The Deep Foundations Institute (DFI) and European Federation of Foundation Contractors (EFFC) have released a free download of their recent Best Practice Guide to Tremie Concrete for Deep Foundations.
The task group recognized the potential for improving project quality and cost effectiveness by remedying tremie concrete practice, members identifying significant issues related to the use of mixes with insufficient workability, stability or robustness; poor specifications; and, inadequate testing procedures.
Guide to Tremie Concrete authors also cite a) trends favoring higher strength concrete classes and lower water/cement ratio mixes, each hinging on admixtures to compensate for reduced workability and address often competing demands for workability in the fresh state and setting time; b) how current testing methods have not evolved at comparable pace to allow results to reflect more complex mixes' rheological properties; and, c) tendencies to base acceptance on slump or flow table test results.
Methods for accomplishing this task include tremie concrete
, replaced aggregate concrete, using a bottom-opening bucket, pumped concrete, or bagged concrete.
Each pile forming the barrier wall was cast in three steps over an 11-to 12-day cycle: I) slurry wall excavation down to top of bedrock, with tremie concrete
backfill; 2) directional drilling of pilot hole behind initial concrete layer; and, 3) pilot hole-guided drilling of cylindrical pile into the bedrock, tremie concrete
backfill for full-depth, finished wall.