Multi-scale investigation of the shrinkage of alkali-activated slag

Alkali-activated slags (AAS) are promising low-carbon alternatives to ordinary Portland cement. Despite their attractive environmental and mechanical performances, their widespread adoption remains limited by their high shrinkage, which may lead to cracking and durability issues. Understanding the mechanisms governing this behavior is therefore a key challenge for the development of reliable low-carbon cementitious materials.

Shrinkage in AAS emerges from complex couplings between hydration, microstructure development, water distribution in the network, and mechanical response occurring over a wide range of spatial and temporal scales. Capturing these interactions requires combining approaches from cement chemistry, porous media physics and mechanics.

In this seminar, I will present a multi-scale investigation of shrinkage in alkali-activated slag mortars carried out during my PhD. The study follows the material from demolding to long-term aging through a combination of experimental techniques addressing several complementary aspects of the material behavior. Particular attention is given to the evolution of the degree of hydration, endogenous shrinkage, mechanical properties and water potential. These measurements provide a comprehensive description of the physicochemical state of the material throughout its evolution and allow the development of a consistent framework for interpreting deformation mechanisms.

The seminar will discuss how these different observations can be combined within a poromechanical perspective to better understand the origin of shrinkage and the role of time-dependent deformation mechanisms in alkali-activated materials.