Sealer and sand binder in onebcs is a water based, high grade surface sealer and sand binder for block paving and concrete. It provides a wear resistant coating for concrete and brick surfaces and has been specially formulated for block paving, penetrating the surface and stabilising the jointing sand. Once dried, the sand and blocks are bonded together.using the latest technology, it provides durable surface protection. On previously untreated surfaces, it penetrates and gives a surface coating which will result in the paving having a changed appearance. This would result in a matt or satin sheen to the paving.bcs can be used on a variety of concrete paving materials that may be used to create well drained driveways, paths, walkways and patios.binds the sand between blockshard wearing and long lastingweed resistant