Strength and deformation properties of Dunkirk marine sediments solidified with cement, lime and fly ash

Abstract

Most of the previous studies concerning solidification of dredged sediments focus mainly on the strength and environmental properties, but the deformation properties have not been fully appreciated. The present study emphasizes the deformation characteristics of marine sediments by using deformation parameters. A series of unconfined compression tests was performed on about 150 standard samples of 13 designed mixes. After analyzing the stress–strain curves of different mixes at 14, 28, 60 and 90days, the effect of binder content (as cement, lime and fly ash) on peak strength and failure strain is discussed. It can be found that addition of fly ash improves the mechanical performance of lime-treated sediments, but damages the strength of cement-treated sediments. The lime-fly ash binder can substitute lime and cement-fly ash binder to solidify sediments owing to lower cost, waste recycling and good ability to gain strength. The concept of strength ratio is introduced to evaluate the development of unconfined compressive strength with curing time and binder content. By comparison, the relationship between failure strain and unconfined compressive strength is calculated as σ=(20–130) εf and the failure strain ranges mainly between 1% and 2%. The deformation modulus defined at 50% of peak strength is explored for designed materials at different binder contents and different curing times. The development of deformation modulus is in accordance with unconfined compressive strength. A quantitative correlation E50=119.91 UCS is therefore determined according to large quantities of test results. Finally, the microstructure of solidified sediments is observed by using scanning electron microscopy.