Novel micro fillers and classification methods to enhance the performance of technical mortars

 
Several fines such as Ground Calcium Carbonate (GCC), fly ash (FA) and blast furnace slag (BFS) have been used for many years as fillers or additions to enhance performance/cost of normal concrete. For Very High Performance Concrete (VHPC) and Ultra High Performance Concrete (UHPC) many studies have shown that other microfiller apart from silica fume can be used. It is well known that GCC microfiller (D50<5?m) improves packing of the cement granular skeleton and acts as the crystallisation nucleus for the precipitation of portlandite. These simultaneous effects accelerate the hydration of cement grains, particularly with lower D50 and a lower water/cement ratio. Another promising idea, pointed out by many authors is to use several additions or microfillers together to optimise fluidity and compressive strength of VHPC. Thus there is a need to find a new predictive tool to compare the behaviour of the different microfillers (FH) in the concrete. The aim of this paper is to present the LG16 test method based on a specific concrete equivalent mortar (CEM) to evaluate the microfiller (FH) effect on the fluidity, viscosity, admixture need, setting time and strength of the final concrete. Four different calcium carbonate microfillers were evaluated with the LG16 test method. Results show that the new Fine-GCC is the most valuable product.