Heavy and/or persistent wind and water (rain, ice or snow) are commonly responsible for forcing sand out of the joints between pavers, especially if the sand wasn’t compacted very well. It also sounds like your patio gets a good deal of traffic, which can contribute to the problem as well. Fortunately, the solution is simple. The next time you replace the sand, use one that contains a polymer, which is basically an additive that allows the sand to harden and bond the pavers together. QUIKRETE® Power-Loc Jointing Sand and QUIKRETE® Polymeric Jointing Sand are readily available around the country and easy to install. Sweep the sand into the paver joints and dampen with water. Once the sand dries it will create a solid patio that will resist future erosion caused by wind and water as well weeds and insects.