# Cement



## Steliz (13 Feb 2019)

Following my house renovation I have some cement left over which was used with aggregate to build a level floor prior to tiling. I'm now working on the basement (new workshop) and I have knocked down a wall which has left a 20cm recess in the floor, walls and ceiling all round. Can I use the same cement to fill the recess?


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## MikeG. (13 Feb 2019)

Steliz":3gg7hle9 said:


> Following my house renovation I have some cement left over which was used with aggregate to build a level floor prior to tiling. I'm now working on the basement (new workshop) and I have knocked down a wall which has left a 20cm recess in the floor, walls and ceiling all round. Can I use the same cement to fill the recess?



You're asking if unused cement powder has gone off in the bag?

If it is still loose and powdery, you can safely use it. If it has formed into lumps, you should sieve those out first. Obviously you need to mix the cement with aggregate to form a concrete or screed to do your infilling work to the floor.


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## Steliz (13 Feb 2019)

Hi Mike, thanks for the response.
The cement is still dry, that's OK, my question was more fundamental in that, is it the same cement that is used with aggregate for concrete that I could now use as a form of large scale polyfiller?
The reason I ask is that the builder used a different product when resurfacing the internal brick walls before plastering or tiling.


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## will1983 (13 Feb 2019)

The cement will be fine for that purpose but like Mike said you need to mix it with sand and maybe gravel to make a mortar or concrete mix.


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## MikeG. (13 Feb 2019)

Steliz":ff49ja40 said:


> Hi Mike, thanks for the response.
> The cement is still dry, that's OK, my question was more fundamental in that, is it the same cement that is used with aggregate for concrete that I could now use as a form of large scale polyfiller?
> The reason I ask is that the builder used a different product when resurfacing the internal brick walls before plastering or tiling.



All sorts of different things are used for plastering. I regularly visit Spain these days, and they use stuff I've never come across before, and do it in a very different way from the way we do. Cement mixed with sand and used on a wall is known as render. It is not a top-coat finish (ie you don't see it or paint it). It is a base for fine plasters to be applied to, in a process known over here as "render-and-set". If you are trying to plaster with a cement-based mixture, then you'll use a very different sand ("soft-washed" or "plasterer's" sand) compared with that you would use for leveling a floor (where you'd use "sharp sand"). The mixture is very different, too, being a sloppy mix like mortar, compared to a barely-damp mix used in the floor. Don't even think about using a cement based product for your ceiling, unless the soffit is concrete.

I don't want to put anyone off tackling simple DIY tasks like these, but you may benefit from watching someone else do these tasks, and asking a few questions. Getting the mix right is 90% of the job. If you can't stand next to a builder and learn how this is done, then at least watch some Youtube clips......and because of the differences in terminology, you'd be best watching some that are filmed in the same location as you (Hungary, I believe?).


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## Steliz (13 Feb 2019)

OK, thanks.
It sounds like the technique you describe from Spain is what they do here in Hungary. My builder just mixed the powder (looked like cement but came in a different bag than the cement I have left) with water in a very dry mix and coated the walls using a fibreglass mesh sheet to hold it in place and form the flat surface. Final fine plaster was skimmed on after.
The walls and ceiling already have a 20mm coating and the building is concrete floors with brick wall construction so the ceilings will be ok. I'm happy to do the work myself as I've already done what you suggest in terms of learning but my only concern was whether I could use up the leftover cement or would I have to buy something else.


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## MikeG. (13 Feb 2019)

Cement is almost never used "neat". The stuff your builder used for plastering, which looked like cement, almost certainly wasn't. There are many dark grey products which look like cement (thick-bed floor tile adhesive, self-leveling compound and many others), but they're not (just) cement. Buy some sharp sand or some ballast (mixed sand and small stones) and use the left-over cement to fix your floor, but buy specialist products to fill the gaps in your walls and ceiling.


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## Lons (13 Feb 2019)

Be aware that if it's old / opened cement it's very likely to go off quicker so make sure you get the tools / mixer cleaned before it sets. :wink:


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## Steliz (14 Feb 2019)

Thanks for the advice.
I've managed to find out what the builder used and the name translates as 'insulated glue' which is a cheap and weaker version of tile adhesive, apparently.


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## screwpainting (14 Feb 2019)

As a matter of interest, I assume you need to make good areas approximately 20cm wide, but you don't say what the depth is or the surface to be repaired. This makes a difference.


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## Steliz (21 Mar 2019)

screwpainting":znhrehth said:


> As a matter of interest, I assume you need to make good areas approximately 20cm wide, but you don't say what the depth is or the surface to be repaired. This makes a difference.



Sorry, just noticed your post. The depth was about 3cm. The house has concrete floors and brick walls. I followed the advice above and made a mix with some small grade gravel for the floor and put a render/ready mix product on the walls and ceiling. Job is done now and looks great. In a couple of days I'll have finished the rewire and then I can start moving my workshop tools and machinery in and get back to some wood butchery.


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## Bm101 (21 Mar 2019)

Pictures!


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## Steliz (22 Mar 2019)

Bm101":1wejks7m said:


> Pictures!



Here's some before, during and and after pics.



























I have some LED panels for the lights which I'll install once I have access to my workshop tools and can make the frames.
The socket on the end wall has been left until the rest of the rewire is finished as there is a 3 phase cooker supply buried in the wall somewhere!
The floor is concrete and has existing lino and I am considering whether to put another lino layer on top for comfort.


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## TomGW (7 May 2019)

Steliz":18t7rkwn said:


> OK, thanks.
> It sounds like the technique you describe from Spain is what they do here in Hungary. My builder just mixed the powder (looked like cement but came in a different bag than the cement I have left) with water in a very dry mix and coated the walls using a fibreglass mesh sheet to hold it in place and form the flat surface. Final fine plaster was skimmed on after.
> The walls and ceiling already have a 20mm coating and the building is concrete floors with brick wall construction so the ceilings will be ok. I'm happy to do the work myself as I've already done what you suggest in terms of learning but my only concern was whether I could use up the leftover cement or would I have to buy something else.



I think that the product your builder used is commonly referred to as 'bonding'. This is frequently used in repair and renovation work, where a sand & cement render would ordinarily be used on new walls. Bonding has a greater adhesion on 'low suction' walls, such as previously painted surfaces and is lighter in weight than sand/cement. However, it also has inherently less strength than sand/cement. The fibreglass mesh is to reinforce the bonding and reduce the likelihood of cracks through from the old/repaired/patched walls underneath.


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