Akmon
An akmon is a multi-tonne concrete block used for breakwater and seawall armouring. It was originally designed in the Netherlands in the 1960s, as an improvement on the tetrapod.
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Wikipedia
An akmon is a multi-tonne concrete block used for breakwater and seawall armouring. It was originally designed in the Netherlands in the 1960s, as an improvement on the tetrapod.