Setting and curing are two different clocks
Concrete "sets" fast: within one to four hours it stops being workable and hardens enough that a footprint or a dropped tool leaves a permanent mark. That's not the same thing as being strong. Setting is the concrete losing its plasticity; curing is the much slower chemical reaction, cement hydrating with water, that actually builds the compressive strength the slab is rated for. Boral's own Australian Concrete Guide is blunt about the difference: "the process of transformation is most rapid during the first 28 days," and that transformation "will not achieve its potential strength" if the concrete is allowed to dry out early, which is why every trade guide on curing comes back to keeping the surface moist, not just leaving it alone.
Cement, Concrete and Aggregates Australia (CCAA), the industry's own technical body, publishes the actual numbers behind that: concrete cured properly for just three days reaches over 60% of its eventual strength, seven days pushes that meaningfully higher again, and the gains beyond seven days are real but proportionally smaller each day after. A separate CCAA-derived data sheet on residential driveways and paths sets the minimum wet-curing period at three days for standard foot and light-vehicle pavements, extended to seven days for anything within a kilometre of the coast or carrying heavier traffic, exposure conditions that make early strength and durability matter more, not a fixed one-size-fits-all number.
The real timeline
Standard residential concrete (N20 grade) curing at a typical ambient temperature. Hotter or colder weather shifts every figure below later, not earlier.
| Milestone | What’s safe | Time after pouring |
|---|---|---|
| Initial set | Surface has hardened; don't mark, drag or work it further | 1–4 hours |
| Walk on it | Light foot traffic in soft-soled shoes, no dragging bins or furniture | 24–48 hours |
| Light vehicles | Cars and utes, parked or driven gently, no sharp turns or braking on the spot | 7 days (≈65–70% strength) |
| Heavy vehicles | Trucks, trailers, caravans, boats or delivery vehicles, plus full structural loads | 28 days (100% design strength) |
Vehicle-traffic strength percentages are of 28-day design strength, sourced from CCAA's own curing technical guide. In hot weather (32°C+) or cold (below 15°C), add 24–48 hours to the walking milestone and keep vehicles off longer, since both temperature extremes slow or disrupt the same hydration reaction.
Why 7 days is safe for the car, not the trailer
The table above is the practical version of that same curing curve. Walking on the slab is the earliest safe milestone, 24 to 48 hours, because a footprint is a light, brief, spread-out load with no shear or turning force behind it. A standard passenger car at the 7-day mark is the next threshold, and it's deliberately conservative rather than exact: seven days of proper curing gets a standard mix to roughly two-thirds of its final strength, enough for a car's weight and gentle rolling motion, but not enough yet for anything that turns sharply, brakes hard on the spot, or concentrates its weight on a smaller footprint, a loaded trailer jack point or a caravan's stabiliser legs being the obvious examples.
Full design strength, the number stamped on the mix as its MPa grade (N20 is the minimum standard for a residential driveway under CCAA's own guidance, higher grades exist for heavier applications), isn't reached until 28 days, the same 28-day mark every compressive-strength test in the industry is standardised against. That's the milestone that actually matters for a delivery truck, a loaded trailer, a boat, or a caravan sitting on its stands for a season, loads concentrated enough that the missing third of the slab's strength is the difference between fine and cracked. Driving a light car on day 7 isn't cutting a corner, the industry itself treats that as the safe threshold, but treating day 7 as good enough for anything heavier is the actual corner most people cut, usually without realising the slab was never rated for it yet.
Common questions
How long before you can walk on new concrete?
24 to 48 hours in mild conditions, using soft-soled shoes and avoiding dragged objects like bins or furniture. In hot weather above 32°C, or cold weather below about 15°C, allow the longer end of that range or a little more, since both extremes slow the same curing reaction that gives the surface its early hardness.
How long before you can drive on a new concrete driveway?
About 7 days for a standard car, driven and parked gently, no sharp turns or braking on the spot. At that point the concrete has reached roughly two-thirds of its 28-day design strength, per CCAA's own published curing data, enough for a light vehicle but not yet for anything heavier.
How long until new concrete reaches full strength?
28 days. That's the industry-standard age every concrete compressive-strength test is measured against, and it's the milestone that actually matters before parking a truck, loaded trailer, caravan or boat, loads concentrated or heavy enough that the strength still missing at day 7 is the difference between fine and cracked.
Does the same 'the calendar rule is really a threshold' pattern apply to other outdoor projects on this site?
Yes, laying turf works the same way. Our turf timing guide finds "spring or autumn" is shorthand for soil sitting above roughly 18°C, the same shape as concrete's "give it about a week" standing in for the 7-day, two-thirds-strength milestone on the way to its full 28-day cure.
Sources
Setting versus curing, and the 28-day strength-development window, quoted directly: Boral, Australian Concrete Guide 2023. Curing duration and its effect on strength (3-day/7-day/28-day gains): CCAA, Guide to Concrete Construction, Part V: Curing. Minimum curing periods for residential pavements (3 days standard, 7 near the coast or under heavier traffic) and the N20 minimum strength grade: Hunter Concrete/CCAA, Residential Concrete Driveways and Paths. Consumer walk/drive timeline and the approximate 7-day/65–70%-strength figure, corroborating the above: MixHub, How Long Does Concrete Take to Cure? and Booms Up Civil, A Homeowner's Guide to Concrete Driveways. All fetched July 2026.