Cracks in limestone flags

[kamac]

I have laid my first patio, thanks mainly to the advice on this top notch website. I bought a kit of 25mm Natural Limestone which was delivered in a pretty poor state - almost 20% damage (but damaged slabs were replaced with no questions). However, I have since noticed that 3 of the slabs have cracks, which I didn't spot on laying. Is this going to cause long term problems, will limestone react over time and seal the damage or do I need to get to work on it? I also want to add a 500mm wide step above the patio just 50 mm below DPC is that a problem?

[Bob_A]

Sorry I can't give any advice as I'm a newbie myself but can you tell me what supplier you used.
Cheers

[kamac]

Bob - I bought the Bradstone patio kit on the internet through SimplyPaving, good price. When I reported the damage they offered a full refund or replacement of the broken slabs. I was in a hurry to finish the job so took the replacement option. All they asked for was an email with digital photos of the broken slabs. The problem I have is that these hairline cracks have shown up after laying the flags and there is no way to tell when the damage was caused. 25mm does seem frighteningly thin for natural stone flags, although you wouldn't think that when you have to carry and lay the bigger ones. :laugh:

[Bob_A]

The reason I ask is that I'm thinking of getting 22mm calibrated Stoneflair Indian Sandstone from simplypaving.
There was a debate on here just a few days ago about the pros and cons of internet buying.
http://ext.pavingexpert.com/cgi-bin....ony+mcc
I've come to the conclusion that it's a good idea if you're doing it yourself and have no time constraints but no good if you paying a pro to sit around waiting for replacements.
Sorry that doesn't help you with your original question although there's abit about "steps and ramps" and the dpc here
http://www.pavingexpert.com/dpc01.htm

[Pablo]

Are they actual cracks or do they look like fine fissures with glue in them. If they are like fissures then thats normal.

[kamac]

Pablo

I know what you mean, I do have some of the fissures you describe. But the ones I am talking about are ramrod straight and run the full length or width of the flag. They are different to the fissures in the way they break up the existing surface oxidisation on the stone. I am hoping that the natural action of water on limestone will eventually "glue" these together with calcite. I am very reluctant to lift them as everything is level. The stone is fairly rustic looking so my feeling is I can live with it, as long as it is not going to cause longer term damage.

[Tony McC]

The limestone will not self-heal, at least not in your lifetime.

You need to determine whether these are surface fissures or full depth cracks. If they are full depth cracks, you will have to appeal to Simply Paving's sense of public duty as they would be well within their rights to claim that the flags were damaged during installation.

[kamac]

Thanks Tony, I thought that might be the answer (though not exactly what I was hoping to hear). I will use your excellent site to find the best way of digging them out and replacing with new flags.