Slurry of metakaolin combined with limestone addition for self-compacted concrete. Application for precast industry

Metakaolin improves the engineering properties of concrete because of its double effect on cementitious matrix (filler effect and pozzolanic properties). Moreover, metakaolin can reduce the environmental impact of concretes due to its lower carbon dioxide emission than clinker. The development of a slurry form of metakaolin opens new fields of investigations, such as its incorporation into self-compacting concretes (SCC). This study compares several SCC formulations that differ in their content of metakaolin and the form of metakaolin (powder or slurry). Limestone filler is included to study the benefit of employing ternary blended binder. As a main conclusion, the use of metakaolin, especially in slurry form, combined with limestone filler incorporation appears particularly suitable for SCC manufacture with high mechanical properties and durability, and very for the precast process optimization: it allows the mixing sequence to be shortened, while maintaining high workability, and more importantly the enhancement of strength at early age due to the particles deflocculating. The incorporation of metakaolin in slurry form appears particularly suitable to elaborate SCC and advantageous for precast product manufacturing as part of a sustainable development approach.