I encountered an amazing interior wall system while cutting into a kitchen wall (backed to the bathroom). A wet wall 6" studs. House 60-70 yr old. Obviously original construction.

The interior surace is 3/4" thick but composed of two layers. The inner-most layer is a lighter grey, the outer-most a darker grey (concrete color). These two layers are clearly laminated together (not one installed over the other).

Broke a hole with a hammer, and using a new demo-blade in a reciprocating heavy duty saw started to cut straight down. Stripped the blade in six inches. Thinking I had a bad blade tried again. Six inches and the teeth were leveled. Broke the rest out with hammer but kept a section to analyze.

The innermost section is light grey (similar to drywall, ), there are dark specks in the material of both but more in the darker grey. There are highly reflective specks, like glass bits, embedded in both but most in the darker concrete looking layer.

I have never seen anything that will destroy blades like that. Never seen a 3/4" laminated wall.

Job done but need some advice here.

What is this material(s)?

Many thanks to you for your answers here.

I wonder if it could be glass fiber reinforced concrete panels, GFRC, used for exteriors. I think it is often sandwiched too. The glass is lighter than the concrete and metal (rustable) reinforcing isn't needed. One company that makes them is Stromberg.

Concrete with glass chips has some popularity now as kitchen counter material.

Are you sure it's not plaster? Brown coat scratch coat with wire mesh? That will ruin a blade quickly.

PS Join in with joypulv for your help on the panels!

It's definitely not plaster. It's 2 distinct layers bonded by some type adhesive, and each is more dense than plaster. I've torn in to walls in many old houses and have never seen anything like this.