27/06/2026
🌡️ Above 30 °C, your concrete is working against you.
Hydration doubles in speed. Working time shrinks by up to 50 %. Slump drops during transit and what looks like a workability problem on arrival is already a quality issue in the making.
Adding water to the truck is NOT the answer. ACI 305.1 and EN 206 explicitly prohibit exceeding the specified w/c ratio to recover slump loss. Every unauthorised litre permanently reduces strength and increases permeability.
What the norms recommend instead:
→ If possible: postpone. ACI 305R-20 names rescheduling as the most effective measure.
→ If the pour must go ahead: precool mix water, shade aggregates, use retarding admixtures, pour at night or early morning, pre-wet subgrade and formwork.
Even with all of that in place, hot weather compresses your margin across multiple failure modes at once. Real-time monitoring — temperature/maturity, formwork pressure, compaction, and w/c ratio at discharge — is what turns assumption into documented fact.
🔗 https://vemaventuri.io/concrete-monitoring-solution-finder
