Flowable fill refers to a cementitious mixture containing cementitious materials , fine aggregate, water and sometimes fillers or admixtures. Flowable fill is especially useful in backfill applications where irregular voids or difficult to reach spaces make conventional backfill difficult.  Flowable fill mixtures can range in flowability but are generally placed as self leveling, hardening in a matter of hours without the need for compaction in layers. Flowable fill is also known as controlled density fill (CDF), controlled low strength material (CLSM) and non shrink fill.