonate fraction, which is nearly the same as the acid insolubles, can be determined by TGA for calcites and most dolomites. TGA has provided information that can be used to help predict the quality of carbonate aggregate.


  • English

Media Info

  • Features: Figures; References; Tables;
  • Pagination: p. 38-43
  • Monograph Title: Aggregate and pavement-related research
  • Serial:

Subject/Index Terms

Filing Info

  • Accession Number: 00625707
  • Record Type: Publication
  • ISBN: 0309054028
  • Files: TRIS, TRB, ATRI
  • Created Date: Jan 8 1993 12:00AM