It's a mixture of sand and coquina shell that sticks to everything. The majority of the site is actually concrete. The pad is about 20X30 (varies from site to site) and unless you really need to, it's not necessary to use it. We usually pull our coach as far back into the site as we can, leaving more concrete in front. The sand pad has never caused a problem. If needed, I just throw down a mat on the sand pad to keep from picking up the stuff on my shoes and tracking it into the coach.
Premium sites are all concrete and most of them have no area to stake down a tent or dining fly/e-z up.