Can you pour concrete in cold weather?
Yes, with protection. ACI’s cold-weather guide counts it as cold weather when the air has fallen to, or is expected to fall below, 40 °F during the protection period, and NRMCA says fresh concrete must be protected from freezing until it reaches about 500 psi, roughly two days after placing. Keep it curing for at least 7 days, ideally above 50 °F.
How to work it out
- 38 °F: below 70 °F → 7 days (Quikrete; NRMCA gives 3–7 days typically)
- Mix: Standard mix — Posts and light loads after 24 hours (Quikrete Concrete Mix)
Cold doesn’t ruin concrete by itself; freezing does. Water in fresh concrete that freezes before the concrete has any strength expands and damages it for good. Everything about cold-weather work is about keeping heat in for the first couple of days.
Adjust for your project
- Setting
- Sets and hardens within about 2–8 hours of mixing (NRMCA) — slower in the cold
- First loads
- Posts and light loads after 24 hours (Quikrete Concrete Mix)
- Strength gain
- ≈ 2,500 psi at 7 days, 4,000 psi at 28 days (Quikrete Concrete Mix lab figures)
- Freezing
- Protect from freezing for at least 48 hours (Quikrete); NRMCA: until it reaches 500 psi, about two days after placing
- For this temperature
- Cold weather by ACI’s definition (air at or below 40 °F during the protection period). Protect the concrete from freezing (insulated blankets, heated enclosures) until it reaches about 500 psi, and keep it above 50 °F to keep curing. Consider waiting for a warmer spell or asking the ready-mix plant for a cold-weather mix.
- These are the earliest points the sources give, under the conditions they assume. Heavier loads, vehicles and structural use need the strength your plans or supplier specify — ask them.
- A slab that freezes before it has gained strength can be permanently damaged. When in doubt, cover it.
Guidance by temperature (standard mix)
| Average air temperature for the next week | Moist-cure for | For this temperature |
|---|---|---|
| 30 °F | 7 days | Cold weather by ACI’s definition (air at or below 40 °F during the protection period). Protect the concrete from freezing (insulated blankets, heated enclosures) until it reaches about 500 psi, and keep it above 50 °F to keep curing. Consider waiting for a warmer spell or asking the ready-mix plant for a cold-weather mix. |
| 38 °F | 7 days | Cold weather by ACI’s definition (air at or below 40 °F during the protection period). Protect the concrete from freezing (insulated blankets, heated enclosures) until it reaches about 500 psi, and keep it above 50 °F to keep curing. Consider waiting for a warmer spell or asking the ready-mix plant for a cold-weather mix. |
| 45 °F | 7 days | Below 50 °F: setting and strength gain slow down — NRMCA notes a 20 °F drop roughly doubles setting time. Keep the concrete above 50 °F while it cures if you can, and don’t use curing compounds if it will drop below 50 °F within 24 hours (Quikrete). |
| 55 °F | 7 days | Mild weather. Quikrete calls for 7 days of curing between 50 °F and 70 °F. |
| 65 °F | 7 days | Mild weather. Quikrete calls for 7 days of curing between 50 °F and 70 °F. |
ACI and NRMCA cold-weather rules of thumb
- Definition: ACI 306R treats it as cold weather when the air temperature has fallen to, or is expected to fall below, 40 °F (4 °C) during the protection period — the first days when frost could harm the concrete. (Older guidance, still quoted in NRMCA’s CIP 27, used a three-day average.)
- Freezing: concrete freezes when its own temperature falls below about 25 °F; keep it from freezing until it reaches 500 psi, about two days after placing.
- Slower setting: a 20 °F drop in concrete temperature roughly doubles setting time, so finishing takes longer.
- Placement temperature: for sections under 12 in thick, NRMCA lists 55 °F as the minimum concrete temperature as placed.
What protection looks like
Don’t pour on frozen ground. Order concrete for cold weather — plants can heat the water and adjust the mix — and have insulated blankets ready before the truck arrives. Cover the slab once it can be covered without marking it, and leave the blankets on for at least the first two days, longer if nights stay below freezing. Quikrete’s data sheets say to protect its mixes from freezing for 48 hours, using plastic sheeting and insulation blankets if temperatures will fall below 32 °F.
Avoid curing compounds if temperatures below 50 °F are expected in the next 24 hours (Quikrete). And avoid de-icing salts on new concrete through its first winter (NRMCA). For when the slab can take traffic, see how long before you can walk on concrete and how long before you can drive on concrete; for setting posts in winter, how much concrete for a 4×4 post.
Different size? Use the full Concrete Cure Time Calculator.
What you’ll need
- Poly vapor barrier sheetingBudget price
Plastic sheeting under an indoor slab, and over a fresh slab to hold moisture in while it cures.
See options on Amazon (opens in a new tab) - Acrylic concrete cure and sealMid-range price
Rolled or sprayed onto fresh concrete, it holds moisture in while the slab cures and leaves a light sealed finish.
See options on Amazon (opens in a new tab)
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Frequently asked questions
Can you pour concrete at 45 degrees?
Yes, with care. Setting is slower below 50 °F; cure for at least 7 days and cover the slab at night if frost is possible.
How long does concrete need to cure at 50 to 70 degrees?
7 days, per Quikrete’s data sheet.
Other common sizes
- How long before you can walk on concrete — 4 hours for fast-setting mix; about a day for standard concrete
- How long before you can drive on concrete — Cars after about 7 days; heavy trucks after 28 days or when your supplier confirms
Sources
- Quikrete Concrete Mix (No. 1101) data sheet (opens in a new tab) — Yields: 40 lb ≈ 0.30, 50 lb ≈ 0.375, 60 lb ≈ 0.45, 80 lb ≈ 0.60, 90 lb ≈ 0.675 cu ft; unit weight ≈ 140 lb/cu ft; for pours 2 in thick or more; 6–9 pints of water per 80 lb bag; control joints every 6–8 ft; cure 5 days at 70 °F or above, 7 days at 50–70 °F; protect from freezing for 48 hours.
- Quikrete Fast-Setting Concrete Mix (No. 1004) data sheet (opens in a new tab) — 50 lb ≈ 0.375 cu ft, 60 lb ≈ 0.45 cu ft, 25 kg ≈ 11.6 L, 30 kg ≈ 14 L; sets in 20–40 minutes; post holes 3× the post width and ⅓ of the post length deep; wait 4 hours before loading a post.
- Quikrete 5000 Concrete Mix (No. 1007) data sheet (opens in a new tab) — 60 lb ≈ 0.45, 80 lb ≈ 0.60 cu ft; ≈ 140 lb/cu ft; 1,500 psi at 1 day, 2,500 at 3, 3,500 at 7 and 5,000 at 28 days; 2 in minimum thickness.
- NRMCA Concrete in Practice 11 — Curing In-Place Concrete (opens in a new tab) — Cure for typically 3 to 7 days; keep placed concrete above 50 °F (10 °C); concrete in a dry environment can lose as much as 50% of its potential strength.
- American Concrete Institute — ACI 306R-16 Guide to Cold Weather Concreting (preview) (opens in a new tab) — Cold weather: when air temperature has fallen to, or is expected to fall below, 40 °F (4 °C) during the protection period.
- NRMCA Concrete in Practice 2 — Scaling Concrete Surfaces (opens in a new tab) — Order air-entrained concrete (about 6% air) for exterior slabs exposed to freezing and de-icers; avoid de-icing chemicals in the first winter.
- City of Redmond, WA — Concrete crew FAQ (opens in a new tab) — A minimum of 7 days before passenger cars on new concrete; heavy loads not until 28 days.
- NRMCA Concrete in Practice 27 — Cold Weather Concreting (opens in a new tab) — Cold weather definition; protect from freezing until 500 psi, about two days; a 20 °F drop roughly doubles setting time.
- NRMCA Concrete in Practice 12 — Hot Weather Concreting (opens in a new tab) — Continue curing for at least 3 days; avoid adding water to concrete more than 1½ hours old.
- NRMCA Concrete in Practice 31 — Ordering Ready Mixed Concrete (opens in a new tab) — Truck mixers carry 8 to 12 cubic yards (about 6 to 9 m³); order 4–10% more than the plan estimate; a loaded truck weighs about 80,000 lb; fresh concrete can cause severe chemical burns.
- Penn State CE 584 — Curing (compiled from Kosmatka et al., PCA Design and Control of Concrete Mixtures) (opens in a new tab) — Cure at least 7 days (above 40 °F) or until 70% of specified strength; 3 days for high-early-strength concrete above 50 °F; air-dried concrete gains only about 50% of the strength of moist-cured.
- American Concrete Institute — FAQ: why is compressive strength tested at 28 days? (opens in a new tab) — Specified compressive strength is based on 28-day test results; 3- and 7-day results are not commonly used for acceptance.