Experimental Evaluation of Strength Characteristics of Stabilized Dredged Soil

A composite geomaterial (CGM) is developed using dredged soil, bottom ash, cement and air foam. The engineering properties of the CGM are characterized as a function of the content of the various admixtures and the curing time in a laboratory test program. Several series of unconfined compression tests were carried out to characterize the strength and elastic properties of the CGM. Experimental results indicate that the unconfined compressive strength and modulus of CGM are influenced by the content of each component in the mixture. The unconfined compressive strength of CGM increases with an increase in curing time due to the pozzolanic reaction of the bottom ash. The strength after 28 days of curing is found to be approximately 1.5-2.3 times the strength after 7 days of curing, regardless of mix conditions. The bottom ash materials contain nearly 50% siliceous material and 13.9% CaO. With the removal of particles larger than 4.75 mm, a larger surface area is available to react with cement. It is postulated that the increase in shear strength is caused not only by the development of friction at the interface of the mixture components, but also by bond strength is due to the pozzolanic reaction of the bottom ash. Further study is needed, however, to discern aspects related to increase in pozzolanic reaction of bottom ash with the removal of larger size particles. The secant modulus of CGM is in the range of 185-480 times the unconfined compressive strength. The observed general trend is that the stiffness of CGM is greater than that of lightweight soil not containing the bottom ash as a component.