Swell-shrink behaviour of cement with fly ash-stabilised lakebed sediment

Abstract

Dredged river or lake sediments are ideal for repurposing in engineering applications. Unfortunately, the low strength of these materials makes it necessary to amend them with chemical stabilisers before utilisation. This research attempted to improve the shrinkage and swelling potentials of cement-stabilised dredged sediments by addition of fly ash (FA). Material mixtures were created from combinations of sedimentary soil from Phayao Lake in Northern Thailand, Ordinary Portland cement (OPC) type I, and FA. Mechanical tests determined that the unconfined compressive strength of cement-stabilised sediments with 7% and 10% OPC increased with the addition of 25% FA. Digital imaging technology and free swell tests determined that the 3D volumetric shrinkage and swelling of OPC-stabilised sediment reduced by 40% and 2.8%, respectively, when 20% FA was added. With this additional OPC and FA, the treated sediment satisfied both strength and durability criteria for reuse as road material as set by the Thailand Department of Highways.