Fixing TV on concrete behind drywall
You need to attach the mount to the concrete, not the drywall.

There are special anchors for concrete. Most are made of metal and expand into the hole drilled in the concrete with a hammer drill and a masonry bit.

Most masonry anchors are sleeve anchors and use bolts (also called machine screws) to expand the anchor.



There are also metal lag shields that use lag bolts (heavy duty screws) to push outward on the hole and hold the device. These are fairly reliable, but are less forgiving if you need to remove and reinsert the bolt.



There are also masonry screws that can hold in concrete without a separate anchor, but these need precise drilling and care when tightening to prevent stripping the hole.  While they are fine for things that use numerous attachment points, such as studs in a concrete floor or wall, the risk of failure on a device that only uses a few mounting points make these a bit more risky (in my view - contrary points of view welcome!).



The instructions packed with the mount often recommend which size of bolt or screw to use, and many come packed with mounting hardware for masonry attachment.  Drill the size hole called for by the particular anchor, and take care to drill straight and not oversize the holes.

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