How the Log Is Built
Readings every [early interval] h for the first 72 h, then every [later interval] h
Minimum ACI 306 temperature for the least section dimension
Mass concrete sections ≥ 0.9 m: max 70 °C, core–surface difference ≤ 19 °CWorked Example
250 mm slab, finished 14:00 Monday 2 November 2026, every 4 h for 72 h then every 12 h, for 7 days:
- 27 readings: 14:00, 18:00, 22:00, 02:00, 06:00 … then twice a day
- Keep the concrete at or above 13 °C (ACI 306, section under 300 mm)
- Print the page and fill in each reading on site
ACI 306 Minimum Concrete Temperature
| Least section dimension | Minimum temperature |
|---|---|
| Under 300 mm (12 in) | 13 °C (55 °F) |
| 300–900 mm (12–36 in) | 10 °C (50 °F) |
| 0.9–1.8 m (36–72 in) | 7 °C (45 °F) |
| Over 1.8 m (72 in) | 5 °C (40 °F) |