Strength of Lime-Treated Fly Ash Using Bentonite

Abstract

Fly ash has many bulk applications; but Class ‘F’ fly ash being non-cohesive, has to be strengthened or reinforced when used in structural fills. Portland cement and lime are the usual additives for strengthening fly ash. The strength from such additions comes from pozzolanic reactions. In this study, bentonite was used to augment pozzolanic reactions of fly ash with lime, producing very high unconfined compressive strength exceeding 7000 kPa. The strength increased by 88% because of 20% addition of bentonite at the optimum lime content of 13% by weight. There was no adverse effect in terms of swell after adding bentonite. The addition of bentonite also increased the elastic modulus of fly ash-lime combine.