Editorial

More and more the effect of mineral additions on the properties of concrete are studied from a microstructural point of view. In the present issue of Advances in Cement Research, four of the six papers deal with the different aspects of the impact of the presence of several kinds of additions on the concrete performance.\n\nThe first four papers address the research from new perspectives and highlight the key aspects which influence the changes detected in the performance. This approach is much needed because it is necessary to pass from the empirical registering of the changes produced by the additions, to the ability to design the future concrete mixes from the identified key basic parameters and the proportions of mineral additions to the cement.\n\nOver the years, in several countries, the additions were considered as a waste material whose valorisation appears from an environmental point of view when added to the ordinary Portland cement. However, at present, their benefits appear mainly from the durability point of view and are increasingly recognised and appreciated. These benefits are particularly important with respect to retarding the chloride ingress into the concrete and, although the effect is not so beneficial in the case of carbonation, the possibility to lower the w/c ratio makes the additions a valuable raw material for extending the service life of reinforcements.\n\nFurthermore, confidence in their potential benefits is promoting the search for sources of subproducts of different industries that, with adequate treatment, could be compatible with the cement. Three of the papers of the present issue are related to these kinds of industrial subproducts (rice husk, paper sludge or gel waste–clay–limestone) and exploring their impact into the resistance to leaching through the pozzolanic activity they exhibit, or to the changes they introduce into the microstructure of the hydrated cement paste.