Anybody know anything about concrete?


New Member
I just has a garage build and am in the process of having a driveway dug out and poured. The slab in front of the garage is about 23'-40'.

Here are some pictures of what the contractor has done so far. I believe that he has just compacted the soil and laid out the forms. What do you think?


  • DSC00435 (Small).JPG
    DSC00435 (Small).JPG
    41.6 KB · Views: 111
  • DSC00451.JPG
    61 KB · Views: 106
  • DSC00452.JPG
    58.8 KB · Views: 112
I don't know that much about concrete, but I can tell you to make sure they put REAL expansion joints (vs. cosmetic ones) aligned with EVERY square corner or you will get diagonal cracks through the slabs.

What type of reinforcement are they going to use? Rebar or mesh?
Look at the way the water is puddling in the second pic. You would hope that the water runs away from the garage, it appears that there is a low spot in the middle of the driveway.
Vector said:
Is the grade sloping away from the garage?
Of course you don't want water running into the garage.

Yeah, it looks like you might need a trough in front of the door to take the water away. The wather that used to soak into your yard is now going to head straight for the garage.
Thanks for all the input guys. I share many of your concerns. I was standing on my back porch taking the picture. There is a small lake behind my house and the yard slopes away from the house to the lake.

The water was supposed to drain away from the house and garage towards the lake. Obviously this is not the case. I hired the contractor, through good references, to do the garage and the driveway. He has taken his sweet time on the whole deal.

The work that he has done so far has been of fine quality, but I just got around to checking the pitch of the roof and it is only 7/12 instead of the contracted 8/12. This has caused me to lose 1 foot in ceiling height in the attic. No small sum. Obviously, it is too late to fix this. What would you do about this.
If it is written in a contract you would have some recourse. Unfortunately, that recourse might be court. And, in such case you would have to put a number/ dollar amount on the loss, it would have to be a reasonable dollar amount loss.
Try to work it out with the contractor first; document everything; maybe even have a witness that you try to resolve it with the contractor prior to court action.
Good luck.
How much a square?

That driveway should take about 1 day with 2-3 people,5-6 hours of work.Depending if they knew what they were doing.....And thats including preping the area with the Bobcat and finsihing....
I hope he is compacting yellow sand and not on site material. They can change the slope of the drive when they pour the concrete. How thick is your slab ganna be. What psi is the concrete tested as. I dont know if it was the visqueen but was there snow in those pics? you cannot pour on ground that cold, the crete will not cure right.
Lost a foot of ceiling hieght

I think I would be very concerned about this. Not only has this saved the contractor qite a bit in materials, but labor. All of which you paid for. I would not be surprised to find a 1500 or more profit for the contracter by doing this. I wouldd break down the total job to price per square foot, to determine what the cost is. The contractor would have done a similar equation when Bidding for the job. SOmething to think about.

Concrete issues

The prep before the pour is very important. The thicker the compacted stone the better. In Illinois we call it CA-6 its basically 3/4 inch stone with fines that when compacted locks in place and makes for a great base. I would insist on at least 5" of compacted stone and when I say compacted I mean with compacting machine, not the guy in the bobcat running back and forth over it and spreading it out. Thats too important to overlook. I would check the local building code and see what the requirements are for the area and use that to your advantage when u bring up the other issues like the slope. Also the dryer the concrete as its coming out of the chute the stronger it will be, also insist on at least an 8 bag mix. That will be strong enough to prevent the unwanted cracks.
Find out what the depth of the sub-base will be below the concrete slab-on-grade. Also, what is the proposed thickness of the slab going to be?

This information will determine the reinforcement of the concrete. If it were my driveway, I'd have them correctly place welded wire mesh reinforcement in the pour AND put fiber mesh in the concrete. The mesh should be installed up off the sub-base about an inch or two so that the concrete flows around it when poured.

Also, I second the idea of CORRECT expansion joints. Concrete, by nature, will crack. It's not a question of if it will's when and where it will crack. We've been telling customers that for years, and they think that once concrete is cured, it won't crack. Completely wrong.

Check with the concrete supplier and find out what the mix design is and what the anticipated compressive strength will be after 7 days and 28 days cure time. If it's anything less than 3,000 psi, I'd tell them to take a walk.

Two is correct use the highest psi concrete you can afford. I had a new house built a while back and had to have three floors poured before the contractor got it right ( I was there for the prep work and the pour:)) I would make sure some where in the design that you use steel reinforceing rods, make sure you have real expansion joints and in the absense of reinforceing rods use the biggest gage of reinforceing mesh possible. After the pour, make sure the concrete cures slowly. If it is 32 degrees or lower make sure the mix has chemicals added that will make the concrete cure slowly. If you want to avoid cracks there are fiberglass additives that will strengthen the mix and will prevent cracks. Make sure the driveway is covered and that it cures slowly.


Oh yeah like rhunt was sayen if it is that cold out have dispatch add cloride to the mix, probably about 2%. Now with the cloride, It is ganna want to dry fast, so you should keep spraying the top with water at least 3 times a day to keep it wet. the slower you can keep the concrete from drying the stronger it is. Now if the highs for the week are ganna be in the low 30's I WOULD NOT POUR, I repeat DO NOT POUR. The concrete will freeze, that is very very bad.

As for reinforcing the concrete, just standard steel mesh will be fine, all that does is keep it together when it cracks. No need for re-rod, thats what we use for trench footings incase if the footing breaks, it will not walk or sink. Like said earlier go with 3,000 psi concrete. We poured a 6' slab and this will hold a dumptruck trailer and backhoe with ease.
Just a casual observer's definitely looks like there is a low spot in the middle where the forms come together. That will forever suck for you. Unless he's got that angled in such a way that it runs to the right or left, you'll have a pool of water there every time it rains.

My first house had a concrete driveway. I miss it a lot. Could jack stuff up on it without the jack sinking and it looked great, too.

I'd go after him over the 7/12 vs. 8/12 thing, too, if you had it in writing.