Sealing rough joins in concrete

[reb78]

We have put stables in one of our barns. Basic construction is a 45'x35' concrete slab which is laid in rough sections. Inside the edge of Around the edge, there is a raised square of shuttered concrete about 5ft in from the back and 1ft in from the exposed side (they used ballast/sand mix for this) and the sides of the shed run down the outside of this continuous block. I have sealed where the shed sides meet the concrete slab with a fine sand/cement mix as i was convinced that the use of ballast for the shuttered area meant that water was seeping under it where the ballast had left small gaps with the concrete base beneath. I have also put gutters up as there were none so all roof water was running onto the concrete outside of the shed.

Some water is still getting in and I think it is running into the rough joins in the concrete slab and seeping in inside the shed.

Should I just grind out a the join and re-fill or would a mastic (?) sealer or other concrete sealer work?

Not sure if I have explained this well, I can get some pics, but it is pouring down at the moment!

 

[RonA]

Most of the concrete to concrete gaps Ive seen have been filled with bitumen.
RonA

 

[God mode restorations]

Most of the concrete to concrete gaps Ive seen have been filled with bitumen.
RonA

Yes. Bitumen. Done loads of over the years

 

[Pete.]

Temporarily you can pour a line of cement around the kicker and trowel it to a fillet. We make temporary water bunds like this all the time, it works great for holding back an inch or two of standing water.

 

[reb78]

Temporarily you can pour a line of cement around the kicker and trowel it to a fillet. We make temporary water bunds like this all the time, it works great for holding back an inch or two of standing water.

I think I have done this if what you are suggesting is what I think I have done! My worry is that it is seeping into the cracks between the joints in the base slab and seeping in there.

For the bitumen, would this be the sort of thing I could use?? Or do you mean something else?

https://www.everbuild.co.uk/product/903-bitumen-trowel-mastic/

 

[PhillipM]

polyurethane works well too

 

[weldingnovice]

I have always used this stuff for construction/expansion joints in concrete and masonry. Have to use a pointing type gun with it though.
Sticks like 5hit to a blanket used it as seem sealer on the van better than the other stuff I have seen used.

 

[Pete.]

You could use the paint-on black jack, they use (or used to) that to paint retaining walls where the ground will meet the wall to keep the damp from getting through.

Here's an example of what we use on site, this is holding back about half an inch of standing water but it was much deeper when it rained hard. We had stripped off a building facade on a terraced roof and needed a temporary way to stop standing water running into the building whilst they built a new one. We poured a line of straight cement on the floor and trowelled it into a peak. Did probably 120 metres of this and none of it leaked. It looks damp the other side but that's just where people were tramping through it.

The contractor though it wasn't very professional-looking so he had some of it removed and replaced with screwed-down timbers wrapped in felt. Looked very smart but the water ran straight under it so they had to put the cement down again.

 

[Anguz]

Sika is good stuff.... we use it on the joins in concrete water tanks... does not have to be dry to apply

 

[macandmoss]

Don't know about bitumen in the stables as horse p*ss is very acidic and I don't know if it would effect it ,don't have the horses anymore and mine are empty now . I would maybe cement fillet it and maybe try tanking slurry on top instead of the bitumen , just an idea

 

[Dcal]

Another + for Sika / polyurethane.
The fact that it's flexible means it's great for movement joints.

However if you are applying a sealer you should try and make the slug of polyurethane twice as wide as it is deep.
This is so that it can flex without pulling of the concrete. If it's very thin, in he relation to the depth, it may de-bond because the sealer is now too stiff.

If you fill the joint with foam rope, or whatever, then apply the sealant like in the sketch below, which is copied from the Fosroc MS600 data sheet. (Which will also work, but as it really needs a primer for the concrete I would stick with the Sika)

Also note in the sketch the sealer is red and the backing foam is orange.

 

[knighty]

what's the ground like outside the shed, around the outside edge of the shed concrete ground slab?

is the ground height below the concrete hight?

if there's no drainage there, then water will come up from under... and any water getting on top of it will have no where to go

I'd dig out a small trench around it, only needs to be 6 inch wide 6 inch deep (below concrete level... bu deeper is better), all the way around and see what that does

if it helps dig it a bit wider/deeper (depending on conditions etc.) and fill with with gravel/stones/whatever

 

[reb78]

I thought some pics might help - they tell the story. See if you can come up with what the problem is. Whenever it rains, the floor on the inside of the shed gets very wet - its not driving in as the back of the shed faces the prevailing weather (unless the wind is from the north). The side clogs up with leaves, but its quickly and frequently cleared. You can see the slab and the shuttered square section set on top of it in the circle. The outside of the shed goes down to the ground level on the outside edge of this. I have run a fillet of concrete around between the outside of the shed and the slab, but it hasnt stopped the water seeping in. I dont think it gets above the level of this fillet. There is a picture that looks like i took a pic of the floor - this is where two sections of the slab meet each other - they are rough, but it was originally just meant for storage so i dont know if anyone really cared how they were laid.

 

[knighty]

I should preface this by saying I'm no expert.... but....

it's dug into a hill leaving the embankment at each side? - if that ground all gets wet and drains away to lower ground, the water could easily drain to under the floor where it'll quickly flow through the hardcore/floor foundations and up through any cracks?

it really needs some kind of brake there, a trench dug out, maybe a bit like a french drain? (a pipe with holes in it in a trench with gravel around it)

is there some soft ground at the same level as the stables close by? - you could dig a hole and see what happens when it rains... see if the hole fills up with water? - a little puddle in the bottom would be normal... much more and that's your problem, the water level in the ground is too high all the time or just when it rains?

there could be other stuff going on which digging a hole would help you figure out

 

[addjunkie]

I should preface this by saying I'm no expert.... but....

it's dug into a hill leaving the embankment at each side? - if that ground all gets wet and drains away to lower ground, the water could easily drain to under the floor where it'll quickly flow through the hardcore/floor foundations and up through any cracks?

it really needs some kind of brake there, a trench dug out, maybe a bit like a french drain? (a pipe with holes in it in a trench with gravel around it)

is there some soft ground at the same level as the stables close by? - you could dig a hole and see what happens when it rains... see if the hole fills up with water? - a little puddle in the bottom would be normal... much more and that's your problem, the water level in the ground is too high all the time or just when it rains?

there could be other stuff going on which digging a hole would help you figure out

Have to agree a good foot deep trench all the way round to take water away, my shed is built in to similar level ground, has the drain round the back and one side. If its really wet I see water seeping from under the slab on one side. Probably made worse as we have almost no soil, only clay.

You could cut the slab edge with a still saw and beak out a 6 in trench all the way round, to save digging the land back. But either way itll be awkward due to the shape of the ground.

 

[weldingnovice]

I wouldn't expect the mortar pointing joint between slab and panelling to be too effective, would probably slow down ingress of water prior to gutters being fitted.

Agree with others that some water will be coming from areas of raised ground levels around the building.

Removing the pointing halves length of joint pressure wash, priming and sealing the junction between slab and wall panel with polyurethane sealant, don't know what type of gap you will expose there though.

You may have to drain the land around the building as it is not easy to see but the water could be coming up through joints in the floor slab, was a damp proof membrane installed as part of construction?

 

[knighty]

View media item 10131
if the water table neat the building is above the ground level of the building then no amount of sealing the joins will work, at a minimum it'll always be damp, the water will always be trying to push up and out

maybe you're ok during a dry spell, it evaporates faster then it comes up through, but as soon as it rains and comes through faster you'll have puddles


you really need a trench between the building and the embankment, dig it down, perforated drain pipe in it and then fill it with gravel on top to let the water drain into it. bottom of trench/pipe needs to be below the ground level in the stables... doesen't need to be loads, 6inch will be enough (but obviously more is better)

gets a little tricky if there isn't a drain handy - I should have asked that earlier!.... is there one?

 

[addjunkie]

Wrap the polly pipe, or line the trench with weed membrane, keeps them clear longer.

Line trench with weed membrane, some gravel, polly pipe, more gravel, them close the top with the weed membrane, then cap off with more gravel.