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- Updated January 19, 2001
REED on Largest Shotcrete Project in Southern California
The $2.4 billion Los Angeles "Alameda Corridor" project is a 10-mile-long,
50 foot wide by 33-foot-deep ditch which will take rail traffic below grade through
several industrial and residential neighborhoods. The Concrete Contractor on the project,
Condon-Johnson & Associates, Inc. of Los Angeles, pumped 25,000 cast-in-drilled holes
(CIDHs) to act as support for the walls of the depressed railway channel.
Superior Gunite of Lakeview Terrace, CA, was then called in to finish building the walls using the "shotcrete" method of concrete application.
It will still take them an estimated 2 years to complete their portion of the project. According to Mario Velasco,
who has been on the job since July, ".this is the biggest shotcrete project in Southern California right now."
Superior Gunite has 4 separate shotcrete crews running simultaneously for this large job. Each of the 8-man crews is
working on a special 86 foot long wheel mounted scaffolding unit that can be pulled by a Bobcat. Each crew works on
either the top half or bottom half of 3 "panels" (unfinished areas) each day. They then finish up those 3 unfinished panels
the following day, and so on. The mobile scaffolding method of shotcrete wall construction is the most efficient way to construct the walls.
Shotcreting large volumes of harsh, low slump mix over long distances
translates to exceedingly high pressure. Superior has been emptying
9 1/2
yard trucks of 2 inch minus slump concrete
in as little as 20 minutes, pushing through 200 feet of 2
inch hose. According to pump operator
Carlos Estrada "It's pretty harsh stuff, always less than a 2 inch slump".
Superior Gunite purchased a REED C50HPS
with 1867 psi maximum concrete pressure for this
demanding shotcrete application.
The sub-wall is not perfectly straight. Mario Velasco of Superior Gunite stated that ".since the support pilings aren't perfectly straight
and the outside of the wall needs to be straight, that wall has got anywhere from 14 inches
to 2 feet of solid shotcrete in it." The thick walls use quite a bit of concrete.
Each 84 foot long panel they cover uses 130 yards of concrete per side. After
the walls are finished, the entire bottom of the channel will be filled with 1 ½ "
rock. The rails then will go on top of the rocks.
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Questions? Send to mike.newcomb@reedmfg.com. |
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