It will be a near exact match.
Replace concrete sidewalk section.
This condition was either caused by too much water in the mix or exposure to heavy rain before curing.
Step 4 replace the damaged concrete sidewalk section.
Long by 3 1 2 ft.
If you can use the same concrete for the new sidewalk section as was used for the others it will dry and cure relatively the same.
The surface of the existing concrete had deteriorated to dust and loose aggregate.
Use the rake to mix the concrete to an oatmeal consistency.
Either way the section was disintegrating and had to go.
To replace the damaged concrete the existing section must be safely broken up and the underlying foundation properly prepared before you can pour new concrete.
I saved myself time and a boat load of money by repairing it by myself.
Have a concrete sidewalk you are trying to repair cheap and easy.