Influence of Powder Activated Carbon (PAC) in Fly Ash on the Properties of Concrete

Class C Fly Ash (CFA) is routinely used by contractors as a partial replacement of Ordinary Portland Cement to produce concrete. However, the Arkansas Department of Transportation (ArDOT) is concerned about certain CFAs as they contain powder activated carbon (PAC). The main objective of this study is to assess the influence of PAC in fly ash on the properties of concrete. Specifically, it will develop guidelines controlling the PAC in fly ash to be used in concrete. This will be accomplished through a comprehensive review of available literature and experience of other states, and extensive laboratory testing of selected fly ashes. Fly ash samples will be collected in consultation with ArDOT engineers, ready-mix contractors, and fly ash suppliers. Fresh concrete will be prepared in the laboratory to determine air-content. Hardened concrete will be tested for expansion properties. Data collected from laboratory tests will be analyzed and summarized to provide implementation recommendations to ArDOT. This study will quantify the increase in demand of the air-entraining agent (AEA) in producing durable concrete. A higher amount of large entrained air bubbles due to the addition of fly ash can lead to the reduction in the volume of the entrained air bubbles during the service life of the concrete. Furthermore, the spherical shape of fly ash is found to cause a larger rate of reduction in the volume of the entrained air bubbles as the coalescence and escape of entrained air bubbles can easily occur. The degree of coalescence of air bubbles can be reduced by careful selection of the AEA and the mixing procedure. Alternatively, the unburned carbon can be reduced or removed by a high-temperature burnout or separated physically. To separate carbon from ash, additional steps such as froth flotation process can be adopted. Such knowledge and techniques do not exist in the public domain today. The current study aims to reduce this knowledge gap.

Language

  • English

Project

  • Status: Active
  • Funding: $77000
  • Contract Numbers:

    19CASU03

  • Sponsor Organizations:

    Office of the Assistant Secretary for Research and Technology

    University Transportation Centers Program
    Department of Transportation
    Washington, DC  United States  20590
  • Managing Organizations:

    Transportation Consortium of South-Central States

    Louisiana State University
    Baton Rouge, LA  United States  70803
  • Project Managers:

    Melson, Christopher

  • Performing Organizations:

    Arkansas State University

    Department of Engineering
    P.O. Box 1740
    State University, AR  United States  72467
  • Principal Investigators:

    Hossain, Zahid

  • Start Date: 20190815
  • Expected Completion Date: 20210215
  • Actual Completion Date: 0
  • USDOT Program: University Transportation Centers Program

Subject/Index Terms

Filing Info

  • Accession Number: 01713208
  • Record Type: Research project
  • Source Agency: Transportation Consortium of South-Central States
  • Contract Numbers: 19CASU03
  • Files: UTC, RiP
  • Created Date: Aug 1 2019 4:19PM