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

Abstract

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 curing on the penetrability properties of the cover region of concrete. The air permeability and sorptivity profiles indicated that curing generally affected the penetrability properties of concrete to a depth of 20 mm from the 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 the concrete. The air permeability test was more sensitive to variations in curing than the sorptivity; however, the difference between the two measured parameters was insignificant for concretes characterized by coarser pore systems (young and poorer-quality concrete). Slag concrete had higher sensitivity to inadequate curing and exhibited higher carbonation depths than plain Portland cement concrete. There was a good agreement of the air permeability and sorptivity results with the carbonation results, with the air permeability displaying better correlation.