EFFC/DFI Guide to Support Fluids for Deep Foundations, First Edition-PDF

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The 2019 EFFC/DFI Guide to Support Fluids for Deep Foundations provides practical guidance for selecting, preparing, using, testing and disposing of fluids used to stabilize excavations for piles, diaphragm walls and related foundations. It is intended to complement—not replace—project specifications, standards and codes, and does not recommend one fluid type for every site.<br /><br />Support fluids must maintain excavation stability, limit fluid loss, remain workable during construction, be displaced by concrete, manage excavated particles and avoid harming the finished foundation. Their performance depends on ground and groundwater conditions, excavation geometry and equipment, construction duration, water quality, environmental constraints and disposal requirements. The guide discusses mineral fluids such as bentonite, natural and modified polymers, synthetic polymers such as PHPA, blended systems, and cases where water alone may be suitable.<br /><br />The guide emphasizes considering fluid effects at the design stage, including excavation stability, shaft and base resistance, reinforcement bond and concrete quality. Site investigation, appropriate equipment and trained personnel are essential. Full-scale trials are recommended where project risks or unfamiliar conditions justify them.<br /><br />Fluid properties change throughout excavation and reuse. No single test adequately characterizes a fluid, so quality control should combine appropriate measurements—such as density, viscosity, sand content, filtration and pH—with sampling at relevant depths and stages. Testing frequency and acceptance criteria should reflect fluid type and project requirements. Clean fluid and an adequately cleaned excavation base are especially important before tremie concreting.<br /><br />The guide also addresses mixing and storage, pumping, solids separation and recycling, contamination, fluid losses, environmental protection, waste disposal and worker safety. It cautions that pumping can damage some synthetic polymers and that disposal requirements depend on local regulations and the composition of the used fluid and excavated material. Overall, it promotes informed, site-specific fluid selection and continuous monitoring to protect both construction performance and the integrity of the completed foundation.
Keywords
support fluids
deep foundations
bentonite
polymer fluids
excavation stability
diaphragm walls
pile foundations
fluid testing
tremie concreting
groundwater conditions