Research and Development Office

Evaluating Methods to Apply Cellular Concrete on Reclamation Operation and Maintenance Projects

Project ID: 2584
Principal Investigator: Norris Skinner
Research Topic: Repair and Maintenance
Funded Fiscal Years: 2016 and 2017
Keywords: None

Research Question

What are effective methods to pump concrete repair materials long distances for large scale
tunnel repairs?
A Value Engineering (VE) study was performed for the Cunningham Tunnel Repair project in
March 2015 to consider methods to repair a portion of a concrete tunnel that was over a mile
into the tunnel. Concrete has never been pumped that far. One concept proposed was to make
the concrete lighter by entraining air, and then remove the air at the placement. The Eastern
Colorado Area Office has provided the TSC's MERL approximately $30,000 to start considering
the applicability of this VE proposal.

Need and Benefit

A potential alternative discussed in the Cunningham VE study was the use of cellular concrete to
repair the scour damage along the invert of the tunnel. With traditional repair methods, bags of
concrete would need to hauled into the tunnel along with a mixer. Getting material into the site
is laborious, potentially unsafe and time consuming. The repair would likely take two
construction seasons to complete. The use of cellular concrete would eliminate the need to haul
materials into the tunnel and set up a mixing operation. Cellular concrete would be pumped into
the tunnel and placed in the sour damaged areas. If cellular concrete is viable, the repairs could
be completed in one construction season with an approximate savings of $380,000 as identified
in the VE study for this project.
Over time all infrastructure requires repair and maintenance. The development of cost effective
solutions to the ever increasing need for repair is the main focus of this research. In this case
the ability to provide easier transport of repair material to the needed locations would be a
significant improvement toward maintaining a sustainable, and safe waterway infrastructure.
Tunnel construction generally consists of three typical sections in our inventory. Sections are
fully concrete lined, shotcrete lined or unlined. Fully lined tunnel sections are installed due to
highly fractured rock, incompetent rock or rock with insufficient weatherability. Shotcrete lined
sections are sections that have limited fractures, have medium competency and medium
weatherability. Unlined sections typically have limited fracture, are competent and are resistant
to significant weather over time. Often in tunnels, the transition zone on the downstream end of
a fully lined section is not long enough to provide a smooth transition from the lined typical
section to the shotcrete typical section. This causes turbulent water to erode the shotcrete invert
and undercut the tunnel walls.

Contributing Partners

Contact the Principal Investigator for information about partners.

Research Products

Bureau of Reclamation Review

The following documents were reviewed by experts in fields relating to this project's study and findings. The results were determined to be achieved using valid means.

Pumping Cement-Based Materials (final, PDF, 1.8MB)
By Tim Lannen, N. Dave Skinner
Research Product completed on September 30, 2018

Strength and Abrasion Testing of Cellular Grout (final, PDF, 676KB)
By Tim Lannen, N. Dave Skinner, Jeffery (Scott) Keim
Research Product completed on September 30, 2018

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