Cold joints in walls

[gavztheouch]

I thought I’d start another thread to discuss cold joints in icf walls. Cold joints being the join between one layer of concrete and another layer added after the first layer has set up hard. If like me you are considering pouring your own icf but want to only pour 2 or 3 courses at a time you might end up with more cold joints than normal.

 

my thoughts and research are that then are generally ok of if you plan carefully where they occur. Ie. don’t pour to Just over a window height and then stop shy of completing the full lintel depth above the window.

 

it seems a lot of icf suppliers and contractors don’t use steel reinforcement above grade. Unless it is for above a window for a lintel. So I was thinking if you add in plenty of horizontal and vertical rebar into the wall this should add plenty of strength to compensate for the fact that you have a cold joint. Taking it a step further you could use galvanized rebar to prevent moisture working its way in through the cold joint and rotting the steel.

 

Another Benifit of pouring in smaller lifts is the ability to easily work the concrete and vibrate it well so it’s compacted and well coated around the steel.
 

The downsides are extra cold joints, more pours days and concrete pump hire costs. Unless you can use an alternative method of moving the concrete to the wall. For example a digger with a concrete bucket.

 

 

[Alexphd1]

Quick question, how many cold joints are there in a normal 150mm concrete block (block layed on side) wall?? 

[Russell griffiths]

I cannot see any logical reason for wanting to do more pours than you need to, my first pour was at 2.7 then the next was at finished height, I used lots of starter bars placed in the first pour 600mm apart, I also put vertical bars at all door and window reveals. 

 

If a concrete pump is going to cost you £600 you will waste a lot of money messing about doing little pours. 

As for the digger bucket idea, just forget that right now, do it right use the proper kit and do it like a professional would, hire a pump job done. 

[gavztheouch]

13 minutes ago, Alexphd1 said:

Quick question, how many cold joints are there in a normal 150mm concrete block (block layed on side) wall?? 

Plenty, one of the reasons I prefer icf. 
Did you use rebar in you walls?

Edited September 9, 2020 by gavztheouch

[gavztheouch]

2 minutes ago, Russell griffiths said:

I cannot see any logical reason for wanting to do more pours than you need to, my first pour was at 2.7 then the next was at finished height, I used lots of starter bars placed in the first pour 600mm apart, I also put vertical bars at all door and window reveals. 

 

If a concrete pump is going to cost you £600 you will waste a lot of money messing about doing little pours. 

As for the digger bucket idea, just forget that right now, do it right use the proper kit and do it like a professional would, hire a pump job done. 

My dad did a basement for a friend using his digger and a wide bucket. There is also a good blog on here where a contractor used a bucket/hopper attached to a crane to fill the walls, looked quite efficient and controlled. I won’t say most cases would benefit from these methods though. Just think I have the space and time to do it this way and it might be less stressful and more enjoyable. Just trying to figure out if the end result/ product would be flawed In some way.

[Vijay]

11 minutes ago, Russell griffiths said:

I cannot see any logical reason for wanting to do more pours than you need to, my first pour was at 2.7 then the next was at finished height, I used lots of starter bars placed in the first pour 600mm apart, I also put vertical bars at all door and window reveals. 

 

If a concrete pump is going to cost you £600 you will waste a lot of money messing about doing little pours. 

As for the digger bucket idea, just forget that right now, do it right use the proper kit and do it like a professional would, hire a pump job done. 

 

Absolutely agree with every single word!!

[Russell griffiths]

A concrete hopper hanging from a crane will hold probably 1/2 a cubic m, a digger bucket will hold nothing like that, you will also find that the amount of slop you loose out the sides will be bad, you will also find an excavator has very little height so any wall over 1.8m high will be awkward to reach. 

Sorry unless you are on a remote island where you are hand mixing and filling you walls with buckets then it’s just not worth considering. 

 

You will I’ll also have 30 minutes to unload a concrete truck before they start charging you waiting time so trying to fill an excavator bucket is a non starter. 

[Rmawdsley]

1 minute ago, Russell griffiths said:

A concrete hopper hanging from a crane will hold probably 1/2 a cubic m, a digger bucket will hold nothing like that, you will also find that the amount of slop you loose out the sides will be bad, you will also find an excavator has very little height so any wall over 1.8m high will be awkward to reach. 

Sorry unless you are on a remote island where you are hand mixing and filling you walls with buckets then it’s just not worth considering. 

 

You will I’ll also have 30 minutes to unload a concrete truck before they start charging you waiting time so trying to fill an excavator bucket is a non starter. 

Plus if the 2 of 3 course pour your proposing doesn’t equate to a full load you will get a part load charge which can be £50+ for every cube not carried.