POZZOLANIC PROPERTIES OF REJECT FLY ASH IN BLENDED CEMENT PASTES

A significant portion of the pulverized fuel ash produced from coal-fired power plants is rejected from the ash classifying process. This reject fly ash (r-FA) has high carbon content and large particle size, but it may be appropriate for certain uses which require relatively lower strength and reactivity, such as in solidification and stabilization processes of hazardous waste and materials for road base or subbase construction. This paper investigates the properties of r-FA and explores its possible applications. Experimental results are presented from a study on the mechanical and hydration properties of cementitious materials prepared by blending r-FA with ordinary Portland cement. Parallel mixes were also prepared with fine fly ash (f-FA) for comparison. Selective chemical activators were added to the mix to study the effects of the activators on the properties of the blend system. The results show that r-FA generally has a lower rate of hydration than f-FA, particularly at the early stage of hydration. Adding calcium hydroxide alone had little effect on accelerating the hydration of r-FA, but adding a small quantity of sodium sulfate or potassium sulfate together with calcium hydroxide significantly accelerated the hydration reaction. Findings also suggested that a higher but not excessive water to binder ratio benefited the reaction of r-FA. The results of the compressive strength measurement correlated nicely with the degree of hydration results.

• Availability:
  • Find a library where document is available. Order URL: http://worldcat.org/issn/00088846
• Supplemental Notes:
  • Page range: pp 1857-1865.
• Corporate Authors:

  Elsevier

  The Boulevard, Langford Lane
  Kidlington, Oxford  United Kingdom  OX5 1GB
• Authors:
  • Poon, C S
  • Qiao, X C
  • Lin, Z S
• Publication Date: 2003-11

Language

• English

Media Info

• Features: Figures; References; Tables;
• Pagination: 9 p.
• Serial:
  • Cement and Concrete Research
  • Volume: 33
  • Issue Number: 11
  • Publisher: Elsevier
  • ISSN: 0008-8846
  • Serial URL: http://www.sciencedirect.com/science/journal/00088846

Subject/Index Terms

• TRT Terms: Activation (Chemistry); Calcium hydroxide; Cement additives; Cement paste; Chemical reactions; Compressive strength; Fly ash; Hydration; Mechanical properties; Mix design; Portland cement; Pozzolan; Sodium sulfate
• Uncontrolled Terms: Potassium sulfate
• Subject Areas: Highways; Materials; I32: Concrete;

Filing Info

• Accession Number: 00983825
• Record Type: Publication
• Files: TRIS
• Created Date: Dec 29 2004 12:00AM