How to seal this cold concrete joint?

[bluedog225]

I’d like to pour a concrete pier on top of this one. To bring the pier top level up to ground level.

What’s the best way to seal this cold joint against water intrusion? It’s located about 5 feet underground. I’ll be placing a sonotube on top of this and pouring concrete.

Ideally, something I can get in a small batch. But I’ll look at anything. There are some bentonite base products. Such as below.

Thanks

 

[rsanter]

Personally I would dig a bit deeper.
I would then clean and chip away at the top of the old concrete to get a clean surface.
then I would use a bonding agent and I would go to the next larger tube size and have the new tube and pier overlap the old by about 4”

 

[The Cobbler]

will it really matter? you don't have any frost to really worry about heaving

 

[bluedog225]

No frost line here (central Texas). But I was under the impression that keeping water off the steel was a good idea.

 

[bluedog225]

Personally I would dig a bit deeper.
I would then clean and chip away at the top of the old concrete to get a clean surface.
then I would use a bonding agent and I would go to the next larger tube size and have the new tube and pier overlap the old by about 4”

This pier is one of four. I’d like them to all behave the same in terms of interaction with the soil (sand/clay). An overlap like that might give rise to differential movement.

 

[PopcornSutton]

A waterstop is used in construction joints to protect water leaking through the joint, where needed, such as a concrete tank or to seal an interior space. For typical construction joints, just a bonding agent is used.

 

[bluedog225]

I’m a little surprised there’s not more concern about water in there.

I’ll chip or grind some channels so the top doesn’t’ actively hold water. Seems a little informal though.

Thanks all.

 

[wssix99]

You don't need to seal that. Concrete is porous and soaks in water like a sponge. Sealing the joint does nothing for you. If the concrete is below the water table or in the dirt, water will get inside the pores.

Regular concrete sets underwater. It loves this.

An above ground joint where water can pool and freeze/expand is a different type of issue. Nothing to worry about here, though.

 

[Jacko264]

I may be wrong but I would just fill the hole with concrete

 

[bluedog225]

You don't need to seal that. Concrete is porous and soaks in water like a sponge. Sealing the joint does nothing for you. If the concrete is below the water table or in the dirt, water will get inside the pores.

Regular concrete sets underwater. It loves this.

An above ground joint where water can pool and freeze/expand is a different type of issue. Nothing to worry about here, though.

I didn’t realize this was the reason for avoiding cold joints.