Poor Driveway Job??


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Old 01-01-06, 09:06 PM
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Poor Driveway Job??

I live on the western slope of Colorado. Midsummers are in the 90s, November and winters can drop as low as 0. And this year they have.

In July 2005 I had my driveway replaced. The concrete contractor said 4 inch thickness is usual for homes. I asked for "6-bag" and he said okay. I asked about reinforcement with rebar and he said today's concretes have fiber in them and don't need reinforcement.

I asked him about expansion material between the driveway and the house foundation. He said it would just be another place water could get into.

Guarantees? He laughed. Like the other contractors I interviewed.

The job cost about $6000 for a double driveway and an adjacent RV park slab.

He removed the old double driveway from the garage to the sidewalk, let the dirt dry for 3 days, packed it, then poured it. During the pour the workers complained that the concrete was pretty dry. After the pour, stress relief grooves were made to make about 10 by 10 foot squares. He placed an expansion strip between his concrete and the city's sidewalk.

When the stuff dried, two of the 10x10 squares were much whiter than the rest of the work. I watched the pour and the same batch was used across the stress reliefs. I wonder to this day why those squares are whiter.

month later, every stress relieve had a crack. In December, one of the slabs cracked in 3 places. These are not surface cracks, but run 10-12 feet.

Isn't 5 months a bit soon for cracks to develop?

How the heck am I supposed to know what comes out of the concrete truck?

The contractor told me he can't be responsible if the ground shifts and that's what he told me is causing the cracking.

The neighbor had his done the previous year and no cracks.

Other concrete driveways in the neighborhood, and even on my property, haven't cracked in 20 years.

Do I have any recourse?
 

Last edited by Pipsisiwah; 01-01-06 at 09:10 PM. Reason: More information
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Old 01-01-06, 09:44 PM
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Poor Driveway Job??

The cracks at the "stress relief grooves" were to be expected.

The cracks in the 10 x 10 panel were not due to shrinkage since the shrinkage cracks were where they were planned to be. The most likely cause of the cracks in the 10x10 panels is a lack of sungrade suport. (How to you get a 10 to 12 foot crack in a 10x10 panel?)

Fiber mesh is not a good substitute for steel reinforcement when there is a poor subbase. If you had steel, you may not have had this crack, but who knows. Fiber mesh was developed to minimize shrinkage cracks and it works well for that purpose.

Since he removed the concrete he would be responsible for compacting the base as it was or to a sufficient amount to support the slab. It sounds like they may have dug to deep while removing the old concrete and did not compact the soil that was replaced. It happens if the crew gets a little sloppy. "Shifting of earth" is a general condition not to be confused with localized lack of support.

He should remove the bad slab and replace it. Since he was doing work in a city, he must have a license. I would push him, complain to the ready mix supplier saying you had bad concrete and contact the city or whoever licenses contractors. If he also does sidewalks for the city, this may help you get some leverage.

You may not have gotten bad concrete, but you don't know it and it will get a supplier involved that wants to do further work within the city.

In our area, 4000 psi with 5% air entrainment is the minimum that will be supplied for a driveway. I use 5000 psi with 5% air, fiber mesh AND 6x6 wire mesh.
 
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Old 01-02-06, 06:52 AM
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The whiter squares were most likely from water in the broom that they textured the slab with. Sometimes, a finisher will find that the concrete is a little too dry on top and the broom is either rolling up little balls of cement, or not leaving good broom marks. He then wets the broom, shakes it out, and commences brooming again. The next several passes of the broom leave moisture on the slab which makes the concrete bleach out whiter. This could be repeated as he moves down the driveway.
Another reason is shade vs. sun. If one area of the drive gets very little sun and another gets a lot of it, the shady section will remain darker for a longer period. This is compounded if the driveway was sealed before it cured and the colors were not matched yet.
The last reason I can think of would be if one section was covered with plastic sheeting or something that made it cure at a different rate than the uncovered section.
As to the cracks, the ones in the joints probably happened within a few days of the pour. That's what the joints are for, and it sounds like they worked as planned. There should have been expansion material placed between the pour and the garage, but I doubt this is causing the other cracks. Do they by chance originate off a corner? For instance, if the concrete was poured against a brick, and the concrete is against more than one side of that brick, then there is a corner there. Or if there is an "L" in the driveway, there is obviously a corner as well. Cracks like to start at corners pointing into a slab (re-entrant corners) Joints need to be placed at corners to control them. In addition, for a joint to be really effective, it should be cut a minmum of 1/4 of the way through the slab. For a 4" slab, the joints should be at least 1" deep. Sometimes finishers use jointing tools that have worn down to considerably less. Then cracks can jump out of the joint and run diagonally through the slab.
Last question: From the time the driveway was poured until now, have any large trucks (Garbage truck, moving van, dump truck, school bus, etc.) been on the driveway? If so, they may have caused the cracks just from being too heavy. There are a lot of factors to consider.
One thing I would do is to contact the contractor and ask for a copy of the batch ticket from the concrete plant. If he doesn't have it, the batch plant will. The ticket should tell you the mix design of the concrete, if it contained fiber, how wet it was delivered (slump), and how much water was added on site at the contractor's request. Sometimes the drivers don't write in the added water, but they are supposed to. Sorry for the long winded response, but I hope some of it helps.

Pecos
 
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Old 01-02-06, 12:20 PM
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"The job cost about $6000 for a double driveway and an adjacent RV park slab."

How long did you keep off the driveway with the RV?

He should have used 6x6 reinforcement mesh plus the fibermesh. Fibermesh is nice, all I have been using, but not all by itself either.
 
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Old 01-02-06, 06:48 PM
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>>The cracks in the 10 x 10 panel were not due to shrinkage since the shrinkage cracks were where they were planned to be. The most likely cause of the cracks in the 10x10 panels is a lack of sungrade suport. (How to you get a 10 to 12 foot crack in a 10x10 panel?)>Fiber mesh is not a good substitute for steel reinforcement when there is a poor subbase. If you had steel, you may not have had this crack, but who knows. Fiber mesh was developed to minimize shrinkage cracks and it works well for that purpose.>Since he removed the concrete he would be responsible for compacting the base as it was or to a sufficient amount to support the slab. It sounds like they may have dug to deep while removing the old concrete and did not compact the soil that was replaced. It happens if the crew gets a little sloppy. "Shifting of earth" is a general condition not to be confused with localized lack of support.>He should remove the bad slab and replace it. Since he was doing work in a city, he must have a license. I would push him, complain to the ready mix supplier saying you had bad concrete and contact the city or whoever licenses contractors. If he also does sidewalks for the city, this may help you get some leverage.

You may not have gotten bad concrete, but you don't know it and it will get a supplier involved that wants to do further work within the city.
 
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Old 01-02-06, 07:01 PM
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>>The whiter squares were most likely from water in the broom that they textured the slab with.>>

Looks like that's exactly what he did because the white parts fill the 10x10 panels and do not extend beyond the joints (grooves?) Looks pretty bad to me.


>>As to the cracks, do they by chance originate off a corner?>In addition, for a joint to be really effective, it should be cut a minmum of 1/4 of the way through the slab. For a 4" slab, the joints should be at least 1" deep.>From the time the driveway was poured until now, have any large trucks (Garbage truck, moving van, dump truck, school bus, etc.) been on the driveway?>Sorry for the long winded response, but I hope some of it helps.
 
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Old 01-02-06, 07:03 PM
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>>How long did you keep off the driveway with the RV?

No got no RV.
 
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Old 01-02-06, 08:03 PM
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Poor Driveway Job??

Sounds like the control joints are working well enough to break everything up into the 10x10 panels for shrinkage control. You color problems seem to be explained and cannot be immediately corrected, but aging will improve the uniformity.

The batch ticket will only show what the mix design was and what the desired slump was. Any slump test is unlikely. Probably will give no real information except a mix design number, admixtures and timing. It may provide some information on water content, but water could have been added later.

A "Y" shaped crack with a center in the middle of one panel and crossing a control joint and probably dieing in the adjacent panel sounds like a lack of base compaction. I errored when I referred to subbase when I really meant the base (road mix is apparently the local terminology). Concrete will only span so far over poor soil until there is a crack. The use of a "thumper" may be a local practice because of the soil type (clay) and the need for deep compaction. In many areas with granular soils a vibration plate compactor is used.

Since the crack apparently died in the middle of a slab there probably was not much displacement (My assumption). Just how wide are the cracks and is there any relative displacement from one side to the other?

How expansive is the bentonite clay and was the bentonite relatively wet or dry at the time of pouring?

The lack of wire reinforcement is very big point irregardless of the mix design or concrete quality (within reason). Without steel, concrete will crack.

Keep us informed of your findings.

Dick
 
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Old 01-03-06, 07:18 AM
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Cracks don't typically just die in the middle of a slab. They usually keep going until they hit something like the other edge of the slab. They are probably there, but so hairline as not to be seen. You would probably only see them when the slab is drying after a rain. The causes for the cracks could be as Dick stated. Either poor compaction/settling or possible frost heave in a wetter area under the slab.
As to the batch ticket, around here the drivers are supposed to write in any water they added on site. If the ready mix plant gets a call about bad concrete, they first look at the ticket to determine if a lot of water was added, thus putting the blame squarely on the contractor. They don't like to eat the cost of the load any more than anyone else does. However, I've noticed a lot of the drivers don't write in the added water. It's just a crap shoot as to how well your load was documented.

Pecos
 
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Old 01-03-06, 11:58 PM
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first off all quality concrete contractors should at least give a one year guarentee for material and workmanship if not keep shopping for one who does . your contractor must also have a city contractor license and show proof of a liability bond .now the good stuff yes you should have expansion joints when old concrete meets new , you should of had a well compacted subbase which was made to grade , a vapor barrier should of been placed down and if i was pulling a rv on it i would of had it formed for six inches using wiremesh and # 6 deformed rebar because thats quite a load ! control joints at least every 10 feet one forth the thickness of the slab and a eith inch slope for every foot for proper drainage with a 4000 psi in 28 days 6 bag air entrained mix . now the control joints did thier job you said the guys complained of the concrete being to dry perhaps they had the driver add more water which would change the batch which was ordered lessening the concrete value causing a color difference (two differnt mixes rarley look or set the same) because they were getting tired of raking a low slump and wanted thier job easier in the heat ? was the grade even proper ? ive seen some 2 inches in some spots 3 or 4 inches in others by inexperienced contractors ! alot of variables here! in southern ohio we charge $ 6 a sq.ft. what did you pay for ?
 
 

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