Reinforced Concretes of Tomorrow: Corrosion Behaviour according to Exposure Classes

Reinforced concrete is the most widely used building material but its durability in terms of concrete cover performance and corrosion of steel rebar is still a key point to be studied. To address this topic, within the frame of the national project PERFDUB, two series of eleven reinforced concrete specimens (with metric dimensions) were cast with innovative concrete mixes representative of the French experience, two shapes of rebar and two concrete covers. Then, these specimens were exposed in two natural exposure sites, one in Epernon for carbonation (XC4) and a second one in La Rochelle in the Atlantic Ocean in a tidal zone for chloride ions (XS3m). Their corrosion was carried out using non-destructive testing. In addition, in order to follow the corrosion evolution more accurately in a continuous way, two series of three specimens were casted with embedded sensors and were exposed in two other outdoor sites in Marne-la-Vallée (XC4) and in Eqiom facility (XS3e). The first results of this 20-year project in terms of corrosion of these reinforced concrete specimens obtained with laboratory and field equipment and with monitoring are presented in this paper

Screening the effect of water vapour on gas adsorption performance:application to CO₂ capture from flue gas in metal–organic frameworks

A simple laboratory-scale protocol that enables the evaluation of the effect of adsorbed water on CO2 uptake is proposed. 45 metal–organic frameworks (MOFs) were compared against reference zeolites and active carbons. It is possible to classify materials with different trends in CO2 uptake with varying amounts of pre-adsorbed water, including cases in which an increase in CO2 uptake is observed for samples with a given amount of pre-adsorbed water. Comparing loss in CO2 uptake between “wet” and “dry” samples with the Henry constant calculated from the water adsorption isotherm results in a semi-logarithmic trend for the majority of samples allowing predictions to be made. Outliers from this trend may be of particular interest and an explanation for the behaviour for each of the outliers is proposed. This thus leads to propositions for designing or choosing MOFs for CO2 capture in applications where humidity is present

Observing the Effects of Shaping on Gas Adsorption in Metal Organic Frameworks

International audienceA series of four micro- or mesoporous metal-organic frameworks [UiO-66(Zr), UiO-66(Zr)_NH2, MIL-100(Fe), MIL-127(Fe)] were synthesized in powder form and pelletized in the form of spheres by using a polyvinyl-based binder. The effect of pelletization on the adsorption of a series of gasses (N-2, CO, CO2, CH4, C2H6, C3H8, C3H6, C4H10) at 303 K was evidenced in the adsorption isotherms and the enthalpies of adsorption measured by using microcalorimetric analysis. As expected, up-takes of gas per gram of material were lower for the spheres than for the powder. However, taking into account the bulk density, this tendency was inverted, suggesting that the spherical materials are of distinct interest for gas-based applications. Nevertheless, other effects including partial pore restriction and active site "protection" may equally be evidenced for some pelletized materials, suggesting that the polyvinyl binder may play a more complex role