Mastic for cracks in concrete pad

[DrFfybes]

The previous owners of this place had a polytunnel, 17 x 6 metres, on a songle pour concrete pad with no expansion joints.

We're using part of it for a timber workshop on a single course of brichs, but there are a few narrow crack in it now we've cleared the stuff off and given it a jetwash. The cracks are pretty straight and about 2-3mm wide, the base has been down about 12-15 years and is 4 up to 8 inches thick in places.

I think the cracks may be where the re-mesh sheets meet, or even from the initial contracton when it set, but I intend to get the disc cutter and take them out to about 4mm and 30-40mm deep, then use some sealant to fill them.

In the good old days this would have been polysulphide mastic for expansion joints, but I cannot find anything like this at Toolstation/Screwfix/Wickes on their website, so am obviously looking for the wrong thing.

The seal will run all the way across the base, inside and outside the shed, so can someone tell me what I should be looking for or what would be suitable?

Thanks

Paul

[88V8]

I might use Arbomeric MP20 https://www.arbo.co.uk/products/modifie ... eric-mp20/

I say 'might' because I would ask Adshead Ratcliffe whether any of their other products is more suitable.

They are my go-to for any sealant job that matters. They will also supply any necessary primers. Try asking a builders' merchant for primer for any of the sealants they stock, and I guarantee they won't have it because none of their customers use it..... Stuff that comes out of a tube, the botcher's friend... but it doesn't have to be.

V8