The timeline everyone needs, then the details that keep your slab from cracking:
The curing timeline
| Milestone | Time |
|---|---|
| Initial set (no footprints) | 24 – 48 hours |
| Walk on it | 24 – 48 hours |
| Drive a car on it | 7 days |
| Heavy trucks / equipment | 28 days |
| Full design strength | 28 days |
| Sealing (if desired) | ~28 days |
Concrete reaches roughly 70% of its strength in the first 7 days, then climbs slowly to 100% at 28 — and technically keeps hardening for years. “Dry” and “cured” aren’t the same thing: curing is a chemical reaction (hydration) that needs moisture, which is why good crews keep new slabs damp, not dry.
When can you walk on new concrete?
Light foot traffic after 24 hours in warm weather, 48 in cool — but keep pets, bikes, and pointed loads (ladders, chair legs) off for 3 days. Footprints pressed into day-one concrete are permanent.
When can you drive on new concrete?
7 days for passenger vehicles, 28 for anything heavy — and park away from the edges for the first month, since edges are the weakest zone. Driving early is the most common cause of driveway cracking (see what a redo costs in our driveway calculator — early cracks are expensive lessons).
Weather rules that matter
Rain: fresh concrete needs 4–8 hours before rain won’t damage the surface; cover with plastic if showers threaten. Heat: above 90°F, concrete sets too fast — pour early morning and mist-cure. Cold: below 40°F, hydration stalls; below freezing, new concrete can be ruined — use blankets or wait for a warm window. Curing happens fastest between 50–85°F.
The mistakes that crack slabs
Skipping control joints (cut them within 24 hours, every 8–10 ft), letting the surface dry out in the first week (mist it or use curing compound), loading it early, and pouring on uncompacted base. Notice none of those are about the concrete itself — curing failures are almost always process failures.