Investigations into Properties of Collie Fly Ash that Influence Admixture Sensitivity in Blended Cement Concretes

The construction of concrete slabs-on-ground in Australia requires often requires good control of setting times and bleeding rates in lean concretes using air entraining admixtures to minimize the potential for plastic cracking. While this has been successfully achieved on the east coast of Australia for decades with fly ash concretes a new source of fly ash from the Collie power station located on the west coat of Australia proved difficult to use. The University of New South Wales undertook an investigation into the cause of sensitivity and variability exhibited by key properties of concretes that contained Collie fly ash. Testing of the basic properties of three Collie fly ash samples and one sample of fly ash from Eraring power station was used to characterize the materials and the samples separated into specific size fractions with further testing undertaken. Testing undertaken included LOI, density, color, fineness, carbon content, sulfur content, and physical features using SEM. The investigation concluded that the causes of the admixture sensitive behavior of Collie fly ash concrete is not simply due to the presence of carbon but the high surface area and low density of these carbon particles in association with the presence of oxidizable sulfur components.

Language

  • English

Media Info

  • Media Type: Print
  • Features: Figures; Photos; References; Tables;
  • Pagination: pp 149-164
  • Monograph Title: Ninth CANMET/ACI International Conference on Fly Ash, Silica Fume, Slag and Natural Pozzolans in Concrete

Subject/Index Terms

Filing Info

  • Accession Number: 01053785
  • Record Type: Publication
  • ISBN: 139780870312410
  • Report/Paper Numbers: SP-242-12
  • Files: TRIS
  • Created Date: Jul 16 2007 12:56PM