Polymeric sand is used to fill in the joints in between brick pavers. It is a type of sand that is created by mixing fine sand, binders and additives that help lock pavers together in place. It is different than regular sand, because regular sand not only is it missing the additives that help lock pavers in place, but it can also easily be washed off from pavers joints with rain, therefore leaving the joints exposed to moss, weed growth, insects and paver shifting.