COMPARISON OF THE PRE-CONSTRUCTION AND PRODUCTION QC TEST RESULTS FOR THE SELA-22 ELLIPTICAL JET GROUTING PROJECT (NEW ORLEANS, LA)-Paper

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The SELA-22 project in New Orleans used elliptical bi-fluid jet grouting to create a soil-cement bottom plug beneath a drainage canal. The treatment had to provide full coverage between sheet-pile walls and meet 28-day requirements of at least 100 psi unconfined compressive strength (UCS) and hydraulic conductivity no greater than 1×10⁻⁶ cm/s.<br /><br />The contractor first conducted bench-scale tests on representative clay, transition, and sand soils using two binders and several grout proportions. The Portland-blast-furnace-slag blend (PBFC) was selected because it showed stronger overall performance and adequate permeability results. A full-scale field test then assessed material performance, column geometry, overlap, and construction parameters before production.<br /><br />Production quality-control results generally met the specifications. Across the project, average UCS was 355 psi and average hydraulic conductivity was 5.04×10⁻⁷ cm/s. Three UCS results (0.37%) and 22 permeability results (2.72%) did not meet the respective criteria.<br /><br />Comparisons across testing stages indicate that bench-scale UCS results could generally predict field strength without correction, although applying a correction factor to cohesive-soil results was useful in some cases. Bench-scale permeability results, by contrast, were typically about an order of magnitude higher than field and production results. The authors conclude that laboratory testing is valuable for selecting materials and mix proportions, but cannot reliably represent jet-grouting performance on its own. A well-designed field test is essential to verify geometry and tune construction parameters, while production QC/QA provides the final check on performance.

Keywords

elliptical bi-fluid jet grouting

SELA-22 project

New Orleans

soil-cement bottom plug

drainage canal

unconfined compressive strength

hydraulic conductivity

Portland-blast-furnace-slag blend

bench-scale testing

production quality control