Nowadays, the most common strategies employed to delay concrete degradation are related to modifications carried out during its fabrication process, such as reducing the water/cement ratio and therefore decreasing the porosity of concrete. In the case of old concrete-based structures built in the 20th Century, no particular care was given to critical parameters increasing their long-term performance, such as the water to cement ratio and the thickness of the concrete layer, because decay mechanisms were still largely unknown. One common methodology proposed for preserving concrete heritage is the use of surface treatments, especially hydrophobic agents to prevent water ingress and consolidants able to fill cracks produced by decay. In this sense, some of the new products that are being developing are based on consolidants that can directly interact with hydrated products from the OPC hydration (basically with Ca(OH)2 and C-S-H) generating new C-S-H gel. Given the interaction between these new products and those generated during the hydration of the cement paste, a deeper knowledge of how the C-S-H gel is modified after the various aging processes is vital. The present work analyzes changes in both the microstructure (porosity) of mortar (MIP), as well as changes in the C-S-H structure of the OPC paste (FTIR), after different types of physical and chemical decay processes. Experimental results indicated that the type of deterioration process highly affects the total porosity and the pore size distribution but also the mineralogy and the microstructure of the C-S-H.

Trabajo presentado al 15th International Congress on the Chemistry of Cement (ICCC), celebrado en Praga (República Checa) del 16 al 20 de septiembre de 2019.

This work has been funded by the European Union´s Horizon H2020 Research and Innovation Programme under Grant Agreement Nº760858.