QUALITY CONTROL OF COMPACTION IN EARTHWORKS AND PAVEMENTS BY NUCLEAR METHODS

Present density and moisture control methods are fast becoming inadequate, especially with the increased use of high speed, large capacity earth moving and compaction equipment. Speed in the primary advantage of testing by nuclear methods. The result of a test is immediately available to both engineer and contractor. Compaction inadequacies may be corrected immediately before subsequent lifts of material have been laid. Decisions on rejection or acceptance can be made on the spot, and the appropriate action taken before the weather takes a hand in proceedings. In cases of doubt, further tests can quickly be made. If further compactive effort is required, immediate checks can be made to determine whether this has been effective. An invaluable application of nuclear Hidrodensimeters is determination of the moisture content of borrow areas before the material is placed, thus preventing the use of unsuitable materials, eliminating rule of thumb methods, guess work, "getting away with it", and other hopeful measures which are used in a surprising number of cases. Greater coverage of a job is possible, in the form of many more up to date tests within the same time as those recorded by conventional methods. Thus a truer picture of "as built" conditions is provided. The mobility of the equipment makes it possible for several sites to be checked in one day. The testing organization becomes more flexible, as it is not as dependent on static laboratory based equipment. A qualified soil technician is essential for itelligent operation of the instrument, and for intelligent interpretation of results, but total labor requirements are considerably reduced. Applications of the nuclear method not previously discussed, include determination of the density and asphalt content (while still hot) of thick lift asphalt pavements, in place of expensive conventional coring techniques. Greater coverage and non-destructive properties contribute to its value in this application. Evaluation of compaction equipment and materials in test banks, or in actual site conditions can be readily carried out on the same sites, following subsequent roller passes of smooth wheeled equipment. This non-destructive technique is of great value for investigating the performance of road materials and road rollers. The in situ density of concrete can readily be checked to a high degree of accuracy and rapid moisture determination of timber is possible. In the absence of weight-bridges, the loading of vehicles carrying soils and aggregates can be checked, if the volume of the load is known. In summary, nuclear density and moisture test methods are comparable in accuracy with conventional test methods, and in some applications superior, are more economical on a long term basis, and offer greater coverage, simplicity, and flexibility of operation. Of greatest importance is the ability of these instruments to provide almost instantaneous results of tests.

Media Info

  • Features: Appendices; Figures; Tables;
  • Pagination: p. 452-465
  • Serial:
    • Volume: 2

Subject/Index Terms

Filing Info

  • Accession Number: 00263105
  • Record Type: Publication
  • Report/Paper Numbers: Proceeding
  • Files: TRIS
  • Created Date: Nov 12 1974 12:00AM