Yes, you can definitely fill cinder blocks with concrete. In fact, it's a common way to use up leftover concrete and make something useful out of it. However, you should be aware that not all cinder blocks are created equally. Some are designed to be filled with concrete while others are not. So before you go filling up all your cinder blocks with concrete, make sure you check the manufacturer's recommendations to see if it's safe to do so.

Yes, you can fill cinder blocks with concrete. This will create a solid and stable foundation for a variety of projects, from building a deck to creating a garden wall. Be sure to follow the manufacturer's instructions for your specific cinder block to ensure that the weight of the concrete is safely supported.