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[Sir Tigger KC]

I've got a big old stone retaining wall behind my house which is about 8 metres long and 5 metres high.

I'm always a bit worried that one day it will collapse and in places there is evidence that it has moved.  So gradually I've been pointing, repairing and rebuilding parts of it. 

Approximately in the middle at the base there is an old coal hole and much of the brickwork is frost damaged so I need to replace and rebuild the brickwork.  The problem is that being a retaining wall it is quite wet at the base.

Is there an additive that I can use in my cement that will allow it to set in wet conditions? 

Thanks in advance! 

[Marks DTM Calib]

Thats one hell of a wall!

Cement based products will set in wet conditions anyway, you might want to add a bit of plasticiser to improve its workability and potentialy an additive to improve the frost resistance (although at the base of such a structure, the frost wont penetrate far due to the temp stabilising nature of the soil mass behind it).

A very important thing to do is make sure there is drainage at the base of the wall as very often, the thing that results in the demise of such structures is water build up behind them. 

[Sir Tigger KC]

It is one hell of a wall and probably over 100 years old!!    It's about 1 metre thick at the base and narrows as it goes up. It is angled back at about 70 degrees.

I'm not pointing the bottom couple of courses so that the water can escape and I've hammered 40mm plastic pipes into it at various points to try and take some of the ground water out. I've seen water dripping from some of these pipes so some success there! 

Yes I usually use a plasticiser anyway, but was wondering if there was anything specifically about for use in wet conditions.  Thanks! 

[Marks DTM Calib]

Cement based stuff will actualy set under water (although the extra water content can bugger the mix up), if its a stupidly wet environment then you could use some accelerator to speed up the drying (mix smaller batches), if its only damp then no issue.

For your pointing, consider adding some lime, it takes longer to set but has a natural 'healing' ability so if there is any slight movement or cracking it much improves the frost protection (works well for us on the railway bridges etc)

[Sir Tigger KC]

Cheers Mark! 

[Phil]

Use Sulphate Resisting Portland Cement (SRPC) instead of OPC/ masonry cement in your mortar mix

SRPC is specifically designed for below DPC conditions i.e. high moisture content

[Varche]

I've got a big old stone retaining wall behind my house which is about 8 metres long and 5 metres high.

I'm always a bit worried that one day it will collapse and in places there is evidence that it has moved.  So gradually I've been pointing, repairing and rebuilding parts of it. 

Approximately in the middle at the base there is an old coal hole and much of the brickwork is frost damaged so I need to replace and rebuild the brickwork.  The problem is that being a retaining wall it is quite wet at the base.

Is there an additive that I can use in my cement that will allow it to set in wet conditions? 

Thanks in advance! 

Sir Tigger. I have added you to my list of artisans should I ever need an OOF working party. damp, concrete, retaining walls, pointing. All words used a lot in Spain. As to the coal hole? Have you had a look inside it? It might be the entrance to a whole new world, maybe a lucrative mine. Can you see any winding gear above this wall?

[Sir Tigger KC]

I've got a big old stone retaining wall behind my house which is about 8 metres long and 5 metres high.

I'm always a bit worried that one day it will collapse and in places there is evidence that it has moved.  So gradually I've been pointing, repairing and rebuilding parts of it. 

Approximately in the middle at the base there is an old coal hole and much of the brickwork is frost damaged so I need to replace and rebuild the brickwork.  The problem is that being a retaining wall it is quite wet at the base.

Is there an additive that I can use in my cement that will allow it to set in wet conditions? 

Thanks in advance! 

Sir Tigger. I have added you to my list of artisans should I ever need an OOF working party. damp, concrete, retaining walls, pointing. All words used a lot in Spain. As to the coal hole? Have you had a look inside it? It might be the entrance to a whole new world, maybe a lucrative mine. Can you see any winding gear above this wall?

A working holiday in Espana sounds fab, El Varche!! 

The house in question is in The Rhondda Valleys, South Wales.  So I may well have my own private coal seam behind this wall..... I've often wondered!!    The coal hole itself is more of a niche, about 5 foot wide, 5 foot deep and about 6 foot high with sadly no secret doors or tunnels..... or none that I've found as yet.... 

[Taxi_Driver]

Thats one hell of a wall!

Cement based products will set in wet conditions anyway, you might want to add a bit of plasticiser to improve its workability and potentialy an additive to improve the frost resistance (although at the base of such a structure, the frost wont penetrate far due to the temp stabilising nature of the soil mass behind it).

A very important thing to do is make sure there is drainage at the base of the wall as very often, the thing that results in the demise of such structures is water build up behind them. 

posh word for washing up liquid 

[Sir Tigger KC]

Thats one hell of a wall!

Cement based products will set in wet conditions anyway, you might want to add a bit of plasticiser to improve its workability and potentialy an additive to improve the frost resistance (although at the base of such a structure, the frost wont penetrate far due to the temp stabilising nature of the soil mass behind it).

A very important thing to do is make sure there is drainage at the base of the wall as very often, the thing that results in the demise of such structures is water build up behind them. 

posh word for washing up liquid 

Would you splash out on Fairy Liquid or is Tesco Value washing up liquid OK?