Every year, significant volumes of marine sediment are dredged from the harbour of Dunkirk, France. These materials may in fact be used beneficially in the composition of new concrete accropode blocks to protect the harbour coastline. This paper evaluates the mechanical behaviour and durability of accropode blocks composed of concrete and dredged fine sediments after three years of storage on a dock at port of Dunkirk. A description of accropode blocks, a coring campaign and characterisation of cylindrical core samples are presented and discussed. To assess the durability of the concrete, a battery of accelerated tests is performed. The mechanical properties of various core samples are measured during durability tests using non-destructive techniques. The results suggest that sediment addition should be limited to 12.5% of the concrete mix to ensure the integrity of mechanical properties under external sulphate attack and frost action. © 2019