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Repairing rain or water damaged concrete slabs

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Products and Tips for Repairing Rain and Hail Damaged Concrete

Practical advice to smooth out and rectify defects caused by rain and hail before concrete has completely cured

When laying new concrete that is exposed to the elements while it cures, it is important to protect the concrete from drying-out in sunny and windy conditions; and protect the surface from rain and water damage.

However, with typically unpredictable weather in the UK, it is possible to get caught out by sudden unexpected showers and other damaging weather conditions that haven’t been forecast.  If a newly laid slab is exposed to rain the surface will become pitted and expose aggregate by washing away the finer cement particles.

 rain damaged concrete

There is good news and bad news if this happens.  The good news is, and it is really really good news, the damage to the concrete is highly likely to be only surface deep and should not affect the structural performance of the slab.  The bad news is that you will probably need to do some resurfacing. If the slab is left without treating in any way then you are likely to be left with an uneven surface that dusts easily, has loose aggregate and as a consequence will wear faster when it is trafficked.

There are two different approaches depending upon the curing stage the concrete is at. 

If the damage is relatively minor, the concrete is still wet enough and the surface required is a brushed finish anyway it might be possible to brush in a bonding compound to consolidate the surface – obviously this will leave a brushed-finish to the slab so might not be ideal if you need a perfectly smooth surface.

If the slab has already cured beyond this point, then a thin surface repair will be required.  The right material to use will depend upon the thickness of the repair and whether or not the repair material needs to be feather-edged.  It is imperative that the damaged slab is prepared properly.  You can find detailed information on the specific preparation for each product on that product’s technical data sheet.  For any product it is imperative that any loose aggregate and dirt thoroughly cleaned off before the repair material is laid.

 For project specific detailed technical advice contact us on 01925852225 or email describe the situation you’ve got and we will help you find the best solution.

See also:

<link to thin section repairs>



Protecting newly laid concrete from the rain.

Laying vinyl/polythene sheeting and misting or damp hessian are traditional methods of stopping the slab from drying out too quickly, that can also protect the surface if there is a downpour of rain.  There are also purpose designed-concrete tent covers that suspend pvc sheets on a metal frame above the fresh concrete.

New Guard Coatings (North West), Unit 16, Rivington Court, Hardwick Grange, Warrington, WA1 4RT

Tel: +44(0)1925 852225 - Email:


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