Muriatic acid is commonly available e g from pool suppliers and is dilute hydrochloric acid.
Dissolve concrete in pipes.
The croc crete product will dissolve the blockage to then easily clear.
How to clear concrete from drain pipes.
It is a slow process.
There are a variety of mechanical tooling to break and remove concrete from inside a pipe.
Easily dissolve concrete grout levellers screed cement products in drain pipes and drain traps.
Common problems this technique has is getting the tool to the concrete if the pipeline has multiple bends before you can access it and also the damage caused to the host pipe when using the mechanical tooling to break and remove the concrete.
Being able to successfully clear concrete from drain pipes is a common question for drain clearing and pipe relining contractors.
I once had my electrical concrete embedded plastic conduit blocked with concrete.
Ways to clear concrete from drains.
His advice to get the pipe fully clear was to use hydrochloric acid and allow it to sit in the pipe to soften the concrete so it could be flushed through the pipes.
Cctv inspection and high pressure jet blasting.