July/August 2023 - 105

Injection Grout Project
Summary
Prior to being able to install the steel
casing pipe, portions of an existing
stone/concrete embankment down the
side of the rails had to be eliminated. To
secure the structural integrity of the rail
during installation, steel sheeting and
which allowed the material to permeate
deeper into the soils prior to curing.
Injecting acrylamide grout into the soils
turned the noncohesive, silty soils into
almost the same consistency of clay,
which allowed for hand mining to
continue with ease. In total, approximately
35 gal (132 L) of acrylamide grout
Acrylamide grout has no suspended solids, higher
strength compared to acylates and greater longevity
compared to silicates.
soldier piles were driven into the earth
at the rail's edge on both embankments.
Holes were then burned into the sheet
piling and steel injection pipes were
driven through the holes into the loose
soil and injection pipes were installed.
Due to very warm site temperatures in
the 90°F (32°C) range on the day of
injection, the addition of potassium
ferricyanide (KFe) was introduced to the
grout mix. KFe is a chemical compound
used in small quantities to extend gel
times. It reacts as a reducing agent to
prevent free radical generation in the
solution, thereby retarding/slowing
vinyl polymerization of the chemically
activated gel systems from minutes to
10 or more hours.
was used to stabilize the soils ahead of
the steel casing.
Conclusion
The team completed research on
potential products to use for this
project. After a meeting and demonstration,
it decided to submit acrylamide
grout with Potassium KFe. By
utilizing acrylamide grout to stabilize
the soils, the steel casing was successfully
jacked through the stabilized
sandy soils allowing the 73.5 in (1.8 m)
outside diameter steel casing pipes -
and ultimately the grouted in place
67 in (1.7 m) outside diameter HDPE
corrugated pipes - to advance without
causing issues to supporting soils
To secure the structural integrity of the rail during
installation, steel sheeting and soldier piles were driven
into the earth at the rail's edge on both embankments.
Generally, an acrylamide grout
mixture at 10% concentration will yield
a set time of approximately 20-30
seconds at 72°F (22°C); for every 10° rise
in temperature, set time is cut in half. As
site temperatures were extremely
warm, the grout set time was faster than
required for project specifications.
Adding KFe allowed for a slower cure
time of approximately two minutes,
under the Amtrak rails. Crews continued
to work around the clock to
complete every phase of the project. By
the end of summer 2020, the project
was completed successfully with no
interruption to the surrounding Amtrak
rails or community. One of the most
difficult challenges of the Harbor Brook
Project was the fact that the twin pipes
only had 5 ft (1.5 m) of cover, which is
very shallow for a trenchless installation
with very limited subsurface
information and soil borings.
The general contractor had contacted
several geotechnical contractors
to develop a plan to stabilize the soils
under the rail, but none of the plans
presented seemed logical for this
project or affordable. Injection grouting
using acrylamide grout was the proper
product to ensure a successful project.
Adding KFe allowed for a
slower cure time of approximately
two minutes, which
allowed the material to
permeate deeper into the
soils prior to curing.
Cured acrylamide grout and silty soils ahead of
hand mining
Chris Hamilton, former Northeast regional
manager of Avanti, has more than 15 years of
industrial and geotechnical sales and
technical expertise. He has a bachelor's
degree in science marketing from Saint
Francis University and a master's in business
administration from University of
Phoenix. He is currently vice president of
sales and marketing at DLVEWS.
Jessica Williams is marketing manager
at Avanti International. She graduated with
a Bachelor of Business Administration,
Marketing from Texas State University.
DEEP FOUNDATIONS * JULY/AUG 2023 * 105
July/August 2023

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