PREDICTING THE LONG-TERM PERFORMANCE OF STRUCTURES MADE WITH ADVANCED CEMENT BASED MATERIALS IN EXTREMELY AGGRESSIVE ENVIRONMENTS: CURRENT STATE OF PRACTICE AND RESEARCH NEEDS – THE APPROACH OF H2020 PROJECT RESHEALIENCE.

Recently, in the framework of H2020, the European Commission has funded the project ReSHEALience (www.uhdc.eu), whose main goal is to develop an Ultra High Durability Concrete (UHDC) and a Durability Assessment-based Design (DAD) methodology for structures, to improve durability and predict their long-term performance under Extremely Aggressive Exposures. The project, coordinated by Politecnico di Milano, gathers 14 partners from 8 different countries (Italy, Spain, Estonia, Germany, Greece, Ireland, Israel, Malta), including 6 academic and research institutions together with 8 industrial partners, which cover the whole value chain, from producers of concrete constituents to construction companies to stake-holders and end-users. A key activity of the project will consist in the development of a theoretical model to evaluate ageing and degradation of UHDC structures, extending the modelling to predict the lifespan, and its incorporation in a Durability Assessment-based Design (DAD) methodology, which will be validated against experimental tests performed in the same project and the monitored performance of six full-scale pilots in real exposure conditions. The paper, starting from a review of the current state of art on the modelling of advanced cement based materials in extremely aggressive environments (EAE), will address the approach pursued in the project

The effect of the capillary forces on the desorption of hydrogels in contact with a porous cementitious material

This paper examines the desorption of hydrogels in contact with porous cementitious materials to aid in understanding the mechanisms of water release from superabsorbent polymers (SAP) into cementitious materials. The dependence of hydrogel desorption on the microstructure of cementitious materials and relative humidity was studied. It was shown that the capillary adhesion developed at the interface between the hydrogel and cementitious materials increased the desorption of the hydrogels. The size of hydrogels was shown to influence desorption, beyond the known size dependence of bulk diffusion, through debonding from the cementitious matrix, thereby decreasing the effect of the Laplace pressure on desorption. Microscopic examination highlighted a stark contrast in the desorption morphology of hydrogels with different chemical compositions