3
well as large open void spaces in need of remediation, near
mine level.
Over a two-month period, approximately 4,146 tons
of Liquid-Sand was injected into 20 boring sites. In order
to fill 5,300 cubic yards of estimated void space, 5,163
cubic yards of foamed sand slurry was injected. An average
of 276.6 cubic yards of foamed slurry was used per bore-
hole. As much as 260 cubic yards of foamed sand backfill
was gravity-injected in one day. In addition, as much as 260
cubic yards was installed by pumping a distance of up to
50 feet through the three-inch-diameter delivery line, into
the boreholes which were cased with three-inch-internal-
diameter, internally flush drill pipe. As much as 976 cubic
yards of foamed backfill was injected into a single borehole,
over several work shifts. The best performance was achieved
when the foam content was between 25% and 30% by
volume.
Economic savings were also tested on this project.
With the use of Liquid-Sand backfill, 0.85 acres of void
space was filled at an approximate cost of $525,000. This
same acreage would have cost between $1 million and $1.5
million to fill using traditional void fill grouting methods
with sand-cement-fly-ash grout.
SUMMARY AND CONCLUSION
Historically, underground void backfill applications have
been challenging and often costly with the use of tradi-
tional fill materials. The advance of Liquid-Sand technology
provides a cost-effective and environmentally safe alterna-
tive to traditional backfill methods. While underground
voids will always present a geotechnical challenge, with the
use of foam transportation technology these applications
can be completed with reduced labor, minimal materials,
and greater environmental security.
ACKNOWLEDGMENTS
This paper relies on research completed and data gath-
ered by a number of industry professionals who must be
acknowledged. These individuals include Milton Gomez,
Vice President of Aerix Industries and Chair of ACI 523
Joe Feiler, Senior Technical Engineer at Aerix Industries
Brian Masloff, Senior Research Scientist at Aerix Industries
and Sami Safi, Operations and Technical Support Engineer
at Aerix Industries.
REFERENCES
Aerix Industries. (2013). “ARX Transport: Foam Transport
for Solid Materials.” Aerix Industries, Golden, CO.
Aerix Industries. (2017). “An Introduction to Cellular
Concrete and Advanced Engineered Foam Technology
for Mine Backfills.” NAAMLP, September 2017.
Hallman, David. (2017). “Foamed Backfill for Subsidence
Mitigation.” Annual Conference of the National
Association of Abandoned Mine Land Programs,
Lexington, KY, September 2017.
well as large open void spaces in need of remediation, near
mine level.
Over a two-month period, approximately 4,146 tons
of Liquid-Sand was injected into 20 boring sites. In order
to fill 5,300 cubic yards of estimated void space, 5,163
cubic yards of foamed sand slurry was injected. An average
of 276.6 cubic yards of foamed slurry was used per bore-
hole. As much as 260 cubic yards of foamed sand backfill
was gravity-injected in one day. In addition, as much as 260
cubic yards was installed by pumping a distance of up to
50 feet through the three-inch-diameter delivery line, into
the boreholes which were cased with three-inch-internal-
diameter, internally flush drill pipe. As much as 976 cubic
yards of foamed backfill was injected into a single borehole,
over several work shifts. The best performance was achieved
when the foam content was between 25% and 30% by
volume.
Economic savings were also tested on this project.
With the use of Liquid-Sand backfill, 0.85 acres of void
space was filled at an approximate cost of $525,000. This
same acreage would have cost between $1 million and $1.5
million to fill using traditional void fill grouting methods
with sand-cement-fly-ash grout.
SUMMARY AND CONCLUSION
Historically, underground void backfill applications have
been challenging and often costly with the use of tradi-
tional fill materials. The advance of Liquid-Sand technology
provides a cost-effective and environmentally safe alterna-
tive to traditional backfill methods. While underground
voids will always present a geotechnical challenge, with the
use of foam transportation technology these applications
can be completed with reduced labor, minimal materials,
and greater environmental security.
ACKNOWLEDGMENTS
This paper relies on research completed and data gath-
ered by a number of industry professionals who must be
acknowledged. These individuals include Milton Gomez,
Vice President of Aerix Industries and Chair of ACI 523
Joe Feiler, Senior Technical Engineer at Aerix Industries
Brian Masloff, Senior Research Scientist at Aerix Industries
and Sami Safi, Operations and Technical Support Engineer
at Aerix Industries.
REFERENCES
Aerix Industries. (2013). “ARX Transport: Foam Transport
for Solid Materials.” Aerix Industries, Golden, CO.
Aerix Industries. (2017). “An Introduction to Cellular
Concrete and Advanced Engineered Foam Technology
for Mine Backfills.” NAAMLP, September 2017.
Hallman, David. (2017). “Foamed Backfill for Subsidence
Mitigation.” Annual Conference of the National
Association of Abandoned Mine Land Programs,
Lexington, KY, September 2017.