Reuse of waste foundry sand in structural flowable fill: engineering performance investigation

Abstract

Many laboratory investigations and case studies have validated performance of waste foundry sand (WFS) in excavatable flowable fill. As an alternative, structural flowable fill integrating WFS is becoming a growing market in the beneficial reuse program of WFS. Through experimental work, a pilot study was launched to probe mixture designs and engineering behaviors of structural flowable fills incorporating WFS from multiple foundry facilities with diverse casting backgrounds. WFS samples from 17 independent casting facilities were retrieved as investigation objects and blended individually with cement, fly ash and water in proportions to produce WFS structural flowable fills. Work scope includes tests of parameters: physical characteristics and chemical oxides of WFS, unconfined compressive strength, bleeding/shrinkage, and setting time/ penetration resistance of flowable fills. Results indicate that WFS samples vary in physical and chemical characteristics due to variation in casting operations and mineral nature, and the variation in physical and chemical characteristics is correlated with the variation of engineering behaviors of flowable fills. WFS structural flowable fills are able to demonstrate qualified performance. WFS are accordingly approved as a substantial reusable resource for structural flowable fills.