Fresh concrete

[Paul G]

I had my driveway extended to make it wider. It was done last Friday so it has been 7 days since the pour. I am told I can drive on it now, but waiting longer is better. They say concrete fully cures in 29 days. Should I wait or start using it? Also keeping it wet is better? True or not? There are dark patches in it, same color as the wet concrete, will they fade out over time? 

[ralley72]

I had my driveway extended to make it wider. It was done last Friday so it has been 7 days since the pour. I am told I can drive on it now, but waiting longer is better. They say concrete fully cures in 29 days. Should I wait or start using it? Also keeping it wet is better? True or not? There are dark patches in it, same color as the wet concrete, will they fade out over time? 

Should be OK to drive on and park a car or truck on. Hopefully they use reinforcement and air in the extension.
Concrete paving/drives curing time will varies depending on multiply condition at time of placement, mix design, sub-grade condition/materials, air temps. applied curing/sealer compounds after finishing.
Using water is a method of curing concrete, if your contractor used a good quality  curing compound after finishing, wetting the concrete is not needed unless in extreme high temperatures  to slow the evaporation of the moisture that's in the concrete, when the water evaporates to quickly from the concrete it causes spider cracks.
Unsure what the dark spots are. Maybe the crew chewed Red Man and that where they spit. Just kidding on the chew part.

Mike

[John_Kunkel]

One week is the usual period contractors prefer before driving on new concrete. Lighter vehicles can use it even sooner.

[RallyeMike]

Standard driveway mixes which are typically around 5-1/2 to 6 sacks of cement per yard can hold the weight of regular passenger vehicles without a problem after three days. At 7 days you are fine. The reference to the 29 day (28 day) strength is just the standard measure of concrete strength for what will be close to its full strength, even though it will continue to gain a moderate amount of strength even after that.

Curing it with water or other means after 7 days is unnecessary. It's only the first few days that are important.

Color variations depend on what caused it. If it is because of uneven curing compound placement, it will fade after several months depending on weather.

[John_Kunkel]

even though it will continue to gain a moderate amount of strength even after that.

The concrete in the Hoover Dam (completed in 1936) is still curing. 

[Patronus]

^ They also had to install cooling pipes in the construction to counter the heat given off from the mix hardening.

[Paul G]

I started using it yesterday, 14 days after the pour. The dark areas have completely faded out. The slab is a uniform color and looks great. Thanks for all the replies.

[68CoronetRT]

The Hoover dam's concrete is'nt even cured yet!

[RallyeMike]

That has been established already, but did y'all know that the concrete at the Hoover Dam is still curing?

[67440chrg]

I was told years ago that it cures for 100 years and then starts to slowly break down. I have cored and hammer drilled 50 year old concrete that was hard as heck.