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  Thermo March 9, 2015 at 7:41pm

  dpm is an absolute no no as it will stain and leech through the slabs and it wont do any good anyway. we pva the rear of them.

  if the pointing is coming away then its either because the pointing has dried out too quickly when it was done or there is some movement in the slab where it hasn't bonded properly when laid. if the frost gets in it tends to kill it and crumble it out. have you got any pictures?
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  David Cox March 10, 2015 at 12:36am

  Some indian stones (fossil mint Especially) are very pourous, and if they are perpetually damp - IE north faceing etc or over damp ground then they will wick the moisture up and that could mean the mortar didnt bond to the paving when it was pointed.... Then again 4 years on my rear garden patio is 100% fine and is in the shade and damp.
  
  Could be down to the individual who did it? 5 Years ago I employed a lad who, despite watching like a hawk, had an uncanny ability to do pointing that crumbled - Even if sharing the mortar - I eventually put it down to him filling the join "fluffily" IE very loose and not pushed down firm/.
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  Colin Hunt March 10, 2015 at 8:42am

  Cracking can be caused by the mortar being too strong as well as too weak - or the wrong type of sand.  'Pit' or 'building sand' is not really suitable.  We use 'soft washed sand' at 4/1 with enough water to bind, but not stain the slabs, firmly trowel in and finish with 'ironed' or pointed finish to taste. I should add that sand varies with area.
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  Rory March 10, 2015 at 8:47am

  The only time i have seen what you've described has been when the mix has been to strong for the stone or the mortar not being 'firmed' in properly 
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  LSD.co.uk (Paving Supplier) March 10, 2015 at 1:20pm

  Hi Chase,

  We supply Indian stone paving nationwide and have mixed opinions about people jointing hand cut edges.   Some landscapers prefer their tried and tested methods of sand and cement with PVA on the rear of the slabs, others have dabbled with specialist jointing compounds and gone back to their own methods and then finally others have tried the specialist jointing compounds and fallen in love with them.  One of the main benefits is that they state the mortar will not crack, not to mention it doesnt stain the slabs and is very fast.  The two that we sell are Jointex and Romex.  After looking online these tend to be the favourites and have been our product of choice since Geofix was the main brand 5 or so years ago.  We do sample pieces if you want to look at the colours available and also discount for bulk.  If you do want to chat anymore please feel free to give me a call on 01142310911 or have a look on our website at the videos of Romex Easy.

  Best of luck

  LSD
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  ChaseLandscaping March 10, 2015 at 1:46pm

  We use a yellow sand with a 3 -1 mix.
  The pointing is firmly pressed in so im pretty sure that's not the issue.
  The two places that its happened are particularly damp gardens so I'm sure its the fact that the stone isn't bonding well and damp is getting in causing frost damage.
  
  Does pva help it bond better?
  And if so how diluted should it be and do you wait for it to dry before laying?
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  Simon Smith March 10, 2015 at 6:54pm

  What indian stone is it, Sandstone, limestone? Kandla Grey sandstone for example is worlds apart from fossil mint.

  It sounds more like the pointing mix was too dry or it was done when it was very warm. The small cracks where it appears the mortar wasn't bonding to the stone sounds like shrinkage cracks.

  Was it done traditionally by hand with damp to semi-dry mortar?

  What was the reason your stone mason mate wouldn't touch indian stone? Sounds like the usual I know something you don't know attitude which helps people feel superior but has little basis in reality
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  ChaseLandscaping March 10, 2015 at 7:44pm

  Pretty much 99% of our clients choose raj green.
  We point using a wet mix and pointing gun and press and smooth.
  The stonemason didn't say why, just said its a terrible stone for bonding to mortar.
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    Colin Hunt > ChaseLandscaping March 10, 2015 at 8:17pm

    That's interesting - 'wet mix' pointing at 3/1, that could be the problem, especially if the sand is 'building sand',
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      ChaseLandscaping > Colin Hunt March 10, 2015 at 8:29pm

      That's the way we've always done it and what I was taught at uni and never had any problems.
      Would you do it differently?
      Any reason this would be a problem?