cement cracks??

[83trekker]

Its been a year now since I built my garage and the cement floor has a lot of hair line cracks going from one side to the other, front to back sides to side. At the moment you cant put your finger nail in between them, but there is a slight height difference say 1 mm if that. Am I going to be alright? Anybody have this happen to them? Im a worrier!!

 

[elsensei]

did you cut control joints?

 

[83trekker]

no the cement guy did not at all, i solid slab perfectly smooth.

 

[Lloydthumper]

Same here Mine is about 3 months old now and I have one hair line crack just starting. The height difference sounds like a settleing issue maybe the ground was not compacted enough. Mine has not changed in height yet I have a 30x40 with no control joints. I asked about them and he said it would not matter so I left it alone and they had the saw out if I wanted them to do it. I am waiting to see myself.

 

[StingRay]

Mine has some small hairline cracks but it also has control joints. By the looks of things around here it would need a control joint every 8 feet to really make a difference. My garage is 28 x 44 and as I recall there is one up the middle at 14 feet and two cross ways down the 44 foot length so that would make it just a little over 14 feet between them. I don't believe in cold climates you are likely to have a crack free slab that big without a number of true expansion joints.

 

[elsensei]

you gotta have control joints to crack, or else cracks go everywhere. i diamond-wheel cut my joints 18 hours after the pour and my 24 x 60 slab is cut into 28 squares. overkill? maybe...but no cracks!

 

[logical]

Are the cracks fairly straight and parellel or perpendicular to the walls? If so your contractor may have used "zip strips" (instead of saw cuts or expansion joints) which are plastic inserts embedded that force cracks in specific controlled lines.

 

[Vicegrip]

I anve found that using rebar along with or rather than mesh the slab will be far less likely to shift out of level when it cracks. I used plenty of bar in the shop slab and let it crack where it wanted to. Some fine line cracks but no lips.

 

[brownbagg]

cement always cracks, but if you would added some aggregate and sand to the mix and had a concrete slab, then it would of been stronger