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.