Pouring new concrete onto existing concrete

ArchXStanton

Hi All, the path around my house has sunk around an inch or 2 down from the house and its fairly rough in places, ants and other bugs are starting to get into the house through the gaps it's leaving.

I have it formed up to pour another layer of concrete on it(about 2 inches) , I'm just wondering about it bonding to the existing path, I've drilled holes in the existing path and I've got PVA bonding here, does anyone know if you just apply it to the existing concrete or do I have to put it in the new concrete mix as well?

Thanks in advance

BryanF

Is the path finished sinking?

Who2

Your new path is nearly guaranteed to crack. There’s a plaster typerender that can be used in situations like these that can be troweled on and finished to whatever look you want. I can’t think of the name of it but it can be built up to 2 inches but has good bonding and movement so you won’t have the cobweb type cracks your going to get by putting concrete over concrete.

ArchXStanton

BryanF wrote: »

Is the path finished sinking?

I'd presume so, it's there 33 years to get to this point

ArchXStanton

Who2 wrote: »

Your new path is nearly guaranteed to crack. There’s a plaster typerender that can be used in situations like these that can be troweled on and finished to whatever look you want. I can’t think of the name of it but it can be built up to 2 inches but has good bonding and movement so you won’t have the cobweb type cracks your going to get by putting concrete over concrete.

I was going to do a strong concrete mix on it, do you think it will make a difference?

Who2

ArchXStanton wrote: »

I was going to do a strong concrete mix on it, do you think it will make a difference?

No, it will probably crack more if too strong. If you are going to chance it I’d try and layer in a mesh, something like extremely big scrim tape. It might help. I’d try to ensure expansion joints are directly above existing ones as well. I’m no expert on concrete but done wrong it’s a mess.
Did you consider putting in limestone or sandstone slabs?

ArchXStanton

Who2 wrote: »

No, it will probably crack more if too strong. If you are going to chance it I’d try and layer in a mesh, something like extremely big scrim tape. It might help. I’d try to ensure expansion joints are directly above existing ones as well. I’m no expert on concrete but done wrong it’s a mess.
Did you consider putting in limestone or sandstone slabs?

No didn't consider it, I drilled holes in the existing concrete about 15 inches apart for the new concrete to grip into. I'm thinking the mesh would be a good idea aswell

kieran.

If the path is sinking putting more concrete is just going to add to the weight which will in turn acelarate the sinkage?

Dig it all out get a good base of terram and hardcore in and then concrete.

Do it right first time !

SC024

ArchXStanton wrote: »

Hi All, the path around my house has sunk around an inch or 2 down from the house and its fairly rough in places, ants and other bugs are starting to get into the house through the gaps it's leaving.

I have it formed up to pour another layer of concrete on it(about 2 inches) , I'm just wondering about it bonding to the existing path, I've drilled holes in the existing path and I've got PVA bonding here, does anyone know if you just apply it to the existing concrete or do I have to put it in the new concrete mix as well?

Thanks in advance

Scabble it with a toothed kango bit to roughen it up & provide a key for new concrete, ensure there is no moss/algae etc on existing paths & then a strong coat of polybond / SBR bond would be better & then mix same through the new concrete, leave expansion joints directly above & in line with the existing ones.

Calahonda52

Dig it out.
You don't know what is causing the subsidence, so you need to find out.
Any remedial work is just a fantasy.