Air permeability versus sorptivity: effects of field curing on cover concrete after one year of field exposure

There is substantial interest in the air permeability and sorptivity tests as potential indicators of concrete quality. This paper reports on part of a research programme that investigated the effects of field exposure and cu ring on the penetrability properties of the cover region of concrete. The a ir permeability and sorptivity profiles indicated that curing generally aff ected the penetrability properties of concrete to a depth of 20 mm fi-om th e exposed surface, however the curing-affected zone varied widely depending on concrete type and strength as well as exposure conditions. Curing with wet hessian improved the penetrability properties of the cover region of th e concrete. The air permeability test was more sensitive to variations in c uring than the sorptivity; however; the difference between the two measured parameters was insignificant for concretes characterized by coarser pore s ystems (young and poorer-quality concrete). Slag concrete had higher sensit ivity to inadequate curing and exhibited higher carbonation depths than pla in Portland cement concrete. There was a good agreement of the air permeabi lity and sorptivity results with the carbonation results, with the air perm eability displaying better correlation.