Levelling 2 concrete floors together!

[Kenny600]

I have recently knocked 2 rooms into 1 and as such the floor level at the access point is slightly out.
There is between a 10-20mm height difference.
The largest area is generally level as it was part of a recent extension, and is only the access which is slighty raised off this floor.

I woudl really liek not to have a step or a hump walking in and out of the room so would like to level this where I can. Only I am at a loss of how to achieve this.

Any thoughts from you learned folk?

Thanks in advance Ken

 

[Deluks]

Depending on size.

Chop it out and redo it.

Angle grinder with a stone grinding disc (messy)

Self levelling compound the lower areas to bring it all up.

 

[Chukka63]

Depending on size.

Chop it out and redo it.

Angle grinder with a diamond grinding disc (messy)

Self levelling compound the lower areas to bring it all up.