Effects of Sand Characteristics and Fly Ash Contents on Properties of Flowable Fill

This research examines the effects of sand characteristics and fly ash contents on fresh properties and on the unconfined compressive strength of flowable fill mixtures. Additionally, this research investigates the flowability of wet and dry sands and the influence of fly ash addition on this property using a number of sand sources and various levels of fly ash addition. It was found that adding fly ash into dry or wet sand substantially influenced its flowability. In addition, it was found that the flowability of sand-fly ash mixtures was influenced by such sand properties as fineness modulus and uncompacted air void content. Similarly, other flowable fill properties, such as bleeding, subsidence, penetration resistance, and unconfined compressive strength, were observed to vary with the sand property and the amount of fly ash added into the mixture.