At the American Concrete Institute Fall 2015 Convention in Washington D.C. I delivered a presentation entitled “Particle Packing from a Rock’s Perspective”. ACI has just posted the presentation on YouTube at . If you are looking for a stuffy presentation filled with facts and figures, this presentation isn’t for you. If you want to find out what rocks think about particle packing, drop by and meet Rocky. Hey, its only 12 minutes long. What can you lose?