Structural concrete with recycled aggregate: advances in mechanical properties, durability and sustainability

A large number of tests has been carried out in the last 15 years all around the world to study the possibility to use recycled concrete aggregates (RCA) to produce structural concrete. Earlier tests indicated that RCA concrete had lower properties in comparison to ordinary concrete, such as lower elastic modulus, a more brittle post-elastic behavior, lower workability, higher shrinkage and creep. Most of these issues have been addressed to the content of cement mortar remaining in adhesion to the aggregate after the recycling processes and that cannot be totally eliminated without high economic and ecological costs. This cement mortar which has undergone the crushing process creates zones of weakness in the RCA, causes higher water absorption, higher concrete porosity and causes the decay of the aforementioned properties. More recent tests prove that Recycled Concrete shows this peculiar problems only with a percentage of substitution of standard aggregates with RCA higher than 30%. Under this percentage recycled aggregate concrete (RAC) can be considered as a standard concrete, on condition that an appropriate mix design is performed

Identifying the Importance of Disaster Resilience Dimensions across Different Countries Using the Delphi Method

Supplementary Materials: The following are available online at https://www.mdpi.com/article/10.3390/su14159162/s1, Figure S1: Results of the internal cluster validity indices, S8: Survey used in the Delphi process, Table S1: Countries selected in the research, Table S2: Imputation of missing values: identification of the nearest neighbors, geographical meaningfulness, and availability of data, Table S3: Clusters of countries considering 3 clusters, Table S4: Clusters of countries considering 4 clusters, Table S5. Clusters of countries considering 5 clusters, Table S6: Clusters of countries considering 6 clusters, Table S7: First structure of the proposed DRI, Table S8: Average scores (sc) and normalized weights (w) of the Social sub-dimensions by cluster, Table S9: Average scores (sc) and normalized weights (w) of the Economic sub-dimensions by cluster, Table S10: Average scores (sc) and normalized weights (w) of the Environmental sub-dimensions by cluster, Table S11: Average scores (sc) and normalized weights (w) of the Habitat sub-dimensions by cluster, Table S12: Average scores (sc) and normalized weights (w) of the Infrastructure sub-dimensions by cluster, Table S13: Average scores (sc) and normalized weights (w) of the Institutional sub-dimensions by cluster.Informed Consent Statement: Informed consent of the participants was waived according to a Statement from the Ethics Committee of the Centre for Social Studies (CE-CES).The article proposes a framework establishing a disaster resilience index applicable worldwide that accounts for differences between countries in terms of development and in terms of the relevance of several resilience dimensions. To achieve this index, countries were clustered using an indicator that reflected their performance according to the Sustainable Development Goals. For each cluster of countries, a Delphi process was used to obtain scores for every resilience dimension and sub-dimension that were then transformed into weights that varied from cluster to cluster to reflect differences in sustainable development. The article discusses the methodology that led to the quantification of the weights according to the Delphi process, as well as its results. The results highlighted the anticipated differences between different groups of countries, but also reflected cluster-specific features that should be accounted for when analyzing disaster resilience. The article also discusses different applications and possible improvements of the proposed framework based on comments collected during the Delphi process