Cracks in a concrete slab ? - Views needed

[yourgardenworks.co.uk]

Alright all,

we have laid a concrete driveway around lunch time today and to my horror when i returned to check it over around 9 oclock ( tis only a hundred yds from my house) there were several rather large ugly cracks in the surface.

is this in any way normal for a wooden float finished driveway ?

anyways, the cracks have now been rubbed in and appear to have disapeared !

should i be worried lads ?

cHeers Dave

[dig dug dan]

i had the same thing on a slab, and i was told it was "plastic cracking".
It's caused when the subbase is too dry and it it absorbs water from the mix faster than the top which causes it to crack.

At least thats what the concrete gu told me when we complained

We now damp down our subbase before we lay the concrete

He said it was not stuctural, and not to worry, but we could brush neat cement dust into the cracks and it would be ok!

[seanandruby]

is that the finished job wood trowel finish? why no membrane d d d? no wonder it dried out like that.

[yourgardenworks.co.uk]

We placed visqueen under the slab and it also rained briefly, so it shouldnt have dried as quickly as that surely, i was able to walk on it roughly 8 hours after laying it though ?

[dig dug dan]

why no membrane d d d

The customer trimmed it off the spec last time, and argued that the old drive was not laid on one, so it wasn't required
To be honest, i have never found a concrete drive i have dug up with one to date.
A Garage slab is a different matter

[James.Q]

just had same prob a few weeks ago dpm used tamped finnish nice looking job. next morning cracks a plenty brushed cement into cracks all seems well after 2 weeks. plus sodding gpo managed to drive over the corner

[ex printer]

good job it wasnt a printed drive,usual suggestiions for cracks in p.i.c. on this forum are :
1. rip it out ,put down 'proper' sub-base.
2. Install block paving or bitmac for a 'proper' job.
3. Take legal action against the installer(if you can publicly name and shame them then all the better).

But luckily you only did a rough trowel finish , so rubbing a bit of opc into what you describe as large cracks should be perfectly acceptable!!!!!

Honestly the double standards on this site are unbelievable. I'm also very suprised that your sponser Simon from ronocrete hasnt stepped in allready to say that the only solution to this is one of his wonder-resin-toppings

[Dave_L]

Has someone got out of the wrong side of bed this morning??

Ex-printer - an ex-PIC contractor?

[James.Q]

dont think brushing opc on a pic drive would blend in to well :p

[yourgardenworks.co.uk]

The cracks are still visible after being rubbed in lightly by gloved hand/finger ooops, will they disapear given time or would it be advisable to "paint" the drive with a very wet thin mix of sand and cement ? the customer aint a happy bunny.

[seanandruby]

did you use a concrete batching firm, and did you put in crack joints? did you "close" it in with a steel trowel first ? could be it dried out to quick with the sunshine, maybe a wet hessian cloth over it once the slab could take it. years ago we would blind it with sand to protect it from the sun, cant remember now if that was a good thing or not.

[yourgardenworks.co.uk]

Wasnt "closed" first as far as i know, i was running around for bits while it was poured etc. but it wasnt very warm and the sun didnt make an appearance as far as i can remember, and no, we didnt place crack joints in the slab.

[seanandruby]

Concrete cracks as it changes in volume. According to the Portland Cement Association (PCA): "Concrete, like all other materials, will slightly change in volume when it dries out. In typical concrete this change amounts to about 500 millionths. Translated into dimensions-this is about 1/16 of an inch in 10 feet (.4 cm in 3 meters). The reason that contractors put joints in concrete pavements and floors is to allow the concrete to crack in a neat, straight line at the joint when the volume of the concrete changes due to shrinkage.

[seanandruby]

good job it wasnt a printed drive,usual suggestiions for cracks in p.i.c. on this forum are :
1. rip it out ,put down 'proper' sub-base.
2. Install block paving or bitmac for a 'proper' job.
3. Take legal action against the installer(if you can publicly name and shame them then all the better).

But luckily you only did a rough trowel finish , so rubbing a bit of opc into what you describe as large cracks should be perfectly acceptable!!!!!

Honestly the double standards on this site are unbelievable. I'm also very suprised that your sponser Simon from ronocrete hasnt stepped in allready to say that the only solution to this is one of his wonder-resin-toppings

What would you suggest ex printer?
The Brewers donate our time to try
and help both DIYers and tradesmen.
We cant go against mother nature, so
some jobs dont turn out as good as they
might. Have you ever made a spelling, or
grammer error in your work? Because we
dont agree on everything, it doesnt mean
that we are dealing double standards.

[James.Q]

What would you suggest ex printer?
The Brewers donate our time to try
and help both DIYers and tradesmen.
We cant go against mother nature, so
some jobs dont turn out as good as they
might. Have you ever made a spelling, or
grammer error in your work? Because we
dont agree on everything, it doesnt mean
that we are dealing double standards.

well said were trying to help not take the pxxs of a job gone a bit wrong :p