Speaker
Description
This presentation explores the chemo mechanical behavior of heterogeneous porous materials, with particular attention to how reaction kinetics interact with pore system characteristics. Mortars serve as a representative example of such materials due to their inherently heterogeneous pore structure.
The study focuses on delayed ettringite formation (DEF), a degradation mechanism in cement based materials in which ettringite forms after hydration, using sulfate sources already present within the material. To investigate this phenomenon, an experimental program was designed to monitor changes in sample length, ettringite content, and evolution of pore structure across a range of mortar mixtures with different sand to binder ratios.
The findings indicate that pore size distribution plays a decisive role in reaction kinetics. Larger pores tend to act as the primary sites for ettringite precipitation, while finer pores control the transport of ions that drive the reaction. This interplay not only governs the progression of DEF but also modifies the pore size distribution of the material as the reaction proceeds.
Because the initial pore structure depends strongly on the size, quantity, and distribution of aggregates and sand, materials with identical sand to binder ratios can still exhibit substantially different reaction behaviors. This highlights the importance of considering pore system heterogeneity when assessing the susceptibility of mortars to DEF and similar chemo mechanical processes.
| Country | Belgium |
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