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[EN]: Calcium leaching is a degradation process consisting in progressive dissolution of the cement paste by migration of calcium atoms to the aggressive solution. It is therefore, a complex phenomenon involving several phases and dissolution and diffusion processes simultaneously. Along this work, a new computational scheme for the simulation of the degradation process in three dimensions was developed and tested. The toolkit was used to simulate accelerated calcium leaching by a 6M ammonium nitrate solution in cement matrices. The obtained outputs were the three dimensional representation of the matrix and the physicochemical properties of individual phases as a consequence of the degradation process. This not only makes it possible to study the evolution of such properties as a function of time but also as a function of the position within the matrix. The obtained results are in good agreement with experimental values of the elastic modulus in degraded and undegraded samples., [ES]: El lixiviado de calcio es un proceso de degradación consistente en la disolución progresiva de la pasta de cemento por la migración de los átomos de calcio a la disolución agresiva. Se trata por tanto de un fenómeno complejo que involucra simultáneamente diferentes fases y procesos de disolución y difusión. En este trabajo se desarrolló y probó una nueva herramienta computacional para la simulación del proceso de degradación en tres dimensiones. Para ello se simuló el lixiviado de calcio acelerado provocado por una disolución de nitrato amónico 6M en matrices de cemento. Como resultado se obtuvieron la representación tridimensional de la matriz y las propiedades físico-químicas sus fases a lo largo del tiempo. Esto permitió estudiar la evolución de dichas propiedades a lo largo del proceso de degradación así como en función de su posición dentro de la matriz. Los resultados obtenidos coinciden con los valores experimentales del módulo elástico tanto de muestras degradadas como intactas.

Calcium leaching is a degradation process consisting in the progressive dissolution of the paste by the migration of calcium atoms to the aggressive solution. It is therefore, a complex phenomenon involving simultaneously several crystalline phases and dissolution and diffusion processes. During this work a new program for the simulation of the degradation process in three dimensions was developed. The program decouples the transport and chemical reaction equations and solves them separately. Transport equations are solved by the Finite Element Method using an algorithm that enables the description of multi-ionic solutions on arbitrary domains. The chemical algorithm accounts for the degradation of portlandite and the CSH gel which are the main constituents of ordinary Portland cement matrices. The program was used to simulate accelerated calcium leaching by a 6M ammonium nitrate solution, in order to test it. The obtained output was a three dimensional representation of the matrix and the values calcium concentration of each particular pixel of the structure at different time steps. This not only makes possible to study the calcium to silicon ratio, porosity and elastic properties of each particular phase as a function of time but also as a function of the position within the matrix., Structural Engineering, Civil Engineering and Geosciences