You can usually walk on it within a day or two, but it needs considerably longer before it takes vehicle weight — concrete keeps gaining strength for weeks after it's poured. We'll tell you exactly when it's safe for your specific pour, and it's worth respecting: driving on green concrete is one of the few ways to permanently ruin a slab that was laid perfectly well.
Some fine surface cracking is normal in any concrete and isn't a structural problem. What prevents the serious cracking is what goes in underneath — a properly compacted sub-base, the right thickness, reinforcement where it's needed, and movement joints in the right places. We design for it rather than hoping.
Yes, within limits. Concrete doesn't cure properly in freezing conditions, so hard frost will stop us. In cold-but-not-freezing weather we can use protection and adjust the mix. Sustained heavy rain during or just after a pour is the other problem. We'd rather delay a day than pour into bad conditions and hand you a slab that's compromised from the start.
