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Precast Concrete Tunnel Liner Segments
This technically complex project called for the manufacturing of
wet-cast reinforced concrete tunnel liner segments and an advanced
curing regimen.
The custom solution from Kraft Energy™ allowed the
large tunnel segments to be vapor cured in stages.
After production of the segments in steel moulds,
the filled moulds moved along rails through a tunnel at 115°F
(46°C) for eight hours of initial curing. After the segments
left the tunnel, they were demoulded and transported to one of
10
curing tents where they underwent the following curing regimen:
- Nine hours at 115°F (46°C)
- 19 hours at 110°F (43°C)
- A cool-down over a period of 6 days at 86°F (30°C)
Each of the 10 tents featured concrete masonry
side walls and the roof, rear door and front door were made of nylon-reinforced
vinyl. A vapor distribution system located behind the tents provided
heat and humidity. Each tent was individually temperature controlled
via automatic vapor control valves and temperature sensors. A circulation
fan, located inside each tent, stabilized temperatures and reduced
condensation.
A key challenge was designing a system that allowed
the concrete tunnel liners to arrive at the tents at staggered
times
over a six-hour period while maintaining curing temperatures in
the tent. Kraft Energy’s solution was to design a
tent system that featured curtains and a start-stop panel that
prevented vapor
from escaping.
The tunnel, maintained at 115°F (46°C), and the tents,
maintained at various temperatures for seven days, used the following
equipment from Kraft Energy: 
- One Vapor Generator 25VS™
- AutoCure™ curing control system
- Siemens Simateic® S7 central processor
- Touch Screen Graphic User Interface
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