Combination cements are produced at the concrete batching plant where the two powders are combined in accordance with standardised procedures.
The choice of the most appropriate type of cement will be dictated by:
- Availability - batching plant may stock only one type of addition
- Ambient temperature (winter/summer) - different cements give differing concrete setting characteristics, which are sensitive to temperature.
- Setting Time - Window available for completing the power finishing.
- Strength development - early strength improves the tensile strain capacity and reduces the risk of cracking.
It is recommended for floors that, in normal circumstances, the percentage of fa and ggbs should be limited to 30% and 35% respectively. The limiting level of the addition must be specified.