External Sulfate Attacks (ESA) – A chemo-mechanical degradation that undermines the structural integrity and safety of concrete structures.
The presence of sulfate in groundwater is of great concern since it affects the durability of cement-based materials or cement treated-soil, a technique increasingly employed to use soil in situ in order to reduce CO2 emission impact. The range of structures affected by this is wide since it covers foundation concretes, tunnels, treated backfill. The mechanism causing the sulfate to propagate into the porous media changes the chemical composition of the initial pore solution, disturbing the local thermodynamic equilibrium, dissolution and precipitation reactions. A substantial chemical and mechanical degradation may lead to expansion, cracks, decohesion and finally to a destruction of the cementitious matrix. The position will focus on the mineral and ionic species evolutions due to ESA undertaken from a chemo-transport point of view with advanced chemical codes. A deeper understanding of the processes that take place during sulfate interaction will be pursued. For this, models need to be evaluated on their ability to simulate the decalcification of C-S-H and ettringite precipitation at critical locations, especially for cementitious materials with new additions. Furthermore, a coupled approach able to estimate mechanical degradation will be employed to explain such a complex mechanism.
More information and contact details in the announcement (PDF) in the Downloads section.
Véronique Baroghel-Bouny from FM2D at Gustave Eiffel University
Anthony Soive from GeoCod research team at Cerema (Anthony Soive on ResearchGate)
Eddie Koenders from The Institute of Construction and Building Materials at the Technical University of Darmstadt