The EFFC/DFI Guide to Support Fluids for Deep FoundationsÂ-PPT Presentation

PPT Presentation

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The EFFC/DFI Guide to Support Fluids for Deep Foundations promotes good practice in managing fluids used to stabilize deep excavations. Support fluids help maintain trench stability, transport cuttings, cool and lubricate excavation tools, and must be displaced effectively by concrete or grout. Their properties are closely linked to concrete quality and construction outcomes, particularly for larger, deeper elements and densely reinforced designs. Effective management can also improve productivity and reduce treatment and disposal costs.<br /><br />The guide covers fluid design and management, raw materials—including bentonite, natural and synthetic polymers, and blends—field testing, execution, treatment, and relevant international standards. A second edition is planned for 2023–2024, following field and academic research.<br /><br />The field research study is collecting data from pile and diaphragm-wall sites using both standard and non-standard tests. It monitors fluid properties during excavation, base cleanliness, concrete levels and properties, and the interface layer. Research partners are investigating topics such as filter-cake formation, fluid loss, polymer chemistry, soil–concrete interface behavior, and defects in diaphragm walls.<br /><br />By the time of the presentation, about half of the scheduled site visits were complete. Findings included evidence of consistent fluid properties throughout the fluid column and useful comparisons of sampling and base-quality assessment devices. Further development is needed for automatic in-situ monitoring. Vibracores can help assess the interface layer and obtain small samples, while a three-part sampler can collect larger samples. The study aims to test the interface layer directly in trenches using vane-shear equipment and seeks additional site proposals to complete the program.

Keywords

deep foundations

support fluids

bentonite

polymer fluids

trench stability

diaphragm walls

field testing

concrete quality

fluid management

interface layer