Filler material

The desired range of compressive strength in flow able fill mixtures depends largely on whether or not the hardened material may have to be excavated and removed at some future time. If removability is necessary, the ultimate strength of flowable fill should not exceed 1,035 kPa (150 lb/in2) or jack hammers may be required for removal.(1) For flowable fill mixes used for higher bearing capacity applications, such as structural fill or temporary support of traffic loads, a greater range of compressive strength mixtures can be designed. Flowable fill is considered a controlled low strength material by ACI as long as its compressive strength is less than 8270 kPa (1,200 lb/in2).