Recent Experience with Tremie Concrete Properties and Testing-Paper

Paper

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The paper examines the behaviour and testing of modern tremie concrete used in deep foundations, focusing on static segregation and recent industry guidance. Although admixtures and additions such as GGBS enable concrete to meet demanding workability requirements, they can also create mixes vulnerable to defects if stability is inadequate.<br /><br />Two London projects experienced static segregation: aggregate settled, leaving grout and mortar above sound concrete. In one case, low paste yield stress and viscosity, combined with delayed setting, allowed aggregate to sink. These incidents raised concerns about pile strength and durability, despite concrete meeting its specified mix requirements.<br /><br />The EFFC/DFI Best Practice Guide (2016) and the ICE specification (2017) recommend testing beyond traditional acceptance checks. Tests assess workability, flow retention, passing ability, bleeding, filtration and segregation. At an East London project, regular testing generally showed acceptable stability and concrete performance. Results also revealed that some tests—particularly the L-Box—could identify changes in mix behaviour that flow-table results did not. Field observations and pile-integrity testing supported the test findings.<br /><br />The authors conclude that detailed testing at mix-design stage and throughout construction helps verify concrete suitability, detect changes in supply and reduce construction risks. Full-scale trials can further assess concrete and construction methods under realistic conditions. However, current acceptance limits are based on limited data and may not suit all concrete types. Further research and case histories are needed to refine the limits and better understand how interface layers contribute to pile defects. Good workmanship and appropriate design remain essential alongside concrete testing.

Keywords

tremie concrete

deep foundations

static segregation

GGBS

admixtures

workability testing

pile defects

EFFC/DFI Best Practice Guide

L-Box test

pile integrity testing