Title:
Determining When Drilled Shafts are Mass Concrete (Prepublished)
Author(s):
Amanda Lewis, Kevin Johnson, Abla Zayed, and Gray Mullins
Publication:
Materials Journal
Volume:
Issue:
Appears on pages(s):
Keywords:
drilled shaft; mass concrete; thermal integrity profiling; thermal modeling
DOI:
10.14359/51749125
Date:
8/19/2025
Abstract:
The term “mass concrete” characterizes a specific concrete condition that typically requires unique considerations to mitigate extreme temperature effects on a structure. Mass concrete has historically been defined by the physical dimensions of a massive concrete element with the intent of identifying when differential temperatures may induce early-onset cracking, leading to reduced service life. More recently, in addition to differential temperature considerations, extreme upper temperature limits have been imposed by the American Concrete Institute to prevent long-term concrete degradation. Studies dating back to 2007 show shafts as small as 48 in. (1.2 m) in diameter can exceed both differential and peak temperature limits; in 2020, augered cast-in-place piles as small as 30 in. (0.76 m) in diameter exceeded one or both limits. This suggests the term “mass concrete” is misleading when considering today’s high-early-strength or high-performance mix designs. This study applies numerical modeling coupled with field measurements to investigate the effects of concrete mix design, drilled shaft diameter, and environmental conditions on heat energy production and temperature. Further, the outcome of this study focuses on developing criteria that combine the effects of both size and cementitious material content to determine whether unsafe temperature conditions may arise for a given drilled shaft design.