How do I repair the Benching in an Inspection Chamber?
Michael D
When I rodded my drains recently I found that the benching needs to
be patched in a couple of places in one of the inspection chambers.
The inspection chambers appear to be original, installed around 1914.
The places that need repair are just above the main flow so get wet at
times. I’m got some questions:
- Do I just use a normal mortar mix, or is it more likely it be
some kind of render?
- Anything I can do to help it dry more quickly?
- Anything I should do to make sure the new mortar sticks to the
old bricks succesfully?
Any other tips?
Michael
js.b1
> - Do I just use a normal mortar mix, or is it more likely it be
> some kind of render?
Benching is usually 3:2:1.
> - Anything I can do to help it dry more quickly?
Blue Circle Rapid cement may be ok - Extra Rapid will not be (and is
too fast anyway).
> - Anything I should do to make sure the new mortar sticks to the
> old bricks succesfully?
SBR considering this is a wet application.
I think B&Q do a 1L bottle relatively cheaply, check online and check
the solids contents.
harry
High pressure water jet the repair area toget rid of algea and shit.
Prevents the cement sticking :-)
Rick Hughes
"Michael D" <micha...@hotmail.com> wrote in message
news:2f214ae7-a540-47d5...@d17g2000yqb.googlegroups.com...
When I rodded my drains recently I found that the benching needs to
be patched in a couple of places in one of the inspection chambers.
The inspection chambers appear to be original, installed around 1914.
The places that need repair are just above the main flow so get wet at
times. I’m got some questions:
- Do I just use a normal mortar mix, or is it more likely it be
some kind of render?
You could use a lime mix ... but I have benched many inspection chambers
(even in days when it was Ok to call them Manholes) never needed to use
lime.
... wire brush well at the joint to old benching.
Liberally coat with diluted PVA ( for adhesion, nothing to do with drying)
Mix up a stiff mix of 3:1 with OPC, with some plasticizer in water if you
have it ... if not a quirt of washing up liquid will do.
Apply with loads of pressure to get it into every crack, trowel with plastic
or wood float to avoid drawing out the cement.
When close to set, smooth off with a sponge for finish.
If you need it to set quicker use some rapid set in with water ... but
unless you are due to overflow channel, I wouldn't bother.
Andrew Gabriel
"Rick Hughes" <rick_hughes@remove_me.btconnect.com> writes:
>
> "Michael D" <micha...@hotmail.com> wrote in message
> news:2f214ae7-a540-47d5...@d17g2000yqb.googlegroups.com...
>
>> When I rodded my drains recently I found that the benching needs to
>> be patched in a couple of places in one of the inspection chambers.
>> The inspection chambers appear to be original, installed around 1914.
>> The places that need repair are just above the main flow so get wet at
>> times. I’m got some questions:
>>
>> - Do I just use a normal mortar mix, or is it more likely it be
>> some kind of render?
>
> You could use a lime mix ... but I have benched many inspection chambers
> (even in days when it was Ok to call them Manholes) never needed to use
> lime.
I wouldn't use lime in this application.
(Neither did the Victorians, and the Victorian benching in my
drains is still in perfect condition. Only the more recent ones
have needed redoing.)
> ... wire brush well at the joint to old benching.
> Liberally coat with diluted PVA ( for adhesion, nothing to do with drying)
For this, I would use EVA (sold as waterproof or exterior PVA)
mixed up with cement into a slurry. It will tell you how to do
this tin - it's a standard waterproof bonding method.
Note that waterproof PVA is only waterproof when used with cement.
Ordinary PVA is water soluable.
> Mix up a stiff mix of 3:1 with OPC, with some plasticizer in water if you
> have it ... if not a quirt of washing up liquid will do.
>
> Apply with loads of pressure to get it into every crack, trowel with plastic
> or wood float to avoid drawing out the cement.
> When close to set, smooth off with a sponge for finish.
I'd use a metal trowel, as that gives you the best waterproof
finish.
> If you need it to set quicker use some rapid set in with water ... but
> unless you are due to overflow channel, I wouldn't bother.
>
--
Andrew Gabriel
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