Study of the recycled aggregates nature’s influence on the aggregate–cement paste interface and ITZ

Today it is highly recognized that the structure of the cement paste matrix close to the aggregates, is different from the rest of the cement paste. This investigation compares the possible interfacial transition zone (ITZ) formation by means of the nanoindentation test and Scanning Electron Microscopy (SEM), with aggregate inclusions of three different natures: limestone (NA), recycled concrete aggregate (RCA) and recycled ceramic aggregate (RC). This study demonstrated that nature of the aggregate and the w/c ratio conditions determines the micro structural characteristics of the aggregate–cement paste interface and the mechanical properties of the ITZ.