A diffusion-reaction model for the carbonation process of oilwell cement exposed to carbonated brine under CO2 geological storage conditions is presented. The formulation consists of two main diffusion/reaction field equations for the concentrations of aqueous calcium and carbon species in the pore solution of the hardened cement paste, complemented by two diffusion-only field equations for chloride and alkalis concentrations, and by a number of chemical kinetics and chemical equilibrium equations. The volume fraction distribution of the solid constituents of the hardened cement paste and the reaction products evolve with the progress of the reaction, determining the diffusivity properties of the material. The model is used to simulate experimental tests performed by Duguid and Scherer (2010), leading to promising results indicating that the fundamental aspects of the phenomenon are captured.Peer ReviewedPostprint (author's final draft

It is well known that the Alkali-Silica Reaction (ASR) expansion in concrete is influenced by the stress state of the material. However, the extent and nature of this influence is not completely understood due to the scarcity of experimental investigation under triaxial stress states. This paper presents experimental ASR expansion curves obtained from cubical concrete specimens subjected to three different triaxial stress states, by means of a new testing machine especially designed for this purpose. The results seem to confirm that the volumetric ASR expansion rate is reduced as the applied volumetric compressive stress is increased. Additionally, there seems to be an increase of the expansion rate in the less compressed direction in detriment of the expansion rates in the most compressed ones.

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h i g h l i g h t sNew experimental setup for studying ASR expansions at aggregate-cement interfaces. ASR interfacial expansion curves of SL glass-cement interfaces are obtained. ASR products at the glass-cement interfaces are studied via SEM/EDS analyses. A reaction-expansion mechanism for ASR in SL glass concrete is proposed. The role of calcium: different swelling pressures of low-and high-Ca ASR products.

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