New Driveway Cracking

[ÜberFly]

Gang,

 

Back in October I made an inquiry regarding getting a new concrete driveway sealed... Well, it's only been about 3 - 4 months and I've already noticed a crack (more then just a surface crack - 6' long and at least 1' deep)... I would expect that a newly poured (and sealed) driveway would last much longer then 3 months (I presume that they prepped it properly). I'm not sure of any warrantee at this stage as the contractor originally mentioned (verbally) that he would guarantee it for a year, but that is not written anywhere... So does anyone have exp. or suggestions on what to do or how to go about looking into this at this stage (will call the contractor tomorrow - Monday)?! Am I wrong to expect that a driveway would not crack within this amount of time?!

 

Thanks,

 

Peter

[Tungsten]

Most of the new houses i work in have cracks in them at only a month old.Very small ones but you can see them.

My guess is this is normal.

[Taco]

-35 one week +12 the next week pretty much guarantees some driveway cracking and heaving

[murray]

Peter, I dont buy the freezing a nd thawing thing. If that was the case it seems to me everything made out of concrete would be crumbling. I know some of the city sidewalks crack over time but there are more concrete sidewalks not cracked than there are cracked. Just because it warms up to + 12 doesn't mean the frozen ground that is covered with your cement warms up the same amount. My guess is that either the prep work was not sufficient, gravel base compacted enough, or maybe not enough rebar or wire mesh, or possibly the concrete might not be thick enough. Either way, you have a crack now and I dont know anything about repairs. I do know a guy in the mud jacking business. If that looks like an option, send me a note.

 

Murray

[ÜberFly]

Thanks for the replies thus far... It's about 10" - 12" off one of the corners of one of the slabs, so I figure it wasn't prepped properly... As I mentioned, we'll call the contractor tomorrow and go from there...

 

Cheers,

 

P

[lethfisher]

This might be of some help, I just finished a materials course at the university that talked a lot about concrete and we covered some durability issues. This is right from our lecture slides.

 

 

Early Stage Cracking

A, B, C —due to differential settlement of plastic concrete. Form before initial set (10 min. to 3 hours)

 

D, E, F —plastic shrinkage cracks. Form due to excessive evaporation (30 min. to 6 hours)

 

G, H —thermal contraction cracks. Cooling after excessive heat generation or high thermal gradients. Form after 1 day to 2 to 3 weeks

 

J, K —Crazing cracks. Inadequate curing and finishing combined with a surface rich in paste

 

Later Age Cracks

I —due to long term drying shrinkage. Form several several weeks or months after casting

 

L —due to corrosion of reinforcement. Accompanied by brownish extrusions (rust) from cracks. Form two years or more after casting

 

M, N —due to alkali-aggregate reaction. Form 5 or more years after casting, often accompanied by white silica-gel extrusion

 

I am guessing 'I' maybe? It is really dry in Calgary (especially in the winter) and can effect fresh concrete a lot if proper curing regiments aren't followed. Ideally the concrete should be kept moist while curing to keep from this type of thing from happening. If the concrete dries out while curing it can shrink, which causes these types of cracks. You can get different types of cement for different situations that can help combat different weather situations during curing, but that comes a higher cost. As for freeze thaw, it is possible to entrain tiny air pockets into the concrete to allow water to expand and contract in the concrete throughout the winter cycles preventing some cracking. Coming back to a common theme of this type of cement requires more money! It can happen that because of these extra costs, driveways and basic house foundations kind of get the 'bottom of the barrel' cement mixes which could lead to problems. Not always but it is possible! Hope that helps...

PS There is no such thing as a cement truck, it's a concrete truck

 

[Giovanne]

Funny/odd that you did not get/request the verbal "warranty" aformentioned in writing?!

 

You come across as such a stickler for detail?!?!

 

Let us know how your conversation goes with the contractor..

 

Cheers,

G

 

 

[Mudflap]

My 2 cents on your concrete troubles;

90% of all concrete cracking is due to workmanship. The diagram posted above is excellent but it does not tell you how those problems occur.

-Spalling and excessive shrinkage cracks occur from too high a slump when placed (easier for the finishers).

- Incorrect placement of expansion joint / sawcuts.

- Not kept wet during initial cure ( 2 to 7 days)

- Insufficient mesh placement or used mesh instead of rebar. Most of the time I see the mesh or bar laying on the gravel were it is useless.

- If you recall in Edmonton last year there where literally 100's of driveways and steps that literally crumbled from particular reputable home builders who were all using the same general concrete contractor. Inland concrete basically was in the news and said tough luck. Go after your general.

- During the salad days a small concrete contractor with a crew of 5 or 6 guys could form and pour around 3 driveways / sidewalks a day if they were good. At around $20K per house +- that is pretty good coin.

Worst of all I believe you still only have a one year warranty on new homes. Not much happens now a days at -20C.

 

My two cents

[ÜberFly]

Playing telephone tag with the contractor so at least he is returning phone calls... I'll chalk that up as a positive at this stage...

 

P

[misterbig]

My 2 cents on your concrete troubles;

90% of all concrete cracking is due to workmanship. The diagram posted above is excellent but it does not tell you how those problems occur.

-Spalling and excessive shrinkage cracks occur from too high a slump when placed (easier for the finishers).

- Incorrect placement of expansion joint / sawcuts.

- Not kept wet during initial cure ( 2 to 7 days)

- Insufficient mesh placement or used mesh instead of rebar. Most of the time I see the mesh or bar laying on the gravel were it is useless.

- If you recall in Edmonton last year there where literally 100's of driveways and steps that literally crumbled from particular reputable home builders who were all using the same general concrete contractor. Inland concrete basically was in the news and said tough luck. Go after your general.

- During the salad days a small concrete contractor with a crew of 5 or 6 guys could form and pour around 3 driveways / sidewalks a day if they were good. At around $20K per house +- that is pretty good coin.

Worst of all I believe you still only have a one year warranty on new homes. Not much happens now a days at -20C.

 

 

 

 

 

I couldn't agree more....the contractor that pored my driveway punched the rebar holes to close to the surface of the garage slab and 3 years later I ended up with large chunks from the edge of the slab popping off. I removed the chunks to put patches and that was when I noticed that they had the rebar only 1 inch below the surface. Home warranty did nothing, contractor told me that concrete is not a covered product unless it is structural(basement walls), builder told me they can not do anything for me. Neighbor of mine works in concrete industry told me that i would have to cut out 2 to 3 feet of concrete from my slab and re-pore. (cost could be $5K)

 

very sad.... They pored 6 drive ways on my block in one day(8 guy crew)