What's this under my kitchen flooring?

[superdon]

Had a leak a few months ago and shortly after, noticed something odd under the flooring. It got worse and worse over time.

Peeled back the flooring and found this?!? It's like a cardboard tube filled with concrete that's spilt open. Very odd.

It's about 5 or 6 inches wide, about 10 feet long. A Victorian terraced house.

Any ideas?

 

[JohnD]

I remember large cardboard tubes having pipes run through them. I thought it was for insulation. Can you scrape out some of the fragments and see if there's anything indide?

The cement/concrete looks relatively modern, will not be original to house.

 

[ree]

OP,
You had a leak from where?
Do you have or have you had UFH - supply pipes - or waste pipes under what looks like very dry SLC?
Why not lift all the sheet vinyl & then examine the floor?
You could remove all the mess from the floor chase & make good with sand & cement? But you would need to follow the chase and clean it out of debris & cardboard before any S&C infill.

 

[superdon]

It was a small leak from a dishwasher. We are certain this is what caused this as you can track the water.

Definitely no under floor heating. We've been here for 20+ years.

Worry is, if we repair this, what else might happen?