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Posted: Wed Mar 17, 2010 4:09 pm
by mlinklater
Advice/help needed. Over a year ago November 2008, we laid a new terrace of Stonemarket polished sandstone, large area, the cement used to lay stones was just standard cement, should have been white cement. Within 6 months most stones had cement marks but not all, some areas of the terrace are fine.
The company that laid the stones have been very good and plan top replace the stones shortly but with a different stone. We really like the polished sandstone and was wondering if these marks will ever work there way out of the stone.
It appears that some stones are not as bad but this might just be wishfull thinking.
Any thoughts most welcome!!!
Mark
Posted: Wed Mar 17, 2010 4:42 pm
by lutonlagerlout
when you say cement marks, what do you mean?
had the cement somehow come through the stone
or did they mark it when they laid it?
a picture would be very handy to analyse your problem
how to upload pictures
cheers LLL 
Posted: Thu Mar 18, 2010 1:20 pm
by mlinklater
Thank you very much for your reply.
The marks came through the stone, they were fine for a couple of months or so then they started to show, picture links below, hope you can access these okay.
http://picasaweb.google.co.uk/lh....ectlink
http://picasaweb.google.co.uk/lh....ectlink
Thank you.
mark
Posted: Thu Mar 18, 2010 6:45 pm
by lutonlagerlout
the whole thing looks very odd indeed
i would have said spot bedding caused it but i notice some areas are much worse than others
was any attempt made to seal these flags?
its a very plain looking layout for such expensive flags ,at first glance it looked like 450 by 450 biscuits,did you not consider a pattern or random layout?
regards LLL
Posted: Thu Mar 18, 2010 7:55 pm
by ken
ive seen a similar problem as yours before. The driveway was laid using Marshall's plain pressed concrete flags 600x600’s in natural (not by myself). My first thoughts when viewing the drive was, the flags were laid on blobs with massif cement content and the stains were caused by that.
The home owner had power washed the paving with a small electric power washer and had used some B&Q’s own brand “patio cleaner� attached to the detergent hose that some power washers have on them. And the finished result was the same as shown in mlinklater’s photos. The clients claimed on there home insurance for me to replace the driveway (ive no idea how they winged that one!). Also, the existing stained flags where laid on a full sand/cement bed and not blobs.
Posted: Fri Mar 19, 2010 2:10 pm
by Tony McC
That looks very definitely like cement discolouration with the flags laid on spots/dabs.
This problem has only been making itself known for 5-7 years or so, and therefore it not easy to be definitive about whether the staining weathers out or not. Most of the problems I've seen have occurred over the past 3-4 years and on those that have been around for that long, while weathering has ameliorated some of the marks, they've never completely disappeared.
The best results seem to come when algae is allowed to colonise the surface on a more or less permanent basis. Whether the algae is just discolouring the surface and helping to hide the marks or whether there is some sort of cement-munching activity taking place by the algae/lichens, I don't know. Could be an interesting PhD for some job-dodger at University?
Posted: Mon Apr 05, 2010 1:20 pm
by brucerogers56
Hey Linklater,
I read your post, and clicked onto the pics, and recognised the marks straight away. I've been laying sandstone slabs and tiles for a long time, and I've had this problem before too, long time ago.
The 'bloom' isn't salt bloom, ie, from too wet a mix, too lean a mix, etc. And I've never seen it occur from too strong a mix, ie, too much cement in the mix.
Without fail, each time I've seen it, it's from certain additives in the mix. The pattern that shows on your sandstone pavers, is probably from the way the bed was 'furrowed' before laying the stone, and/or 'spotting' the back of the stones before laying.
The actual discolouration is from additives in the gauge water, which 'bleeds' through the stone, and alters the colour and even texture in bad cases, on the surface of the stone.
The most common modifier I have seen do this to sandstone, is latex admixture. Over here in Australia, the usual situation is that the tradesman is doing a 'faster' job, and as insurance, he puts latex liquid into the gauge water/mix, as insurance that the job will hold up. However, it may be a different situation with your job. Remember also, that sandstone is one of the most porous stones, also some of the softer Indian stones, and as such will, typically over a period of weeks to months, depending on the type and amount of modifier added to the mix, gradually 'bleed' through to the surface of the stone. (Yes, you can see it getting worse over a period of weeks or months.)
I would suggest that if the marks come and go, with a natural wetting/drying out cycle, it's probably sand and cement bed that has been 'spotted' or irregularly furrowed, but if it's there all the time, it's an additive problem.
As I said, I got caught out with this problem a long time ago, and have seen it since on jobs around the place, and each time I enquired as to the mix design, the answer was latex additives.
BTW, if an installation is affected this way, sealing only further accetuates the problem.
Stone
Posted: Mon Apr 05, 2010 7:20 pm
by lutonlagerlout
g'day and welcome to the brew cabin bruce
fancy a cuppa?
LLL
Posted: Tue Apr 06, 2010 2:32 am
by brucerogers56
Hey LLL, how are ya? Thanks for the welcome to the site!
And what an awsome site it is. So good to access a site with a wealth of solid information. Just love it. It's the best technical site I've ever seen on any masonry type trades work, and it's great that it spells out answers to much that the novice/DIYer has questions about.
Wish there was a similar resource for cement rendering.
Anyway, thanks mate,
Bruce Rogers
Australia
Posted: Tue Apr 06, 2010 9:04 pm
by lutonlagerlout
wel bruce we have all sorts here
me brickie
dan and giles diggers and stuff
mickg,jay , and ken block paving maestros
sean all things steel and concrete
flowjoe drainage expert
our indomitable gaffer tony mc
and lots and lots of quality pavers
and some of the finest DIYers
TBH its nice to see a point of view from a different country
we have had lots of discussions on cement render and everyone seems to have a different way of doing it
sbr and waterproofer in the mix seem de rigeur
cheers LLL
Posted: Thu Apr 08, 2010 12:44 am
by Suggers
Welcome Bruce from me also mate - not the same since they banned smoking in here (we have to go outside in the freezing) - working with a couple of Aussies at the mo - Mick & Fred from the Mixtures - came over to do top of the pops in 1971, married english sheilas, and never went home....
Posted: Thu Apr 08, 2010 1:21 pm
by brucerogers56
Hey Suggers, thanks too for the welcome!
Well I know what you mean by 'no smoking in here.' Bummer.
So, working with a couple of blokes from Oz, huh? They must be the kind who don't mind the cold. I hate it! I had the priviledge of doing a house in stone veneer (I specialise in stone veneer), about 2hrs south of here(SW Sydney), about 18mths ago, in the Southern Highlands. It was so cold, the only fond memories I have are driving out of the place once a fortnight to get supplies. I got snowed on, and sleeted on, for two hours after doing too much pointing up of walls, but had to finish the job, so had to continue.
How do you guys handle the cold?
How do you get any work done? My coldest days here, I could only work for about 4 or 5hrs, cause the mud wouldn't set. One day, I had to pull down my previous day's work, cause the mud was just soft and slush.
Do you have probs with sand/cem laying course in the cold over there?
Regards,
Stone
Australia
Posted: Thu Apr 08, 2010 7:16 pm
by irishpaving
Top of the Morning Bruce.
Rules over here are temp needs to be 4deg and rising. You will always find loads of hessian and polythene. LLL is the top builder here and i'm sure he'll tell you the effects on winter. But he loves winter so who knows :;):
Posted: Thu Apr 08, 2010 8:29 pm
by lutonlagerlout
i prefer the spring and autumn
I dont mind the cold,i wore shorts for a whole year at work once for a 50 quid bet===> and he welshed
but i prefer temperate weather for working 15-20 degrees suits me fine
you have the old "slip slap slop" in oz dont ya bruce?
summat to do with sunburn?
i have heard that sunburn is terrible,a mate of mine went to spain once and caught a dose of it :laugh: :laugh:
all the best
LLL
Posted: Thu Apr 08, 2010 9:36 pm
by brucerogers56
Mornin to you too Irish. Yeah, rule's the same here, 4degC and rising, although I find in practice, it's better not to work too close to critical temperature. For me, 6degC is alarm bell time. Thing is, if it only gets up to 8degC in the middle of the day, it doesn't allow you much working time. Working in areas like the one I described in previous post, I worked with a thermometer beside me, and constantly checking it.
And always mindful of the fact that in the next two hours it could dip below 4deg.
One day the temp got up to 6degC, and the wind chill factor at one stage was -12deg. Not my style at all.
On the other hand, I've worked on stone floors in 45degC, which presents it's own set of probs, both for the material, and the lucky person who finds himself in that situation.
Yep, sunburn here is a real problem in summer. I've already had half a dozen skin cancers cut out on my back. But 20yrs ago, we didn't really know what it was doing to us, and baked in the sun all day. Some roofing tilers still do it.
Well, gotta go to work, finishing up a job I was already paid for 10 days ago. Bugger.
Stone