Posted: Thu May 23, 2013 7:32 am
I'm a builder and on a extension i was working on about a year and half ago a contractor came out to lay an indian stone patio. It was quite a large job in excess of 200sqm. The paving has subsequently started to lift in areas especially along a step and it appears as if the sand has buckled. I know that he used recycled grit sand using a full bed with a full bed at 4:1 mix. There's a minimum of 100mm of well consilidated hardcore with ground below the hardcore being sandstone it can't be due to ground movement. The sand and cement mortar mix just crumbles in your hands. I'm in contact with supplier of the sand with a view to having some chemical tests carried. I was wondering if anyone had come across anything similar before. The paving along the step has raised by approximately 50mm. I'm pretty sure that it's not water collecting under the paving and freezing and pushing the paving up as the sandstone is extremely porous and water drains right through it. We are going to reinstate the paving but need are trying to find out what has caused the problem before starting. Hope someone can help. Thanks Dan
