Concrete @ your Fingertips


Entrained air - BS 8500 requirements

The minimum specified entained air content depends on the maximum aggreate size and, since the publication of BS 8500-1:2015, the exposure classification. See table below.

Note that designated concrete PAV1 can be used for XF1, XF2 and XF3 exposure classes. Designated concrete PAV2 is suitable for all XF exposure classes. The limiting constituent proportions for PAV1 and PAV2 are typically more onerous than those required for designed concretes to cover a range of exposure condiitons.

Min. specified air
content %

Max. aggregate
size (mm)

XF1 to XF4, PAV 1, PAV 2

Max. allowable deviation
on range limit %

40              4.0 -0.5, +5.0
20              4.5 -0.5, +5.0
14              5.5 -0.5, +5.0
10              6.5 -0.5, +5.0

Also note that the BS 8500: 2015 Table A.9 Note c) states that cements or combinations containing more than a mass fraction 55% ground granulated blastfurnace slag (ggbs) might not be suitable for the wearing surfaces of pavement concrete due to the possibility of surface scaling in the top few milimeters.


Acknowledgement: The Concrete Society