Sika's Post Fix replaces two 50-pound bags of concrete with a mix-and-pour formulation that expands like magic in just minutes. The small, self-contained package includes a two-component mix that activates without water when the internal seal is burst. With the two components thoroughly combined, installers can pour Post Fix into the post hole to secure fence posts, light poles, mailboxes and other non-structural posts of a variety of material including steel, wood, and PVC. An initial set takes place in just three minutes, with just 2 hours to a full cure. The mix is not labeled for structural components such as deck posts. Find Sika Post Fix at Home Depot for about $11.