Hello,
A bit of a long question, sorry, but I am almost completely ignorant of
this topic.
I have recently been on what is appearing to be a half-cocked job to
stop leaks in a tanked cellar.
During heavy rain when the ground water level rises, there would be
water ingress. Much misery. Most of the problems have been sorted, but
there are two repairs which seem a bit suspect to me.
I chipped out the old cement which seemed to be little more than sand,
and dug out a bit of what was behind it. The holes are about 4 inches in diameter, and 4 inches deep for one, 6 inches for the other.
I cleaned the cement with acid and rinsed properly, the surfaces were
clean. Then I brushed on some SBR. I made up the repair mortar with SBR following the instructions on the container.
There were five repairs in total. Three have dried fine and since shown
that they are waterproof.
The other two seem to be having trouble actually drying out but do not
let any water through, there is no puddling of water.
I ran a fan (not heated) over the repairs and after twenty minutes or so
they appeared dry but a few hours later the dark wet-look was back.
I will link to two photo's demonstrating this on the deeper of the
repairs (hosted on google photo's 1920 x 1080 in size, no adverts that I
know of, if any are seen they will have been automatically inserted by google):
https://photos.app.goo.gl/eKsMBb2T9aruCvk4A
This shows the damp looking patch but the surrounding mortar looking dry.
https://photos.app.goo.gl/d9czDorHDq6NLEmR9
This shows the dryer look after a few minutes of fanning with unheated
air. The dark line around it is, I presume the SBR seam as it appears to
be the same colour as other areas of the cellar I have painted SBR on.
Please don't be too envious of my excellent cement smoothing skills.
On both photo's the larger darker arch above the mortar is dries SBR and
not damp.
The damp looking patches don't feel damp, or at least they don't feel
damp *to me*, but the lingering wet look makes me wonder.
So is this something which will need to be re-done, or can I paint over
it with floor paint? I am not particularly concerned about the looks of
it, I just don't want to paint it and then the damp causes something to
fail in future.
Thanks in advance for any info or advice.
On 06/04/2025 14:02, Tricky Dicky wrote:
Cement “sets” by a chemical reaction not by drying out. Concrete for
instance will set under water, it might not achieve the strongest bond but >> will set.
Thanks, yeah, I am aware of that but will it prevent moisture passing through,
and how long should it take to cure?
On 6 Apr 2025 at 21:40:35 BST, David Paste wrote:
On 06/04/2025 14:02, Tricky Dicky wrote:
Cement “sets” by a chemical reaction not by drying out. Concrete for >>> instance will set under water, it might not achieve the strongest bond but >>> will set.
Thanks, yeah, I am aware of that but will it prevent moisture passing
through,
IIUC, even when cured completely it's unlikely to be an effective 'tank'. It depends on the pressure behind the cement render, but overall, moisture will try to push through at the point of least resistance. That may (or may not) be
the cement. I can't see an inch or so of anything being that effective in a cellar - moisture will push through at some point, either through the material
or at a join.
and how long should it take to cure?
On 07/04/2025 04:51, RJH wrote:
IIUC, even when cured completely it's unlikely to be an effective 'tank'. It >> depends on the pressure behind the cement render, but overall, moisture will >> try to push through at the point of least resistance. That may (or may not) be
the cement. I can't see an inch or so of anything being that effective in a >> cellar - moisture will push through at some point, either through the material
or at a join.
Cheers. The reason I started this was because the thickness was less
than an inch in a few places, so I replaced it with more, about 3 to 4 inches.
On 07/04/2025 11:49, The Natural Philosopher wrote:
The ability of concrete to resist water is dependent on theamount of
cement in the mix.
water will not penetrate 100% cement or stone but will penetrate 100% sand. >>
The key is enough cement to fully fill the interstices between sand grains
Thanks. The SBR container advised 4:1 sand to cement. I have been told
this is "normal" for mortar in a brick wall, but now I am thinking that
it might not be good enough for my use, even with the SBR.
Frustratingly, in another area, I mixed up 4:1 and added PVA from advice
on a youtube video by a swiming pool repairer - I have since learned
that SBR is preferred because once it dries it won't remoisten whereas
PVA does, but the PVA mix has worked an absolute treat.
That is why concrtete ships worls
There's a few of them abandoned on a bit of the ship cannal near here.
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