What determines the choice between rock and concrete as armour layer?
For design wave heights below 3 m [significant wave height], rock is often economically viable for use as armour layer. For design wave heights above 4 m extremely large rock sizes are required which are difficult to obtain, handle and place. Limited availability of such material leads to greater expense. In areas where good quality rock is difficult to obtain concrete armour may also be preferred for smaller wave heights.
