Nasty surprise

[gordon]

The US product looks fine for filling and sealing a crack, but the repair method tends to push the sides of the crack apart - possibly elongating the crack.

Here in the humble old UK the Metalock people...

http://www.metalock.co.uk/Typical_On...n_Repairs.aspx

...do it differently. They use formers to drill ACROSS the crack at intervals and drive in a tapered dog-bone type of insert which pulls the sides of the crack together, and then they use pins like the US ones to seal along it. This is a much more satisfactory system from a mechanical point of view.

I can see you are in Australia, a fair distance from them, but I'd recommend them highly if they had a local agent, though these days it is probably an arm-and-a-leg job for a site visit. I was more than happy but then it was twenty years ago.