Concrete Placing Temperature

Concrete placing temperature is the temperature of fresh concrete at the point of placement — directly affecting setting time, strength gain, and durability. Per IS 7861:1988 + IS 456:2000 Cl. 13, the optimum range is 10-30°C; below 5°C hydration effectively stops; above 30°C causes rapid setting, excessive water demand, and shrinkage problems. For Indian sites in summer (placing temperature often >35°C), specific measures are needed.

Hot-weather concreting (placing temperature >30°C) per IS 7861: (1) Mix design adjustments — high cement content (380+ kg/m³), retarder admixture (extending workable time 60-90 minutes), reduced w/c with PCE superplasticiser. (2) Material cooling — chilled water (0-5°C), ice in mix, pre-cooled aggregate (water spray on stockpile). (3) Site practices — pre-soak forms, rebar, aggregate stockpile; cover slabs with wet hessian + plastic sheet within 30 minutes; increase ponding water depth from 25 mm to 50-75 mm; extend curing to 14 days minimum. (4) Pump retardants — additional retarder dosing for pumped concrete.

For a typical North Indian summer site (May-June, 40°C+): mix temperature targets 25-28°C achievable with chilled water + ice (replacing 25-50 kg of mix water with ice flakes lowers temperature by 5-8°C). Hot-weather concrete typically costs ₹500-1500 more per cubic metre than ordinary concrete due to admixtures and chilled water. The most-overlooked aspect of Indian summer concreting: schedule timing. Concrete placement before 10 AM or after 5 PM significantly reduces placing temperature and water demand. Many Indian sites pour at midday in summer; this systematically reduces concrete quality. Schedule planning + early morning pours essential for hot-weather concreting.