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Posted: Wed Jul 13, 2011 2:15 pm
by Millsyy2k
Hi Everyone,
I'm glad I found this forum and hope someone can lend me some sage advice 
We recently had a patio laid on top of a concrete base. The contractor laid sand and cement first in order to make the ground level and then put the slabs down. When he had finished he poured a mixture of kiln dried sand and cement on to the slabs and used a broom to sweep it into the gaps between the slabs.
This was several months ago and we have had a lot of rain on and off since then. The patio is yet to fully dry out but it some of the places where it has we appear to have horrible concrete stains, images below.
The slabs are fairly rough and were marked by the mixture all over so we jet washed them, being careful to stay away from the gaps for fear of blasting out the mixture that had been swept between them. The slabs have come up looking much better than before but the stains close to the edges remain. I have tried a wire brush and it does remove the stains but also leaves a visibly scratched surface.
Should we call the contractor back? Did he do a good job and this is normal? Is there a way to solve this?
Thanks in advance for any help, this has been getting us quite down after saving up for so long to get the work completed and being left with a horrible sight!!
Posted: Wed Jul 13, 2011 4:46 pm
by lutonlagerlout
sorry millsy but that is a total fail
he could have just used kiln-dried on those saxons and left it at that ,but to mix it with cement shows pure ignorance of the hardscaping industry
try some hydrochloric acid but IME it will bleach the slabs too
LLL
Posted: Wed Jul 13, 2011 5:01 pm
by DNgroundworks
Wouldnt of been a bad job untill he mixed cement with the kiln dried sand.
Flags are on a full bed arent they?
Posted: Wed Jul 13, 2011 7:53 pm
by Millsyy2k
Hi Guys,
Firstly, thank you for your replies.
I'm showing my ignorance here, whats a full bed?
The base was concrete (already there) and they added almost 2 jumbo bags of sharp sand and 4 bags of cement on top of this. The slabs were then laid on top.
I noticed him using the cement and kiln dried sand and he said that it was fine to include the cement because of the colour of the slabs, if they were any lighter he wouldn't have used it.
Posted: Wed Jul 13, 2011 8:39 pm
by DNgroundworks
That doesnt seem alot of cement for the amount of sand.
A full bed is a bed of mortar that fully supports the paving, the opposite of spot bedding, which is very wrong.
There is no need for cement is KDS whether the flags are dark, light or whatever.
Posted: Wed Jul 13, 2011 9:22 pm
by GB_Groundworks
sounds like he screeded them like block paving but then added cement onto the screed then laid hte paving?
Posted: Wed Jul 13, 2011 10:09 pm
by lutonlagerlout
using KDS for jointing is something that can be done for effect,I have 1 client whose patio i did maybe 12 years ago,at the time there was a wet spell so we couldnt point ,anyway we added KDS to the joints as a stop gap
he liked it and every year, once a year he jetwashes the old stuff out and brushed in a couple of new bags
those saxons can be butt jointed but only if laid on a full bed
IME its asking for trouble butt jointing as seeds and bits of detritus will always get down the cracks and germinate
as dan said 4 bags of cement doesnt sound anywhere near enough for 1700kg of sand, thats a 1:17 mix
should be looking for 1:10 minimum,most lads on here use 1:5/6 mix,
was it knocked up in a mixer or just scattered on the sand?
have you a photo of the whole area?
acid is the only thing that will get that cement off but may bleach the slabs
cheers LLL
Posted: Thu Jul 14, 2011 9:33 am
by Millsyy2k
I want extend my thanks again for your advice on this. At the bottom of the post is a picture of the entire area. The sharp sand and cement was just thrown together, not in a mixer.
Acid doesn't sound like an option to me as the last thing we want is to risk making it worse. Elsewhere on this site in mentions a wire brush http://www.pavingexpert.com/stains.htm i have tried this and the stains do come off, but the slabs mark very easily in the process.
Honestly guys what do you think we should do here. I found the guy on mybuilder so have the option of leaving a stinking review but would rather come to some kind of amicable agreement about this. As a further note, when it rains we get a puddle in the middle of the patio!!!
I don't have any experience in this area so your advice on how to handle this would be greatly appreciated. The guy charged £400 and the materials cost us about the same (including the drain cover).
Thanks again.
Posted: Thu Jul 14, 2011 9:45 am
by Carberry
Get it fixed then leave a stinking review. He hasn't done anything right with that patio.
Posted: Thu Jul 14, 2011 10:15 am
by DNgroundworks
Agree with the above
1, The bedding is wrong
2, the jointing is wrong
3, it holds water, it aint supposed to be a water feature!
4, them cuts on the step overhang are naff
5, is it a bit high on dpc?
Give him a call, explain you problem and then direct him here
Posted: Thu Jul 14, 2011 5:37 pm
by joydivision
Also agree with the above.
If you wanted to try brick acid as also mentioned above to remove the staining, then you can dilute it right down and apply that. Then slowly bring it back to a stronger concentrate if need be and the flag does not dis-colour. Also try this on in an area which is least noticable, or better still on any spare flags you may have or off cuts.
But as others have said, the job isnt right to begin with.
JD
Posted: Thu Jul 14, 2011 5:44 pm
by joydivision
Oh, I would give him the chance to resolve the issues before leaving bad feedback.
But thats being hopeful!
JD
Posted: Thu Jul 14, 2011 6:17 pm
by lutonlagerlout
£400 labour doesn't buy a lot these days
to me it looks like he has some experience of paving but not enough
it looks too high to damp course
puddles are a big no no especially with that type of slab
maybe ask him to come and put the puddle right,but the pointing apart from acid and a hard brush you are stuck with
I know £800 is a lot of money,but it isnt enough to do a professional job ,including reducing levels, pointing etc etc
mybuilder isn't really a trade organization its just a place for people to try and drum up work
good luck
LLL
Posted: Thu Jul 14, 2011 6:38 pm
by Millsyy2k
With a bit of elbow grease and a wire brush I am able to get the concrete stains off. But it marks up the slabs as the brush scratches them. Is this scratching something that will fade?
Posted: Thu Jul 14, 2011 11:12 pm
by lutonlagerlout
not really
they are man made so you are abrading them
I would try acid first in an out of the way spot
LLL