Where grout is required to provide protection to reinforcement it should have a minimum of 300kg of cement per cubic metre (AS3700, Clause 5.6).

Coarse aggregate (if used) should be no more than 10mm and preferably be rounded, to assist its flow into the cores and avoid segregation.

High walls should be grout-filled in stages to avoid “blow-outs” from hydrostatic pressure. For example, a 3m high wall of 190mm thick blocks should be filled in 2 lifts of 1.5m.