Chemo-Mechanical AGIng of Cementitious materials (MAGIC)

'What'

MAGIC aims to: 
•    quantify the chemo-mechanical multi-scale evolution of cementitious materials under the chemical degradation expected in repository environments. To identify the main reactive pathways at the repository scale during the re-saturation phase and at the saturated conditions.  
•    obtain a reference chemo-mechanical model of Portland and low-pH concrete exposed to relevant disposal environments, considering representative boundary conditions. 
•    estimate the extent of the impact of microbial activity on concrete properties (low-pH and Portland cement) in partially and fully saturated media.
 

'Why'

Nowadays, most of the experimental data are limited to the short-term material evolution and the long-term mechanical integrity of the cementitious material remains largely unknown. Following knowledge gaps have been identified:

•    What is the impact of various chemical degradation phenomena on the mechanical behavior of massive cementitious materials?
•    What is the impact of microbially induced processes in the chemo-mechanical behavior of cementitious materials? Do these processes change the chemical evolution which is expected to occur without microbiological activity?
•    How to model the long-term mechanical behavior of cementitious materials during hydraulic transients or fully saturated media with respect to the chemical evolution with and without microbial activity? 
•    How to achieve a comprehensive model based description of the multi-scale modelling process?  
 

Closing words from WP Leader

The last year aimed at consolidating all the key and noteworthy results achieved by the partners working over the past three years in the work package. One deliverable, the final SOTA, is the result of the analysis of five deliverables containing the entirety of the detailed scientific production of the WP. While MAGIC has been structured into tasks depending on the scale at which the chemo-mechanical ageing of cementitious materials in a geological disposal environment was studied, an important work in term of synthesis was done these last months, to provide a different perspective. Indeed, we have crossed reference all the results from all tasks with a contextualization related to the life cycle to which the concretes will be exposed: from the operational phase to the long-term phase. The scientific results allow to fill several gaps initially identified and the synthesis in the final SOTA allows the reader both to recall the objectives of MAGIC motivated by the state of the art at the beginning of the project and to quickly understand the studies conducted with a systematic and concise recall of the experimental or modelling conditions chosen and a focussed description of the noteworthy results. For more details, the reader is referred to the technical deliverables published by MAGIC. The set of deliverables highlights the knowledge development of the MAGIC WP on the chemo-mechanical ageing of cementitious materials in geological disposal conditionsincluding the operational and long-term phases; the impact of microbial activity; the improvement of multi-scale modelling, particularly the chemomechanical modelling at the structural scale. Overall, MAGIC can be considered a success for most of the objectives set, although a number of points obviously remain to be studied in greater depth, in particular the long-term evolution of the bacterial impact on concrete, and above all taking into account the complex chemistry at the scale of the structures for longterm chemo-mechanical modelling, including neural network approaches.