Properties of fresh concrete containing large amounts of fly ash

✍ Scribed by Dan Ravina; P.K. Mehta

• Publisher: Elsevier Science
• Year: 1986
• Tongue: English
• Weight: 660 KB
• Volume: 16
• Category: Article
• ISSN: 0008-8846
• DOI: 10.1016/0008-8846(86)90139-0

✦ Synopsis

The effect of replacing 35 to 50 percent of cement by fly ash on workability, water requirement, bleeding, and setting time of lean concrete mixtures was investigated, using two ASTM Class F and two ASTM Class C fly ashes.

Workability of all concrete mixtures containing fly ash was found to be better than that of the control mixtures (without fly ash).

The water requirement for obtaining the designated slump (2 in., 5cm) of all concrete mixtures containing fly ash was reduced by 5 to i0 percent. The rate and volume of the bleeding water was either higher or about the same compared with the control mixture, depending on the type of fly ash and the mix proportions.

Setting time was delayed for both fly ash types and at all levels of fly ash substitution compared with the control mixture; initial setting time was delayed from 20 min up to 4 hrs and 20 min, and the final setting time from 1 hour up to 5 hrs and 15 min, depending on the type and the amount of fly ash used.