Flooded trenches

[b21playa]

Hi all

Dug out footings a few weeks ago for a new retaining wall in the garden. Just before we were going to pour concrete it rained constantly and since it’s been full of 4” of water.

I’ve Pumped the water out and walking in trenches it’s soft, like walking in wet concrete. Any advice of what to do, wanted to get concrete poured. Ground is clay

thanks in advance for any info

 

[Alastairreid]

The concrete will displace the water in the trench.

 

[b21playa]

The concrete will displace the water in the trench.

Not much water left now, just concerned about soft base now, my foot sinks in

 

[JohnD]

I have only come across this incidentally, but the practice was (on the day concrete is to be poured)

pump it out

scrape out the soft mud from the bottom of the trench

pour a drylean mix into the trench and compact, to absorb remaining moisture and give a clean bottom

Pour the main mix.

 

[frutbunn]

I have only come across this incidentally, but the practice was (on the day concrete is to be poured)

pump it out

scrape out the soft mud from the bottom of the trench

pour a drylean mix into the trench and compact, to absorb remaining moisture and give a clean bottom

Pour the main mix.

Thats how I would deal with it if I was inspecting it.

 

[JohnD]

it's the standard instruction on the plans for substations.

I followed it when replacing a leaking drain.

 

[b21playa]

Thank you.

I’ll leave it until Saturday morning and scrape out soft clay

 

[b21playa]

Hi all

is it worth putting rebar in the footings or prefab cages?

 

[noseall]

Hi all

is it worth putting rebar in the footings or prefab cages?

No. They will achieve nothing. Your best bet is to get rid of the soft stuff just prior to the pour.

 

[b21playa]

No. They will achieve nothing. Your best bet is to get rid of the soft stuff just prior to the pour.

Perfect, thanks for that. Let’s hope the soft stuff isn’t too deep

 

[frutbunn]

Hi all

is it worth putting rebar in the footings or prefab cages?

Not normally unless you are bridging over soft spots, capped of wells,changes in sub soils (ie changes from clay to sand) etc. I used to work in an area where there were abandoned mine workings and it was used very extensively.

 

[b21playa]

Not normally unless you are bridging over soft spots, capped of wells,changes in sub soils (ie changes from clay to sand) etc. I used to work in an area where there were abandoned mine workings and it was used very extensively.

It was all hard until Undisturbed clay until the rain we had and trenches sat in 4” of water

 

[frutbunn]

It was all hard until Undisturbed clay until the rain we had and trenches sat in 4” of water

No need for it but it won't do any harm either

 

[b21playa]

If not needed I’ll just dig out soft bit and get concrete in

 

[b21playa]

Thanks again for the advice, managed to dig out trenches and lay 7 cubic meters this afternoon.