Incremental　load　one-dimensional　consolidation　tests　were　performed　on　dredged　clays　with　and　without　ageing　to　investigate　their　time-dependent　compression　behaviour.　The　dredged　clays　investigated　had　a　wide　spectrum　of　liquid　limits　within　55.6%　to　100%　and　a　predominant　clay　mineral　of　illite.　It　is　found　that　vertical　yield　stresses　develop　notably　during　ageing.　The　developed　vertical　yield　stresses　vary　within　the　range　of　1.2　to　1.8　times　the　specifically　assigned　vertical　effective　stress　under　which　ageing　is　allowed　for　15　to　105　days.　But　the　corresponding　ageing　volumetric　strains　are　small,　varying　within　the　range　of　0.6%　to　3.4%　with　most　being　less　than　2%.　The　test　results　obtained　also　allow　proposing　an　empirical　equation　of　assessing　vertical　yield　stress.　The　changing　law　of　vertical　yield　stress　with　stress　level　for　ageing,　ageing　time,　soil　properties　is　investigated　based　on　the　empirical　equation.　Moreover,　it　is　found　that　the　structural　resistance　of　dredged　clays　developed　during　ageing　for　a　period　of　consolidation　time　up　to　105　days　is　weak　compared　with　the　sedimentation　compression　line　of　natural　clays　developed　during　long　geological　ageing.　But　the　compression　curves　of　dredged　clays　with　ageing　converge　slowly　to　the　intrinsic　compression　line　over　a　wide　range　of　stresses,　like　natural　clays　subjected　to　the　effect　of　soil　structure　developed　during　long　depositional　and　post-depositional　processes.　©　2016　Elsevier　B.V.