Investigation of the moisture influence on permeation properties of alkali-activated slag concrete

This study reports an experimental investigation designed to assess the influence of near- surface moisture contents on permeation properties of alkali-activated slag concrete (AASC). Three AASC and normal concretes with compressive strength grades ranging from C30 to C60 were tested under five different drying periods. Assessment of moisture distribution was achieved using 100 mm diameter cores with drilled cavities. Results indicate that air permeability of AASC is very sensitive to the moisture content and its spatial distribution, especially at relative humidity above 65%. To control the influence of moisture on permeation testing, the recommendation of this paper is that AASC specimens should be dried in controlled conditions at 40 oC for 10 days prior to testing. It was also concluded from this study that AASC tends to perform less well, in terms of air permeability and sorptivity, than normal concrete for a given strength grade. This conclusion reinforces the need to further examine AASC properties prior to its widespread practical use.