Geo-Congress 2020
Application of Fly Ash to Improve the Mechanical Properties of Paste Tailings
Publication: Geo-Congress 2020: Geotechnical Earthquake Engineering and Special Topics (GSP 318)
ABSTRACT
Fly ash (FA) as supplementary cementing material (SCM) or a single binder agent can have two potential applications in mining. In this study the application of class C fly ash both as a single binder agent to improve the mechanical properties of tailings at the paste consistency and as an SCM to substitute Portland cement (PC) in cemented paste backfill (CPB) was evaluated through unconfined compressive strength (UCS) testing. Gold mine tailings were mixed with PC and/or class C fly ash at the initial solid content of 78%. Specimens were prepared by mixing tailings with 3% PC, 1.5% PC:1.5% FA, 1.5% PC:3% FA, and 7% FA binder contents and cured for 90 days maximum. The specimens with 3% PC and 1.5% PC:3% FA binder contents yielded fairly similar 90-day UCS values. The specimen with 7% FA binder content yielded a 90-day UCS value of 109 kPa. Vicat needle tests were performed to investigate the impact of PC replacement with fly ash in CPB on the initial and final setting times. The replacement of 50% PC with class C fly ash resulted in approximately 3.5 times longer initial and final setting times. Based on the test results class C fly ash can be successfully used to develop the most economical CPB mix design; however, longer setting time is needed. Moreover, the test results indicate a potential application of class C fly ash to be used as a single or major binder content to improve the mechanical properties of tailings at the paste consistency.
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ACKNOWLEDGMENT
This study is sponsored by Golder Associates Inc. Their support is gratefully acknowledged.
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Information & Authors
Information
Published In
Geo-Congress 2020: Geotechnical Earthquake Engineering and Special Topics (GSP 318)
Pages: 890 - 897
Editors: James P. Hambleton, Ph.D., Northwestern University, Roman Makhnenko, Ph.D., University of Illinois at Urbana-Champaign, and Aaron S. Budge, Ph.D., Minnesota State University, Mankato
ISBN (Online): 978-0-7844-8281-0
Copyright
© 2020 American Society of Civil Engineers.
History
Published online: Feb 21, 2020
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