100 meter disaster! Help Help

[Parastou]

Hi
Last summer we used buff colour paving slabs for 100 square meter of the garden and bricks for the driveway. As the final work we covered the slabs and bricks with diluted cement to fill the gaps between them and protect them from movement and water. And washed it after one hour but it ended to a disaster! The colour changed! We tried to remove the grey cement with a brush and it didn’t work. This year after a winter and a lot of rain there is difference in the colour even in each single slab. So the area looks like an old pavement. Is there any way to colour it with the same material. Do you think that the cement colours that can be found in DIY shops can help us? I can send some digital photos.

Many thanks

 

[RigidRaider]

Would acid work?

 

[3GHOTHEAD]

Would acid work?

Good stuff that brick acid, it probably would help but do you recon the cement might have penetrated the slabs. Some of the cheaper ones fade like a good un. Personally I would bleach em to death and use a jet washer afterwards. P.S. dont mix the brick acid with the bleach as it creates chlorine gas and I dont like the taste of it. PPS brick acid good for cleaning toilets ,tiles , limescale etc, cant get enough of it.Oh and keep it away from metal finishes.

 

[Parastou]

Thanks, I have tried acid and bleach [ not mixed] but it didn’t work. The problem is difference in colours : grey, dark buff, light buff, and some lemon! Even in one single slab there are different colours. I am looking for a way to colour them with the same material as the slabs and seal them. Could you advise on this please?
Isn't it poor slabs material? Any chance to claim from the supplier? However my problem isn't money but the look of the garden.

Regards

 

[3GHOTHEAD]

Thanks, I have tried acid and bleach [ not mixed] but it didn’t work. The problem is difference in colours : grey, dark buff, light buff, and some lemon! Even in one single slab there are different colours. I am looking for a way to colour them with the same material as the slabs and seal them. Could you advise on this please?
Isn't it poor slabs material? Any chance to claim from the supplier? However my problem isn't money but the look of the garden.

Regards

I think I know the slabs you are talking about,buff with shades of grey,try wetting them down and see if the overall appearance improves. if it does when wet then use a coulour enhancer / sealer. If your not happy with them at all then ask the supplier. You say you used brick acid but the thing is it sounds like you have a layer of dried hard cement slurry film in places. My suggestion would be to use some brick acid on one of the worst slabs and scrub it in,leave it for 5 minutes and carry out again. You can see if there is any cement left on the slab as the acid will foam/turn white as it eats the cement. This should sort it, dont dilute the acid, get from B AND Q MAIN STORES 10LTRS ABOUT £7.00. some of the dye might come out of the surface of the slab. If this process improves it then carry out all over. best of luck. If this dosnt help ime at a loss, but a high power petrol jet wash would be my next step.P.S the method you used to grout them was wrong in that you should have used a very dry mix of sand cement and let it dry properly before attempting to clean.

 

[shenks]

Phew... seem to be doing a good bit of posting tonight (my first night registered here), anyhow... on to the problem in hand...

Diluted cement over all the flags is never a good idea - there is no substitute for professionally pointed paving (or at least pointed the correct way by a competant DIY-er)

As to whether the cement has caused this staining... difficult to say but it would be the prime suspect. Since you have already tried acid and also bleach there isn't really anything else I can suggest.

"Low quality" paving slabs can be prone to quite a few problems that reduce the asthetic appearance (it can happen with expensive slabs too, but maybe not quite as often):

1. Sunlight causing UV fade of the dyes used in the manufacture. some colours are worse than others in this regards - reds especially!

2. "Aggregate bloom" where the top surface wears and exposes the stone/gravel in the concrete mix. Can be caused by a number of factors including problems with the manufacturing process.

3. Post-manufacturing storage practices causing differential curing - exhibited as mis-match in colours between centre and edge of individual slabs.

 

[JohnD]

On the point of the cement eating acid... although useful for cleaning bricks (which are made of burnt clay) if you use it on a concrete paving slab, it is going to eat the slab as well as the stain.

 

[Slogger]

take them all up and turn them over it works for cushions