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Gardening & Landscaping

White circles on my dark grey sandstone paving.

Anonymous user 28/02/2024 - 3.27 PM

I have a very large area of paving. All the slabs in dry weather show circles where the cement is underneath. They have also been sealed. My landscape gardener accepts the appearance is not acceptable but neither he nor I want to have to lift every slab and replace them. Can the sealant be removed and the slabs and cement allowed to dry out? Would that help?

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5 Answers

Patios & Drives Turfcare

Rating: 5 out of 5
Ross On Wye
Sorry The reason for the slabs showing spots is incorrect laying . They appear to of been laid on spots when they should of been laid on a full bed of mortar. The backs of the slabs should of had a pre-laying wash applied prior to laying. We use a PVA/cement mix but some use SBR/cement or a readymade wash. Unfortunately the only option is to lift and replace then lay correctly.
Answered20 February 2017
5

Italo Ficetola

Rating: 5 out of 5
West End, London
Hi you could try and chemical wash the tiles . Using a scrubbing Machine and Acid should sort out the issue . Please test a small area first preferably a hidden corner.
Answered19 February 2017
2

Walnut Contractors

Rating: 5 out of 5
Bangor, Gwynedd
these mortar spots are the result of moisture being soaked into the mortar 'dabs' below the paving and salts & minerals being drawn back up showing as 'spots' on the surface. unfortunately this cannot be eliminated completely with chemicals and cleaning. algae and litchen feed off these salt deposits as well and in time the surface spots will go green! the correct way of laying paving is on a 'bed' of mortar for future reference.
Answered19 February 2017
2

Anonymous user

A natural stone paving will naturally draw the salts from the dot and dab, these have been installed incorrectly, all natural paving should be laid on a full mortar bed consisting of soft sand, sharp sand and cement. The only way to rectify is to remove and replace using the correct method
Answered20 February 2017
2

SOS HOMECARE Home Improvements & Maintenance

Rating: 5 out of 5
Wellington
Incorrect laying,spot laying is a no no!! Any professional would lay a full bed and put a sbr on back of slabs So I’m sorry to say but this could have to be done again
Answered3 August 2020
1