Mass Concrete Temperature Calculator
Placement temperature, adiabatic rise and peak temperature in one step.
Inputs
Result
Formula
| T0 = Σ(mi·ti) / Σmi | weighted by mass |
| Th = mce·Q / (c·ρ) | c = 0.97, ρ = 2400 |
| Tmax = T0 + Th·k | k = 0.60 / 0.75 / 0.85 by thickness |
| surface ≥ Tmax − 25 ℃ | differential control |
Cement 300 kg at 40 ℃, sand 700 at 30 ℃, gravel 1150 at 28 ℃, water 170 at 15 ℃: placement temperature 29.2 ℃; with Q = 335 kJ/kg the adiabatic rise is 43.2 ℃; at 1-2 m thickness k = 0.75 gives 32.4 ℃ of real rise and a 61.6 ℃ peak, so the surface must stay above 36.6 ℃.
FAQ
Does cement temperature really matter that much?
Yes. Bulk cement straight from a tanker can be 70-80 ℃ in summer while aggregate sits near 30 ℃. Cement is only about 13% of the mass but 50 ℃ hotter, contributing 6-7 ℃ to placement temperature - the easiest item to overlook. Dropping cement from 75 to 45 ℃ cuts placement temperature by about 4 ℃, far more effective than wetting aggregate.
What is the difference between adiabatic and actual rise?
Adiabatic rise assumes no heat loss at all - an upper bound. Real elements lose heat to air and ground, so a factor below 1 applies. Thin sections dissipate far more: a 1 m wall may reach only 60% of the adiabatic value, while a 3 m raft exceeds 85% and behaves almost adiabatically. That is why mass concrete is defined by minimum dimension over 1 m, not by volume.
Why the 25 ℃ core-surface limit?
Differential temperature creates thermal stress: the core expands while the surface is held back, putting the surface in tension when its tensile strength is still low. A 25 ℃ differential corresponds to roughly 1 MPa of surface tension, close to early-age capacity. Beyond that, surface cracks form and later become paths for water and chloride. The point is not cooling, it is narrowing the differential.
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Results are estimating aids only and are not a design basis. Construction and final accounts must follow the drawings, the applicable standards and an approved method statement. Anything affecting structural safety, shoring or falsework must be checked by a suitably qualified engineer.