Mix design of SCC is free to design & using single method or combination of methods has achieved universal approval and most of them have adherents. The requirements are
- Filling ability
- Passing ability
- Segregation resistance
Guidelines for the mix design
- Reducing the volume ratio of aggregate to cementitious material (1:2)
- Increasing the paste volume and water-cement ratio (w/c)
- The maximum coarse aggregate size (Normally 16 – 20 mm)
- Usage of Superplasticizer admixtures
- Viscosity enhancing admixtures
Initial mix design of SCC
- The coarse aggregate content in concrete is limited to 50% of solid volume
- The fine aggregate content in concrete is fixed to 40% of the mortar volume
- The water/powder ratio is assumed to range of 0.8-1.0,depending on the properties of the powder
The superplasticizer dosage and final water/powder ratio are determined so as to ensure self compactibility.
Testing methods of workability & typical ranges of values.
Adjustments of the mix of SCC
Laboratory trials should be used to verify properties of the initial mix composition. If necessary, adjustments to the mix composition should then be made. Once all requirements are fulfilled, the mix should be tested at full scale at the concrete plant or at site. If the performance cannot obtain, then the fundamental mix design has to be changed.