By the ConConnect team · Updated August 2026 · Based on CCAA guidance, AS 3600 requirements and Australian manufacturer specifications
Trick question — concrete doesn't dry, it cures: a chemical reaction between cement and water that keeps building strength for weeks. The timeline that matters: walk on it after 24–48 hours, drive a car on it after 7 days, and it hits full design strength at 28 days. Here's every milestone in between, and how to protect the pour while it gets there.
Strength figures are the industry-standard curve for concrete cured properly at mild temperatures — heat speeds the early milestones up, cold stretches them out.
| Time | Milestone | What it means |
|---|---|---|
| 1–2 hours | Initial set | The mix starts stiffening — about 2 hours at 20°C, faster in heat, slower in cold. Screeding is done; edging and jointing happen in this window. |
| 4–6 hours | Final set | Hard to the touch and can no longer be reshaped. Rain from here on does little harm. |
| 24–48 hours | Foot traffic | You can walk on it (keep pets, bikes and mowers off). Edge formwork can usually come off from 24 hours. |
| 3 days | ~40% strength | AS 3600's minimum curing period for standard residential exposure — but keep curing; every extra day to day 7 is cheap strength. |
| 7 days | ~70% strength | Cars can drive on it, framing and brickwork typically start, and active curing can stop. |
| 14 days | ~90% strength | Can be painted with water-based paints. |
| 28 days | Design strength | The strength on the docket (e.g. 25 MPa) is measured here. Heavy vehicles are OK, and standard sealers can go on. |
Strength percentages are approximate (7-day figures range 65–75% across sources). Concrete keeps gaining strength beyond 28 days while moisture is present.
Because hydration needs water, the job after the pour is stopping the slab drying out. CCAA's testing puts a number on it: concrete left to dry out immediately reaches only around 40% of the strength of the same concrete kept moist — proper curing roughly doubles the final product. Once the paste dries, rewetting restarts the reaction but the lost strength never fully comes back.
The Australian rule of thumb — printed on practically every bag and product sheet — is keep the surface moist for 7 days, starting the same day you finish it. (AS 3600's legal minimum is 3 days for standard residential exposure, 7 for coastal and severe environments; the first three days do most of the work.) A gentle hose spray twice a day, wet hessian, plastic sheeting weighed down at the edges, or a sprayed curing compound all do the job — just avoid wet–dry cycles, and if you're using a curing compound, mention any plans to seal, paint or tile later, since compounds can affect how coatings bond.
Skimp on it and the symptoms show up for years: a dusty surface, poor wear resistance, crazing and cracks. Water is also why the mix itself matters — get the water-cement ratio right and don't add extra on the day to make it easier to work.
Australian standards want concrete delivered between 5°C and 35°C, with precautions once the day is under 10°C or over 30°C. What that looks like in practice:
Everything happens faster — set times shrink, the surface can crack as it dries, and concrete that cures hot ends up with higher early strength but a weaker final product. Pour early morning, damp down the subgrade, use windbreaks, and start water curing immediately.
Hydration slows right down — longer set times, delayed finishing, slower strength gain, so every milestone stretches. Below 5°C, fresh concrete must be protected: if it freezes before it sets, the strength loss is drastic and permanent.
Defer the pour if rain is due within about 4–8 hours of placing. The first 2–4 hours are the danger window — rain washes the cement paste off the surface. After final set it does little harm, and on hardened concrete it actually helps the cure.
Pouring a driveway? The wait times before parking on it are in the driveway cost guide, and the concrete calculator will size the pour itself.
Concrete doesn't dry — it cures, hardening through a chemical reaction with water. You can walk on it after 24–48 hours, drive a car on it after 7 days (about 70% strength), and it reaches its full design strength at 28 days. It keeps gaining strength for months after that if moisture is present — concrete can even cure underwater.
Best not to. The standard guidance in Australia is to stay off new concrete for 24–48 hours — at 12 hours the surface has set but is still weak enough to scuff and mark, especially in cool weather when strength gain is slower. If you must cross it, wait at least 24 hours and keep it to light foot traffic.
Usually, yes. The damage window is the first 2–4 hours, when rain can wash cement paste off the surface and leave it weak and dusty. By 4–6 hours the concrete has reached final set and rain does little harm — once hardened, extra water actually helps curing. If heavy rain arrives earlier, cover the slab with plastic and don't work the water into the surface.
A standard 100 mm residential slab follows the normal timeline: walkable in 24–48 hours, about 70% strength at 7 days, design strength at 28 days. Thickness changes how long the surface holds moisture, but the strength milestones are driven by the cement's hydration, not the slab depth — a thicker slab doesn't need proportionally longer before you can use it.
Common Australian practice is to start framing about 7 days after the pour, when the slab is at roughly 70% of design strength — and manufacturers give the same 7-day figure for brickwork on new footings. Some volume builders start sooner and conservative builders wait 14 days; on an engineered slab, the engineer's call wins.
It's the delivery rule, not a curing rule: ready-mix concrete should be discharged within about 90 minutes of batching (per AS 1379 requirements around elapsed delivery time), because the mix starts setting in the truck. It's why the site must be ready when the truck arrives — and why late pours get expensive.
Wait 28 days before applying standard acrylic or penetrating sealers — sealing earlier traps moisture and causes cloudy blushing, bubbling or peeling. The exceptions are purpose-made new-concrete sealers that can go on from 24 hours, and curing compounds applied at finishing (which can affect how later coatings bond, so tell your concreter if you plan to seal, paint or tile).
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