November/December 2021 - 83

The temperature versus depth for suspended wires 7
hours after concrete placement and shaft cooling
coolest perimeter wire, which is above
the 35°F (19.4°C) limit. Anomalous zones
in the concrete are unlikely to be considered
with any regularity when making
temperature differential predictions.
Temperature versus depth measurements
were also evaluated at shaft
peak temperature, which was about 22
hours after concrete placement. The
concrete in the previously discussed
anomalous zones have hydrated and
increased in temperature to resemble
the surrounding concrete, with the
temperature differentials being within
the limits. Based on the drilled shaft
logs, each small truck raised the
concrete level by about 3.5 ft (1.1 m),
meaning each of the two temporarily
cooler zones were likely comprised of
cement from 3 to 4 trucks. Furthermore,
the CSL results did not indicate
potential zone anomalies, suggesting
the cooler zones were not the result of a
concrete quality issue, but of concrete
there taking longer to hydrate. Because
of the relatively continuous data
collection with the thermal wires, it
was clear to see that the temperature
differential limit was exceeded at 11
hours, but not at 22 hours.
Conclusion
Based on construction of large diameter
drilled shafts that were studied in South
Carolina, a cooling system was more
effective at cooling the interior of a shaft,
and the introduction and termination of
cooling water had an impact on the
maximum and differential temperatures.
Additionally, thermal wires at
both a shaft perimeter and its interior
were able to measure the cooling effect
of a flowing, tidal river, which greatly
impacted the measured temperatures
above the mudline.
The authors previously determined
that convection currents occur in
water-filled CSL tubes and make TIP
with suspended wires less effective at
identifying integrity issues (Proceedings
of IFCEE 2018, ASCE GSP 294). This
study suggests such limitations are not
as applicable when monitoring the
effectiveness of a mass-concrete
cooling system. However, it may still be
difficult to measure and limit the
maximum temperature differential
across a shaft due to site conditions,
environmental effects and concrete
variability.
Acknowledgments
This project was made possible by
SCDOT, including coordinating the
wo r k . GRL Eng i nee r s and PDI
generously provided engineering
support and equipment.
Greg Canivan, P.E., is a technical principal
with S&ME in its Charleston, South
Carolina, office. A practicing geotechnical
engineer for 25 years, he provides senior
leadership to S&ME's deep foundation
testing group. Canivan is on the board of
directors of the Pile Driving Contractors
Association (PDCA), is a past president of its
South Carolina chapter, and is active in DFI's
Driven Pile, Drilled Shaft, and Testing and
Evaluation committees.
David Schoen, P.E., is a project manager in
S&ME's Charleston, South Carolina, office.
Over the past 10 years, Schoen has become
proficient in the design and testing of deep
foundations, and is currently managing
S&ME's deep foundation testing group that
performs crosshole sonic logging, thermal
integrity profiling, low-strain integrity
testing and high-strain dynamic testing.
Temperature vs. depth for suspended wires 11 h after end of concrete placement (left), and 22 h after concrete
placement ended (right)
DEEP FOUNDATIONS * NOV/DEC 2021 * 83

November/December 2021

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