Existing Concrete Like Sand

[murphy89]

Found an existing column on a site where you can scrape the concrete away like sand...has anyone ever seen this? What could the cause be? Video is below.

[URL unfurl="true"]https://res.cloudinary.com/engineering-com/video/upload/v1717079368/tips/20230615_162711000_iOS_pvlo4y.mov[/url]

 

[LittleInch]

Not enough cement?

Remember - More details = better answers
Also: If you get a response it's polite to respond to it.

 

[dik]

How old? Some early cements, depending on the source, did not have the proper pozolanic qualities. I've encountered fieldstone foundation walls in early barns and buildings where the 'mortar' has disappeared over time.

-----*****-----
So strange to see the singularity approaching while the entire planet is rapidly turning into a hellscape. -John Coates

-Dik

 

[JAE]

Heavy chloride exposure, over time, can turn concrete into a sand-like powder.

 

[HTURKAK]

Apparently this is buried concrete. The concrete surface should be protected against aggressive soils , with a few measurements ( external bitumen epoxy paint , membrane protection , the use of SR cement..)
In this case , my opinion is sulphate and salt content of the soil is the reason.
Probably 5-7 cm interior could be still intact .

I have seen similar case in KSA at buried concrete elements.



He is like a man building a house, who dug deep and laid the foundation on the rock. And when the flood arose, the stream beat vehemently against that house, and could not shake it, for it was founded on the rock..

Luke 6:48

 

[LittleWheels]

I agree that sulphate attack is most likely with salt another possibility.

Thaumasite has been a big problem in some parts of the UK but the OP's instance might be conventional sulphate attack..

https://www.icevirtuallibrary.com/doi/abs/10.1680/rraeoc.31753.0014

 

[murphy89]

Thanks! The column was buried so sulfate attack sounds reasonable. Would this happen even to concrete that is the proper exposure class for chloride exposure? Or is it a sign than the wrong exposure class was used?

 

[LittleWheels]

We don't know enough to make further useful comments. What is the actual environmental exposure, rather than assumed? What is the aggregate reactivity? What is the actual mix design/ cement blend?