Where can I get cylinder concrete?

You may be able to get them from a construction site or precast concrete company. With most projects where concrete is being poured in large amounts it's a requirement to take compression strength samples several times a day. There usually is an abundance of samples that withstood the crush test.

Concrete Test Cylinders For Sale

If you go to a redi-mix company, you can buy some of the core sample cylinders. Mix up a batch of concrete, fill the cylinder, tap the sides, let it cure for a few days, then cut the cylinders off. Most concrete companies will have any of the materials you need to do the job. Hope this helps.

where can I get all ready poured concrete cilnders that did not pass the testing phase

ready mix company ( they test their own ), testing/engineering company ( they sample & test concrete pours )