METHODS FOR DETERMINING THE DEGREE OF COMPACTION IN FRESH CONCRETE

METODER FOER BESTAEMNING AV KOMPRIMERINGSGRAD HOS FAERSK BETONG

This investigation aimed at developing methods for determining the degree of compaction in fresh concrete. Three methods were studied, a radioactive method, an electric method and a dynamic method. The radioactive method is based on measuring the density by means of gamma radiation. Cesium-137 has been used as a radiation source. A measurement precision corresponding to a standard deviation of 4-14 kg/cubic metre was achieved in repeated measurements on the same concrete mixes. Experience obtained for measurements on hardened concrete indicates that the method offers adequate accuracy. The investigation of the electric method embraced capacitance, impedance and resistance measurements. The measurements were carried out between 2 metal plates in contact with the concrete. The experiments with impedance and resistance measurements indicated a clear relation between the measurement unit and the degree of compaction. The result did, however, indicate major systematic errors. The results from measurements carried out on concrete with varying compositions indicate that the method is not suitable for determining the degree of compaction in unknown concrete. The investigation indicated that the measurement accuracy obtained in impedance and resistance measurements could be improved. The investigation of the dynamic measuring method embraced a study of the propagation time and wave characteristics in shock waves and of the attenuation of resonance frequencies for continuous sine waves within the frequency range 2-B0 khz. These experiments did not result in the development of any usable method. (TRRL)

  • Corporate Authors:

    Cement and Concrete Research Institute

    Drottning Kristinas Vaeg 26
    Stockholm 70,   Sweden 
  • Authors:
    • Ahlsen, U
    • Montin, S
  • Publication Date: 1979

Language

  • Swedish

Media Info

  • Features: Figures; References; Tables;
  • Pagination: 42 p.

Subject/Index Terms

Filing Info

  • Accession Number: 00322158
  • Record Type: Publication
  • Source Agency: Swedish National Road and Transport Research Institute (VTI)
  • Report/Paper Numbers: CBI Forskning 5:79 Monograph
  • Files: ITRD, TRIS
  • Created Date: May 21 1981 12:00AM