Title: Lowering the Clinker Factor of Limestone Calcined Clay Cements (LC3) below 50%: a Comparison with Natural Pozzolans
Author(s): Franco Zunino, Karen L. Scrivener
Publication: Symposium Paper
Appears on pages(s): 81-88
Keywords: metakaolin; reactivity; clinker factor; pozzolans; sustainability
The adoption of blended cements is the most feasible strategy to achieve a more sustainable industry. In this regard, reducing the clinker factor, while retaining performance, is the key parameter to address. Limestone calcined clays are a promising technology as they offer similar performance to OPC from 7 days onwards while enabling a reduction of the clinker content of 50%. In some regions of the world like South America, pozzolanic cements (i.e., blended cements that combine clinker with natural pozzolans) have been used for decades. Their clinker factors range from 80 down to 50%. However, their mechanical properties are in general lower as compared to OPC. In this study, we show that by using LC3-type formulations, cements with the same performance as commercial pozzolanic cements can be produced with clinker contents significantly below 50%. This is explained by the high reactivity of calcined clays and the synergetic reaction of metakaolin and limestone that allows offsetting the clinker reduction.