The melted snow by potassium chloride which was sprayed for snow-removing work percolates into pavement layer through pore on ascon pavement layer. At this time, percolating water stays one point according to slope of concrete Slab upport portion, and stayng water generates black ice with freezing on pavement layer.

※ What is Black Ice?

When invisible thin layer due to raining or snowing on road in winter covers on road, it is called black ice because black ashalt looks transparent. It occurs mainly often at shady road, spur of mountain, beach road and underpass.

If it is installed Slab drain pipe on the upper section of concrete Slab and induced drain with installation of Slab drain (pore pipe) after coating of primer and road film waterprrof material, It prevents black ice anf alkali reaction of concrete Slab upper portion by calcium chloride.