2019-12-26 · China siltting wholesale. At the same time of preventing the clay granule from passing, it allows the water and the gas pass through freely. 2 Separation: The isolation of the railway dregs and the roadbed, roadbed and the soft base, surface of the airdrome and parking lot and the groundsill, different dam materials. 4 Protection It prevents the bank from being washed out, protects the bank .