As a general rule cement:lime:sand mortars give a stronger bond than plasticised mortars of a similar compressive strength.
Mortar designation (iii) is the strongest that should be used with traditional blockwork above DPC level and is generally suitable, provided structural considerations do not demand a stronger mix and the masonry is protected during construction from saturating and freezing.
Below DPC level, mortars of designation (ii) (1:1/2:4 cement:lime:sand) particularly where there is a risk of freeze/thaw, or (iii) may be used, according to soil conditions.
With the Exception of Celcon Elements, all Celcon Blocks can be used within a traditional mortar system. For information on the types of aicrete suitable for building below DPC, see Celcon Foundation Blocks and Celcon Blocks, Standard Grade.