# Mass Concrete Temperature Calculator

Placement temperature, adiabatic rise and peak temperature in one step.

- Page: https://jianzhujisuan.com/en/concrete-temp-control
- Category: Concrete (https://jianzhujisuan.com/en/c/concrete)
- Chinese version: https://jianzhujisuan.com/zh/concrete-temp-control.md
- Data checked: 2026-10-25

## Quick result

With the default inputs (Cement 300 kg/m³, Cement temp 40 ℃, Sand 700 kg/m³, Sand temp 30 ℃, Gravel 1150 kg/m³, Gravel temp 28 ℃, Water 170 kg/m³, Water temp 15 ℃, 7-day heat of hydration Q 335 kJ/kg, Pour thickness 1.0-2.0 m (k = 0.75)): **Expected peak core temperature 61.6 ℃**

## Inputs

| Parameter | Type | Default | Unit | Note |
|---|---|---|---|---|
| Cement | number | 300 | kg/m³ |  |
| Cement temp | number | 40 | ℃ |  |
| Sand | number | 700 | kg/m³ |  |
| Sand temp | number | 30 | ℃ |  |
| Gravel | number | 1150 | kg/m³ |  |
| Gravel temp | number | 28 | ℃ |  |
| Water | number | 170 | kg/m³ |  |
| Water temp | number | 15 | ℃ |  |
| 7-day heat of hydration Q | number | 335 | kJ/kg |  |
| Pour thickness | select | 1.0-2.0 m (k = 0.75) | — |  |

## 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

## Worked example

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 ℃.

## Questions

### 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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