Articles, Guides & Reports

This article serves as an introduction to a series of articles on portland limestone cement (PLC) to be published in this and upcoming issues of Concrete International. Key points include PLC’s role in concrete construction and some of the associated benefits. The article also refers readers to several recent studies comparing PLC and portland cement.

This article reports on the mechanisms that allow portland limestone cement (PLC) mixtures to maintain the same levels of strength as portland cement (PC) mixtures. Mechanisms discussed include the filler effect, increased cement paste volume, heterogeneous nucleation, faster kinetics of hydration, and production of calcium carboaluminates. The performance of two PLCs produced on two different milling circuits are compared against a control PC produced on one of the same circuits.

The authors discuss the development of ternary concrete mixtures with performance characteristics that are equivalent or superior to those for a conventional concrete mixture produced with portland cement only. Mixtures included combinations of ordinary or high-early strength cement, Class C or Class F fly ash, and limestone powder. The developed ternary mixtures had about the same setting times as the conventional concrete mixture and they exhibited significantly improved measured compressive strengths and transport properties.