Cracks in Mortared Joints

[110-1093880618]

Hello Everyone,

I replaced an old poorly laid patio last August using riven slabs on a 10:1 bed. For the joints I used a 3:1 mortar mix. I noticed around June this year that at one end of the patio, where it butts up against the house brickwork, that the mortar has cracked along the edge (i've a photo I can send in). This has pissed me off enormously! Any ideas as to why this may have happened? Is it most likely down to settlement? Should I have used a Class 2 Sand, Lime & Cement mortar?

[danensis]

For any joint where movement is possible a lime mortar is much better than a cement one. For outdoor work you need to use a hydraulic or semi-hydraulic lime, as a fat lime will stay soft when damp.

[84-1093879891]

I can'y say why your pointing has cracked without seeing it for myself, but it's relatively easy to replace. It may be dues to thermal expansion/contraction of the vertical masonry, in which case, whatever you use to fill that joint, cracking will occur, so perhaps a dry sand or polymeric sand joint would be a better option.

[110-1093880618]

Tony,

Thanks for your reply and comments. I've a couple of digital pics I can email you which the forum might be able to draw some conclusions from?

[84-1093879891]

OK - info AT pavingexpert DOT com