Flowable fill is commonly used as an economical fill or backfill in road construction. It is usually a mixture of coal fly ash, water, a coarse aggregate (such as sand) and portland cement. Flowable fill can take the place of concrete, compacted soils or sand commonly used to fill around pipes or void areas. Other applications include filling in bridge abutments, foundation subbases or abandoned man holes and wells. Flowable fill can help put significant quantities of coal fly ash and spent foundry sand, two types of recovered materials, back to good use.