... or glassfiber base 2.Surface material: PE film, sand,mineral,Alu Alu foil SBS/APP waterproof membraneUsage range:Bridge building, storage, road, tunnel ... , no apart ElongationMaximum≥30 40 Secondly-Maximum≥ Oil LeakingPieces≤ 2 Alu foil SBS/APP waterproof membrane