I saw this and figured that the skoolies on here would like to see it. You get the look of tiles or pavers without all the cracking, the ends could be cut as thick or thin as needed with just a miter saw, and 2x4s are rather inexpensive. Just seal them and lay them with something flexible and you're good to go.
Bob Villa used this on a project, he called it 'cobbled wood". He used weathered lumber that had check cracks and other imperfections to give it some character. For grout he mixed sawdust and varnish and applied it with a grout float. The tiles were glued using a vinyl adhesive so water in the glue wouldn't affect the wood. The finished project looked great.