Effects of organic matter on mechanical properties of dredged sediments for beneficial use in road construction.

In France, the road construction sector is the greatest consumer of granular materials, with a yearly consumption of about 200 million tons. With the shortage of standard materials, the valorisation of dredged sediments for road construction could constitute an interesting solution. Dredged sediments generally consist of a mineral phase, an organic phase (in various forms) and a liquid phase (water). The presence of organic matter (OM) in sediments, even in small amounts, affects their engineering properties. The main objective of this study is to investigate the effects of organic matter content on the engineering properties of dredged sediments. For this purpose, a specific methodology to reconstitute samples with different amounts of organic matter contents is proposed. The evaluation of the effects of organic matter content in term of compressibility, shear strength, compaction and bearing capacity show that even for high amount of organic matter the performances of the studied samples are compatible with the use in road construction sector.