This report is the second in a series on a microwave drying system for rapid water content developed at the U.S. Army Engineer Waterways Experiment Station. The focus of the first report in the series was on development of equipment and the investigation of its use on inorganic soils. The focus of the present reported investigation is on microwave system drying of potentially difficult soils and earth materials, some of which have a history of requiring special treatment for ordinary conventional oven water content determination. Materials tested in this investigation are gravels, gravelly soils and earth-rock mixtures, dredged materials, fly ash, gypsum rich soils, calcite rich soils, organic clay, peat, and halloysite rich soils. Because specimen sizes too large to be practical for the microwave system would be required for representative samples in earth-rock mixtures, a procedure is outlined to determine water content based on knowledge of earth-rock composition. Gravels, dredged materials, organic clay, fly ash, and calcite rich soils are demonstrated to dry satisfactorily in the system using the same procedure as for normal inorganic soils. The system was used to dry materials containing amounts of organic material varying from about 2% to about 90%, and it was demonstrated that even though special software was required to dry highly organic soil (peat), the equipment dried these materials satisfactorily. The system failed to properly dry gypsum rich soils. Special software was required to dry peat and halloysite rich soils, and the development and documentation of this special software are given along with a version of the software for drying inorganic soils written for International Business Machines compatible computers. Additionally, an enhanced version of the original software written for the Commodore 64 computer is given. This version allows for calculations of dry density and allows input and output of many additional pieces of information for site and test identification and documentation. Data from use of the microwave system on two U.S. Army Corps of Engineers field projects are included along with an evaluation by field personnel who used the equipment. The results of all soil tests are included. It is concluded that the equipment will successfully dry all the potentially problem soils investigated to the conventional oven water content with the exception of gypsum rich soils.

  • Corporate Authors:

    U.S. Army Waterways Experiment Station

    Geotechnical Laboratory, 3909 Halls Ferry Road
    Vicksburg, MS  United States  39180-6199
  • Authors:
    • Gilbert, P A
  • Publication Date: 1990-12

Media Info

  • Features: Appendices; Figures; References; Tables;
  • Pagination: 202 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00610154
  • Record Type: Publication
  • Report/Paper Numbers: Tech Rept GL-90-26
  • Files: TRIS
  • Created Date: Jun 30 1991 12:00AM