# Concrete Curing and Maturity Calculator

Turn curing temperature into maturity and equivalent age, and check the code minimum.

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

## Quick result

With the default inputs (Mean curing temperature 20 ℃, Days cured 7 d, Cement type Ordinary Portland, Watertight concrete No): **Equivalent age at 20°C 7.0 d**

## Inputs

| Parameter | Type | Default | Unit | Note |
|---|---|---|---|---|
| Mean curing temperature | number | 20 | ℃ |  |
| Days cured | number | 7 | d |  |
| Cement type | select | Ordinary Portland | — |  |
| Watertight concrete | select | No | — |  |

## Formula

- **Maturity**: M = Σ (T + 10) × Δt (T in °C, Δt in hours)
- **Equivalent age**: te = t × (T + 10) ÷ 30
- **Temperature factor**: k = (T + 10) ÷ 30
- **Minimum curing**: 7 days OPC, 14 days slag, 14 days watertight

## Worked example

Seven days at 20°C gives 5040 °C·h of maturity, an equivalent age of 7.0 days and about 65% strength — just meeting the 7-day minimum for OPC. At a mean of 10°C the equivalent age falls to 4.7 days and strength to about 53%, so curing must be extended.

## Questions

### Why does winter curing take longer?

Hydration is temperature-driven and roughly halves for every 10°C drop — hence the T+10 term in the maturity function. Seven days at 10°C is only equivalent to 4.7 days at 20°C, a whole strength step lower. In winter, extend curing, insulate or heat, or use an accelerator; summer durations do not transfer.

### Is 7 days of curing enough?

That is the code minimum: 7 days for OPC, 14 days with retarders, watertight requirements or slag cement, longer for mass concrete. At 7 days strength is around 65% — enough to strike side forms but still a third short of the 28-day design value. Cure important members for 14 days.

### When can formwork be struck?

Side forms once the concrete will not spall — usually 1-2 days. Soffits depend on span: slabs up to 2 m need 50% of design strength, over 2 m need 75%; beams and arches up to 8 m need 75%, over 8 m need 100%; cantilevers need 100%. Those percentages refer to site-cured specimen results, not the estimate here.

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Generated by BuildCalc. All calculations run in your browser; no data is uploaded. Formulas follow national standards and common trade practice; local codes govern.