watertight concrete mix

[rsk1]

my kitchen wall is a retaining wall above which there is a small concreted yard. At the moment the yard slopes toward the kitchen, I need to resurface it so that it sheds away from the wall. Will a "normal" mix of 1:2:4 do, or should i be looking at a stonger mix eg. 1:1.5:2.5 to get more watertightness?

 

[^woody^]

Typically you would need to increase the fines (the sand) with a slight increase in cement to allow for this, possibly include an additive, vibrate it to get the air pockets out and then give it a nice trowelling to seal the surface.

 

[tomfe]

There is a bit more to a real water tight mix design, you need more a fines, a lower water content so a plasticiser, this will help with compaction and close the pores.
Are you sure you wont get hydrostatic pressure on your wall?

 

[rsk1]

Are you sure you wont get hydrostatic pressure on your wall?

what do you mean?

 

[tomfe]

As your kitchen wall is your retaining wall, this could get water pushing it's way through regardless of what you do with your yard.

 

[rsk1]

As your kitchen wall is your retaining wall, this could get water pushing it's way through regardless of what you do with your yard.

yes , there's not a lot i can do about that . But at the moment the yard drains toward the wall where there is a drain right next to the wall which is basically not working, so water seeps through the wall. As a first step I want to block off this drain and send the water elsewhere, away from the wall

 

[John D v2.0]

I'm not a builder, but since it's just a yard, could you lay a subbase if required, apply sand and then a dpm sloping towards a drain and lapped up the wall a bit? Then the concrete on top to whatever specification you like and it won't matter if it gets saturated.

 

[JohnD]

But at the moment the yard drains toward the wall where there is a drain right next to the wall which is basically not working, so water seeps through the wall. As a first step I want to block off this drain and send the water elsewhere, away from the wall

You have a faulty drain?

Dig it up and mend it.

 

[Ian H]

Or dig it up and move it outwards to a suitable place.

 

[rsk1]

You have a faulty drain?

Dig it up and mend it.

that is one option, but i would prefer it if water sheds away from the wall all together, so that it the drain can't go wrong again in the future