Frequently Asked Questions

Does Auracast 50 completely eliminate the need for steam curing in precast concrete?

Auracast 50 significantly reduces or in many cases eliminates the need for steam curing by enabling the concrete to reach the required demoulding strength at ambient temperature faster than a conventional admixture. Whether steam curing can be entirely eliminated depends on the ambient temperature, the cement chemistry, the required demoulding strength, and the mould cycle time required by the production schedule. In Indian summer conditions (ambient above 25 degrees C), Auracast 50 typically enables demoulding without steam curing. In cooler North Indian winters (below 15 degrees C), some thermal curing (warm water blankets or warm curing chambers) may still be required even with Auracast 50 to achieve the required early strength. Trial mixes at the actual plant temperature should be performed before committing to a steam-free production process.

Can Auracast 50 be used in combination with fly ash or GGBS in precast mix designs?

Auracast 50 is compatible with fly ash and GGBS, but the use of these supplementary cementitious materials slows early strength development (because the pozzolanic and latent hydraulic reactions of fly ash and GGBS are slower than the primary hydration of Portland cement). This early strength retardation from fly ash or GGBS partially offsets the early strength benefit of Auracast 50. For precast applications requiring the fastest possible demoulding, minimising the replacement level of cement with supplementary cementitious materials is recommended. Silica fume, which does not retard early strength and can contribute to very early pozzolanic activity, is more compatible with Auracast 50 in early-strength precast applications.

What is the minimum cement content recommended with Auracast 50 for early strength precast?

For early-strength precast concrete applications where demoulding strength of 15 to 25 MPa is required within 12 to 16 hours, the cement content of the mix is a critical variable. A minimum cement content of 380 to 420 kg per cubic metre of OPC (or equivalent) is typically recommended as the baseline for achieving the required early strength with Auracast 50. Very low cement content mixes produce lower early strength regardless of admixture selection. Higher cement content (up to 450 to 500 kg) combined with low water-cement ratio and Auracast 50 provides the fastest early strength development for demoulding. Trial mixes should establish the optimum combination for the specific plant, cement, and production schedule.