Air void parameters

The measured specific surfaces and calculated air void spacing factors from EN 480-11 analysis of drilled cores from small blocks are shown below.

Five concretes including the two non-air entrained concretes (mix G and L) and the concrete with superabsorbing polymer (mix O) does not meet the target spacing factor of maximum 0,20. The two air entrained concretes not falling within the target range are mix A and mix D with spacing factors of 0,23 and 0,24 respectively.

It is interesting to compare the measured spacing factors to the frost resistance scaling test results performed on the same drilled cores as the air void parameter analysis. Although there is clearly not a strong correlation between the test methods it seems that a maximum requirement to the spacing factor of 0,20 mm ensures that the frost resistance performance test will result in the concrete being categorised as either "very good" or "good". However, it is strange that concretes with apparently identical air void systems such as mix A and D perform so differently in the scaling test where they are categorised as "very good" and "acceptable" respectively.