Bridges & Tunnels Duo Duo is a membrane used for infrastructure work. membrane has the same composition as Duo High Tech but comes with extra strong composite reinforcement in the middle. Having granular protection specific to reject the site – cross. Concrete and asphalt layers can be directly applied on top of the membrane without the need for an additional layer of protection. It is extremely powerful and is used where there are extra high demands on a strong waterproofing membranes as well as for open cut tunnel, bridge and car park decks.