... underground construction such as tunnel, subway, basement ,roofs and pools etc. 1. The special formulation of fire ... base surface must be clean,solid,level,dry;no grit,rift and loosing dust. For a large recess ... ,fill it with cement mortar and then level it. Remove the protrusion and clean dust.If working on ... a solid and flat state.Before the membrane is cool, seal the edge of joint by float. 4. ...