Laurent Frouin

Microstructural analysis of RPC (Reactive Powder Concrete)

Reactive Powder Concretes (RPC) are characterized by high silica fume content and very low water to cement ratio. Granulometry and heat treatment were optimized to obtain excellent mechanical and durability properties. The study of several RPC compositions by Mercury Porosimetry, Thermogravimetric Analysis and X-ray diffraction made it possible to better understand their microstructural properties depending on their heat treatment. Influence of temperature on hydration and pozzolanic reaction were examined. For high temperature, the presence of a crystal hydrate, xonotlite, was observed. Mercury Porosimetry also showed that a minimum porosity could be obtained with selected heat treatment.

Microstructure and mechanical properties of macrodefect-free cements

The mechanical properties of macro-defect-free cements were investigated with the help of fracture mechanics and rheology; transmission electronic microscopy (TEM) and scanning electronic microscopy (SEM) were used to characterize the microstructure. The microstructure was found to consist of nanosized hydration products embedded in a cross-linked polymer matrix. The nanoscale composite structure of the cement is thought to play an important part in the mechanical properties.