Recent site and laboratory studies of surface densification in high-alumina cement concrete

The occurrence of a surface densification layer in both site and laboratory-cast high-alumina cement (HAC) concretes has been studied using a combination of permeability determinations and mineralogical analyses. Such a protective ‘skin’ occurred in many of the site concretes that were examined and this has been reproduced in the laboratory in cases where a sufficiently high-temperature gradient was achieved between the concrete surface and its interior.