Quicklime and Calcium Sulfoaluminate Cement Used as Mineral Accelerators to Improve the Properties of Cemented Paste Backfill with a High Volume of Fly Ash

• Main Authors: Hangxing Ding, Shiyu Zhang
• Format: Article
• Language: English
• Published: MDPI AG 2020-09-01
• Series: Materials
• Subjects: calcium sulfoaluminate cement; quicklime; fly ash; hydration evolution; CO₂ emission
• Online Access: https://www.mdpi.com/1996-1944/13/18/4018

In order to reduce the CO₂ emission and cost of binders used in cemented paste backfill (CPB) technology, new blended binders with a large amount of fly ash (FA) were fabricated. Different doses of quicklime and calcium sulfoaluminate cement (CṠA) were used as mineral accelerators to improve the early workability of CPB. The effects of CṠA and quicklime on flowability, compressive strength, pore structure, hydration heat, and hydration evolution were investigated experimentally. The results showed that the addition of quicklime and CṠA reduced the spread diameter of the fresh backfill and improved the mechanical performance of the hardened CPB. With increasing quicklime and CṠA, the cumulative hydration heat of the blended binder distinctly increased in the first 6 h. CṠA improved the initial hydration by increasing the reactivity, and quicklime increased the hydration rate by activating FA. The blended binder (15% quicklime + 10% CṠA) with the lowest CO₂ emission and cost had potential application in filling technology.