No abstract

No abstract

The microstructural effects of exposure to a 15% magnesium sulphate, 15% sodium sulphate, and mixed solutions were observed in mortars with and without silica fume, using the non-destructive impedance spectroscopy technique. The non-destructive "Wenner" resistivity test and the classical mercury intrusion porosimetry were used as contrast techniques. The compressive strength of the mortars was also studied. In view of the results obtained, impedance spectroscopy was the most sensitive technique for detecting changes in the porous network of the studied mortars. The addition of silica fume results in a more refined microstructure and a higher compressive strength in mortars exposed to aggressive sulphate solutions.

No abstract

No abstract

No abstract

At present, one of the most suitable ways to get a more sustainable cement industry is to reduce the CO2 emissions generated during cement production. In order to reach that goal, the use of ground granulated blast-furnace slag as clinker replacement is becoming increasingly popular. Although the effects of this addition in the properties of cementitious materials are influenced by their hardening conditions, there are not too many experimental studies in which slag concretes have been exposed to real in situ environments. Then, the main objective of this research is to study the short-term effects of exposure to real Mediterranean climate environment of an urban site, where the action of airborne chlorides from sea water and the presence of CO2 are combined, in the microstructure and service properties of a commercial slag cement concrete, compared to ordinary Portland cement (OPC). The microstructure was studied with mercury intrusion porosimetry. The effective porosity, capillary suction coefficient, chloride migration coefficient, carbonation front depth, and compressive strength were also analyzed. Considering the results obtained, slag concretes exposed to a real in situ Mediterranean climate environment show good service properties in the short-term (180 days), in comparison with OPC.

In this study, we applied potentiodynamic polarization to the analysis of surface corrosion in a 2017‐T4 alloy during a stress corrosion cracking (SCC) test in 1 m NaCl solution. A constant load SCC test was chosen, classifying the applied load into three categories – no load, medium load, and high load – with the material's yield strength as a maximum load. Electrochemical measurements carried out during the SCC test allowed us, by plotting the current density versus the applied potential on a logarithmic scale, to determine the electrochemical characteristic parameters for each load category. These parameters, combined with both cross‐sectional and surface morphological analysis, were used to qualitatively characterize the corrosion of the aluminum alloy. All tests performed revealed two different attack behaviors, one characterized by shallow pits and the other by a deep, intergranular penetration. The presence of each behavior depends on the intensity of the applied load, which involves variations in the polarization curve and therefore modifies the electrochemical parameters. Copyright © 2016 John Wiley & Sons, Ltd.