I'm not sure if this should be posted here or in the garage and workshop forum so I appologize if it's in the wrong place. Last Thursday I had a concrete drive poured to my shop and I'm wondering how soon I can use it. I really need to get my Explorer and utility trailer out of the shop and all I want to do is drive across it not park on it. Would you chance it?

 

What type of mix is it?

Did a contractor do it? If so, he should have given instructions as to when you can drive on it.

Usually, concrete attains its yield strength @ 28 days. Of course, there are many variants in mixes. Modifiers added for high-early strength, pouring when below freezing, etc, all can affect the curing time.

Personally, I would wait at least 7 days unless instructed otherwise.

 

I agree, I'd wait a day or two more. You might be able to push it a little if you have some wide planks to put down, but even though it looks dry and you can walk on it, the concrete is still "green" inside. Try not to chance it.

 

I had a 6" thick sidewalk poured accross my gravel drive a while back. A few days later I had a loaded dumptruck drive accross it. It was fine. I think you are also.

 

I work for a concrete business, and I know when we pour walls we strip the forms the next day. And when we pour floors we are walkin on the floors within a couple hours, by the end of the day, it is solid. There are trucks driving on the floors within the next day or two....so I would think you would be all set to drive in within a day or two. Hope this helps.

 

Hmmm... I know when we are doing large commercial jobs we are not supposed to strip structural concrete forms for days, sometimes longer.. I have been told cure time can be up to months for the structural stuff as well... Read an article that said Hoover Dam won' t finish curing for a few more decades, but thats a whole heck of a lot more concrete than any of us will ever use. You should be set to drive on it by now, to answer your question in a really round-about way.

 

Concrete generates heat as it cures. The thicker it is, the longer it takes to cure. Hoover Dam has pipes embedded in the concrete. Chilled brine was pumped through them to remove heat while the concrete cured. Supposedly it would have taken a hundred years (maybe more, I forget) to cure without the cooling.

Structural forms are typically left on longer than other pours. I think the reason is to allow the strength of the concrete to build more before starting to hack at it pulling the forms off. I suppose the reason is to lessen the likelihood of causing internal cracking which would weaken the structure.

Concrete does not "dry". It "cures". There is a chemical reaction going on which consumes the water as the cement hydrates and locks the aggregates together. Leaving the forms on longer will also likely help it stay damp.

When my folks had their driveway poured, they were told to mist it down every couple of hours during the day for a week (it was poured in July). This was to prevent the concrete from drying in the sun. They were told they could drive and park on it after a week, but keep heavy vehicles off of it for a month. It worked for them. The driveway still looks great almost 19 years later.

Cheers,
Eric

 

After 7 days and normal curing conditions you can drive on it with an average weight vehicle.

Water the concrete everyday to speed up the process.

Temp = Not hot... not cold...just right

 

There can be a lot of differences between the stuctural concrete pour and a side walk or driveway. Most of the pours I do are between 8 and 20 foot square and usually 4 foot thick. I always tell the drivers I want between a 3.5 and 4 slump. Even if I have to get up and help push it down the shoot. We have get a test sample off every truck. If it's right I have to really move to get the thing finished as soon as it's poured. On that type of pour, we strip the next day. Being as thick as it is I can see what it's doing when the forms come off. Usually, the top foot is pretty well set up, but still warm and it can be steaming below that. It's set up, but soft - like crusty, three day old bread. I can walk on it, no problem, but it doesn't take much to break off a corner. It always looks hard on top.The samples are tested a week later and they are usually at about 50% after 7 days. The curing slows down after that. It's still not cured totally after 28 days, but it should be "cured enough" by then to be within specs.

If we do a job in an area where the concrete company isn't expirienced with this type of pour, (or for other cost saving reasons), they try to give a real sloppy pour. They think they are doing a favor, because the guys that do sidewalks and the average homeowner likes more time and needs a lot of cream. That type of pour takes hours before you can broom. The testing usually comes out weak and we have to wait the full 28 before we can go back to work on it.

You might be able to drive on it now, but after 7 days you won't have to worry. Water's good - I'd turn the sprinkler on now.

 

Wait atleast 8 days, and you should be safe. Concrete cures in 28 days as stated before - but , sometimes it takes up to years to get full cure (if at all.) I have seen people drive on concrete the day after a pour-- not recommended at all.

 

In all honesty, concrete allmost never stops curing. The chemical process goes on for years.

I allways recomend to my cutomers to keep off fresh concrete for 7 days. It reaches 50-80% of it's design strength in the first 5-7 days. I ALLWAYS cover my slabs with plastic, just to keep the fresh concrete hydrated. Slower cures, generally means a stronger product.

 

Worked in a concrete lab at BASF long ago.

We tested after 24 hours, 3, 7, and 28 days, and plotted the strength. It cures the fastest starting from when it is mixed, and gradually curing slower and slower over time.

There is an exact amount of water that can react with the cement in concrete mix. Any amount of water in excess of that leaves the concrete through channels, and when the water is gone from those channels, empty spaces are left behind. That is why slump is important. Concrete should have the minimum amount of water needed to work it. Any more causes it to be weaker.

 

For 17 years he's been waiting to find out if his concrete was hard enough to drive across.

OP, I agree with 2019er. I think after 17 years it's hard enough to drive on.

 

lol - why did this show up as recent?

 

Were you doing a google or other external search?

Or were you doing a search here by a specific word that also appears in this thread?

Or did it turn up as a "related thread" when you were looking at or replying to another thread?