The other cracking situation existing is at another control joint near the end of the driveway -- because the contractor stated the section was not cured enough a control joint was not sawed until 36 hours after the pour. The contractor said the crack would need to be opened and repaired. Does this cause that section to become weaker because of this crack and then a repair - or should this section be completely sawed through - removed and new poured?
One more question - the first section has some real defects in the finishing. You can see real bad uneven marks from the trowel machine, light footprints, etc. Is there anyway these marks can be taken out - like sanding the surface or?
Your comments will be of great help.
suggest: None - Your site is wonderful - full of great information.
Lenoir, NC
* Control joints can be added at any time to minimize future problems. I am not sure why you want to cut it past the rebar. If the joint spacing is correct, I would cut at the joint through the rebars. For the diamond-blade saw, cutting steel is as easy as cutting concrete. If the bars were placed in the center of the slab then all you need to do is cut through them and stop.* I tend to agree with the contractor that a hairline crack can be routed (opened) and repaired later. If it remains hairline I would actually leave it alone.
* Repairing a crack like that should not create a structural problem but will be very visible. It will probably come to a matter of taste.
* Surface defects can be removed by grinding. The same company that does the cutting will have the equipment. You need to realize that this area will look very different after grinding - you will see polished aggregates instead of the uniform grey finish of concrete. Even if done very lightly so that aggregates are not exposed the surface will still look different.
* One last note - After the concrete stabilizes (1-3 months) seal all the joints with flexible compound designed for concrete joints. This will keep water from getting through the joints and causing problems with the soil.
And the standard admonition - this answer is only as good as
the information you gave me...
The reason I asked about a new control joint below the rebar is, the concrete in the first section poured is very thick (greater than 6") on one side that joins a retaining wall and near the center - and the new section that joins this first section starts a major slope downward in the drive. This new driveway came about because the original contractor on my house did poor to no compaction under the drive and when I say no compaction - (I bought the house new but was already finished) that is true because it was like going through butter when they did the soil removable (24 feet down) the soil was wet and had to be dried, and then properly compacted. I also have a large retaining wall that joins at the corner of my house (13ft high, 52ft length) that was damaged and repaired, as well as damage to my exterior garage wall (retaining wall moved garage wall outward) - the current contractor anchored the retaining wall (did over kill on this which was great) and then tied the retaining wall also into the driveway with rebar. The house is cement block, with full brick veneer over it. This has been a $40,000 repair job.
I don't want any water to get under my driveway after what we've been through - so cracks make me feel very uncomfortable since they can be a source of water getting in. For as large as the driveway is, and to only have two cracks - I guess I should feel lucky. The crack at the control joint where the rebar is stayed pretty much in line along the control joint. The other crack down near the end of the drive - cracked as he was putting the control joint in and shoots across that section at an angle and does appear it is all the way through the cement. I say hairline - the first day it was hard to see - but now I can see it very plainly so it has opened some - however it is still a small width crack.
As for the finishing -- I thought only the first section had surface defects but looking last night with lights on the driveway I really could see a major part of the driveway is terrible - not so noticeable during the day - but at dusk with lights on you can see it very plainly - even foot prints. The trowel machine marks are deep in some places. I thought - we go through all of this repair and everything went great and then at the end I ask how could they be so careless. I'm happy with most of this project - but the driveway is a major part of the curb appeal to a home today - and I would like things to be as a they should be. I also would like to have the expense to the contractor to be as small as possible. That is why I asked about grinding or sanding the surface defects out. I wanted to do some type of edge design to take away this sea of concrete look - which I could afford to do but to stamp or spray over this entire drive would be more cost than I could afford ($12,000 - $18,000) and again, I ask - why should I have to to fix something such as a bad finishing job.
Also, if control joints can be sawed at anytime after - why am I seeing so much information about a window of time (6-12 hours) that control joints should be put in. The cracks did not exist until they started to saw the joint after 36 hours. The other joints were put in within this 6-12 hour window. Are you saying, the time limit does not matter?
Thanks for your response -- and yes you have one of the best and most informative web site I've seen - just wish I had found you before the project was completed.
If not yet and if the house is less than 10 years old, I suggest you get all your records and see a good lawyer who specializes in construction defects.
- the reason for the 12 hour window for joint sawing is to provide the joint before the concrete shrinks enough to crack, but after it hardens enough to support the saw and keep aggregates from being torn out. In your case this process is over, so a joint can be cut any time. This joint is not meant for initial drying shrinkage, but for future fluctuations caused by temperature and humidity changes.
Thank you again for the info and the update.