SonFill products are self leveling, self compacting and have a controlled strength gain. Our design mix can be custom made from combinations that may include Class C fly ash, Class F fly ash, Portland Cement and a proportional blend of water. SonFill flowable backfill products utilize the cementitious and pozzolanic properties of Class C fly ash to fill void areas that may be inaccessible to other types of backfill. SonFill products are a superior alternative to compacted backfill which requires more time and labor to install.