Title:
SI Construction: The Impacts of Support Fluid on Drilled Shaft Construction (Prepublished)
Author(s):
Sarah Mobley, Kelly Costello, Tristen Mee, Kurt Kupselaitis, Cesar Quesada Garcia, Miles
Publication:
Structural Journal
Volume:
Issue:
Appears on pages(s):
Keywords:
construction; corrosion; deep foundations; drilled shafts; durability; reinforcing bar bond; side shear; slurry; support fluid
DOI:
10.14359/51751784
Date:
6/4/2026
Abstract:
Drilling support fluid is used to stabilize deep excavations during the construction of cast-in-place concrete foundations like drilled shafts. During concreting operations, flowable concrete, tremie-placed or pumped to the bottom of the excavation, displaces the lower-density support fluid. Reinforcement cage congestion from tight rebar spacing requires concrete to build sufficient pressure head inside the reinforcement cage before radially filling the annular cover region. Even under ideal conditions, the support fluid-concrete interface produced during radial flow has been proven to impact side shear capacity, corrosion resistance, concrete strength, and rebar bond strength. These effects largely go unnoticed. This paper compiles the findings of 13 studies conducted to highlight the impact of support fluid performance on drilled shaft construction while providing recommendations vital to the evolution of concrete placement practices in deep excavations.