Engineering students premier an ice arch made of pykrete

Alan Fearns/Sun Star Reporter
February 26, 2013

Encased in wood, the Ice Arch of UAF rises up from the ashes as it is constructed in the Cornerstone Plaza on February 20, 2013. Adam Taylor/Sun Star

Encased in wood, the Ice Arch of UAF rises up from the ashes as it is constructed in the Cornerstone Plaza on February 20, 2013. Adam Taylor/Sun Star

Civil Engineering students raised the annual ice arch in the Cornerstone Plaza last Wednesday at 12:30 p.m.  The ice arch is continuing the 50 year UAF tradition as a part of Engineering Week.

This year’s ice arch took on a boxed-in design and new color from the use of pykrete.  Pykrete is a composite material made up of sawdust and water.  Ryan Cudo, the arch designer and build team co-captain chose the material for its increased durability and slow melting rate.

“It’s the first time this has been done, I’m interested to see how it holds up,” said Tripp Collier, the treasurer of the UAF Chapter of the American Society of Civil Engineers.

Local Fairbanks company Ghemm Co., volunteered to operate the lift that placed the arch up, while four team members, two on each side of the arch, held and led it into place.  The team reviewed how the arch lined up according to their measurements.

One end of the arch was over-sanded, causing an imbalance when placed onto the supports.  Engineering students used their hard helmets to scoop snow, and packed in the gap with bare hands or pieces of plywood to keep the assembly moving.

“We’re real limited on what were allowed to use, since the campus pulls on safety.  It’d be real easy to get a chainsaw and flat drop it right on there,” Collier said.

Students foresaw the next concern. According to their observations, the columns or abutments, would not be tall enough to hold the top piece above the arch.

ASCE President Andy Chamberlain brought out a grinding tool and shoveled out a wall outlet to prepare for its possible use.  The grinder contains a custom wheel, designed by Wilhelm Muench, for shaving down ice. Muench is a Structural Engineering Teaching Assistant and master’s student that assists with the ice arch and steel bridge projects. “He’s probably one of the best resources all civil students have,” Collier said.

Around 1:30 p.m., abutments were placed beside the arch, while students sprayed water between the arch and it’s base.  After reinforcing the current structure with a pykrete solution, they decided to put on the top piece without grinding the arch’s tip beforehand.

ASCE vice president Pat Brandon and Team Captain Will Riley, stood on ladders at each side, and carefully lowered the final piece onto the abutments.  As expected, the tip of the arch was preventing the piece from laying flat.  Instead of using the grinder, Cudo passed them plywood to raise the abutments and the top piece was placed.  More pykrete was filled between the gaps containing plywood and the 2013 ice arch was complete.

Cudo began working on the new ice arch design last summer, starting with a solid ice design that uses rebar as the structural skeleton.  After speaking with various faculty and upperclassmen, Cudo learned the process needed so the arch would stand.  Then, Brandon brought up the idea of using pykrete for the arch.

“I wasn’t familiar with that material, and so questioning him, I learned what that was.  I thought it would be really cool to design something out of pykrete, something that had never been done before,” Cudo said.

Cudo brought the idea to Riley, who knew about pykrete already.  They worked on the initial design ratio, starting with the standard formula of 14 percent sawdust to 86 percent water by weight.  Flexural testing was done to test the tension of the pykrete.

The pykrete was saturated overnight, there was a more uniform distribution across the beams.  It froze six inches at a time, with no cracking temperatures at temperatures around 10 degrees. However, anything below zero, would cause large thermal cracks along the top.

Two by four framed forms were built in the steel bridge room, and would be used to mold the arch.  The abutments and top piece were constructed as one single piece and the arch was built out of several angled wooden squares.

“We were thinking it wouldn’t turn out too archy,” Riley said. “But as you can see, it’s pretty archy.”

During winter Break, the forms were broken apart and taken outside to be patched back together.  Riley, Cudo and Geological Engineering student Justin Calkins filled the forms with pykrete, one inch at a time to prevent cracking.

“As long facilities services doesn’t come and knock it down, it will theoretically last until June or July,” Cudo said.

Cudo and Riley are very satisfied with the results of this year’s arch.

“I had always heard about pykrete when I was young,” Riley said. “And now I’ve actually built something out of it.”

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