Flowable fill is a self-compacting low strength material with a flowable consistency that is used as an economical fill or backfill material as an alternative to compacted granular fill. Flowable fill is not concrete nor it is used to replace concrete. Terminology used by ACI Committee 229 is Controlled Low Strength Material (CLSM). Other terms used for this material are un-shrinkable fill, controlled density fill, flowable mortar or lean-mix backfill.
