I was touring a site with Tony, the project manager. An expert in the
field, Tony was my go-to guy to help me understand the intricacies of construction.
Walking into a large warehouse under construction, we came upon a crew struggling to lay
down a zillion yards of concrete.
Figure 2: Pouring Concrete on Conventional Steel Reinforcing "Rebar"
(Photo by TJ Lyons)
As we walked, we had to watch where we placed our feet very closely,
every step, for few things are as tricky as the
balancing act you must do while walking across rebar. I counted 20 workers trying to
navigate this mess. I went over and asked the concrete superintendent how many people
were working.
This was a 24-hour pour. He had 20 workers scheduled for each of the 3
shifts. How heavy was the hose when full of concrete? He was unsure. I checked, and it's
about 400 pounds per section. So, the 8 sections weighed 3,200 pounds—a ton and a half.
How many workers had to maneuver the hose? Eight, he said. That's 400 pounds per worker.
No need to lift it, though, just drag the weight, he informed me. I then asked the
project manager and concrete superintendent if they
had worked with fiber-reinforced concrete (FRC)? Both asked, "What's that?"
The following part of this article focuses on the need for the
construction industry to embrace two fairly recent innovations: using FRC where
conventional rebar is replaced by adding tiny steel or other fibers like polyester to the concrete when it's poured and placing the
concrete using a remotely controlled robot-like machine, not workers.
I call the technique "Sikaflow," based on working with two of the
leaders in that area, Sika, which produces the microfibers in an "admixture," and
Somera, a firm that makes one of the "robot" machines called the "line-dragon." There
are other firms that supply these, but I have worked closely with these two.
I met with both firms and suggested the idea of putting these two
technologies together. Using admixture in concrete to replace rebar has been around for
awhile as well as the use of the line-dragon to place it has been in use for about a
decade. I saw the first line-dragon in use at a Jacobs pharmaceutical project in
Virginia in 2018. It's a game changer.
Reduced Production Costs
This technology is cheaper, much cheaper—about 20 percent cheaper
than using workers to pour concrete over rebar. The table below shows where the
savings occur on flat work without the use of rebar. As mentioned earlier, placing
and tying conventional rebar for flat work is replaced with microfibers that are
included in the mix. It's too simple! You can do so much work, so much faster, using
fewer workers. The task is easier on those doing the work and safer. More on that
later.
Traditional Reinforcing Rebar
Use of FRC
Sorting of loads, reloading, and
delivery-to-task area
Eliminated
Cutting rebar to lengths needed
Eliminated
Bending rebar to shape
Eliminated
Placing of bolsters or chairs for
rebar
Eliminated
Unloading of rebar at the task
site
Eliminated
Hand carrying of rebar to the placement
site
Eliminated
Arranging and hand-tying of the
rebar
Eliminated
To get a feel for where the savings come from, I asked Sika to run
the numbers for a project. It's cheaper, for sure.
Safety Concerns
Quoting Walt Kelly's Pogo comic
strip, "We have met the enemy and he is us," rings so true. The use of reinforcing
steel, like rebar, has been going on for over a century. Taking long bits of heavy
steel and wiring them together by hand and with pliers is steeped in tradition. The
rebar "rodbuster" is regarded for the brutal work they do every day and the strength
that comes with it.
Figure 3: Bringing Material to Task: Note the Roll of Wire on
the Belt for the Tying of Rebar (Photo by TJ Lyons)
When a worker was asked about how hard it was to bend down and
tie each piece, he answered, "You have to embrace the suck…." The workers just
take the beating.
As the show ends, the superintendent brings out a tool to try
out. The super proudly announced, "This is new technology," and showed Mike a
battery-powered tool that did the knot by just pulling a trigger. "That's what
we use with our new guys." Mike then asked the obvious question, "But why
doesn't everybody up here have one?" The super answered,"We use them sparingly,
for ultimately you have to learn how to tie."
But there is a cost to throwing young bodies into work that is
harder based on our traditions. The constant bending to pick up lengths of rebar and
then place and tie them is brutal. When a worker puts in a claim at age 35 after a
decade of damage, general contractors wring their hands in anguish, confused about
how the injury could have occurred. They may have a solid safety program, but they
are wearing out their workers. How prevalent are injuries?
Reinforcing ironworkers have reported high prevalence rates
for work related musculoskeletal disorders (WMSD) symptoms affecting the
low–back (80.2%) and wrists/hands (48.4%) [Cook et al. 1996]. Boston-area
rodbusters reported high prevalence rates for self-reported symptoms of the
low-back (52.2%) and hands/wrists/fingers (47.8%) and high prevalence rates of
doctor-diagnosed WMSDs, including ruptured spinal discs (14%) and carpal tunnel
syndrome (16%) [Forde et al. 2005].
Source: "Reducing Work-Related
Musculoskeletal Disorders Among Rodbusters," National Institute of Health,
National Institute for Occupational Safety and Health, Workplace Solutions,
November 2009.
The US National Institute of Health (NIH) investigated how bad
this work is, comparing it to other work where bending is needed, such as
painting.
The long term effect of heavy construction work on the back
the occurrence of postures, lifting, carrying, and accidents in concrete
reinforcement work and in maintenance house painting were measured. The 32,620
observations covering 272 work hours showed that reinforcement work necessitated
stooped postures and heavy lifting more often than did painting. Reported minor
back accidents were more than ten times as common in reinforcement work than in
painting (1.3 compared with 0.11 accidents per man-year, p less than 0.001).
With the recent need to work toward sustainability, resource
recovery, and carbon footprints, this is a perfect fit for that effort. Consider the
site reduction in handling and the savings in steel when conventional reinforcing
steel is eliminated for flat concrete work.
Figure 4: Typical Rebar Assembly for Flat Work (Photo by TJ
Lyons)
A unique advantage of the Sikaflow method is its efficiency and
reduction in harm to workers doing the work and to our environment. The introduction
to the US Green Building Council credit states the intent is "to support
high-performance cost-effective employee safety and health outcomes across the
building life-cycle through early attention to
safety and health hazards." [Emphasis added.]
The Sikaflow method checks all of the boxes for a Leadership in
Energy and Environmental Design (LEED) credit. From the reduction in steel needed to
the elimination of tasks that require energy, like the continuous movement of rebar
when delivered to its placement.
The reduction of risk to workers has also been proven. The LEED
Prevention Through Design credit (IPpc93) will be awarded if applicants "perform
safety constructability reviews before the completion of schematic design to explore
and plan the how safety and efficiency can be optimized during construction."
By linking these two technologies, we can make the work easier for
workers while allowing those workers to accomplish more in a day. We can eliminate
needless injuries to workers by both handling rebar to get to the site and reducing
what I see as needless damage to good people tying rebar. There is no need for that
since both robots and tools have replaced that injurious task.
The construction industry needs to be relentless in embracing
technology, strengthening efficiency, and fostering injury prevention. Like the
production of ashtrays and typewriters, we must also abandon some traditions in our
workplace.
Opinions expressed in Expert Commentary articles are those of the author and are not necessarily held by the author's employer or IRMI. Expert Commentary articles and other IRMI Online content do not purport to provide legal, accounting, or other professional advice or opinion. If such advice is needed, consult with your attorney, accountant, or other qualified adviser.
I was touring a site with Tony, the project manager. An expert in the field, Tony was my go-to guy to help me understand the intricacies of construction. Walking into a large warehouse under construction, we came upon a crew struggling to lay down a zillion yards of concrete.
As we walked, we had to watch where we placed our feet very closely, every step, for few things are as tricky as the balancing act you must do while walking across rebar. I counted 20 workers trying to navigate this mess. I went over and asked the concrete superintendent how many people were working.
This was a 24-hour pour. He had 20 workers scheduled for each of the 3 shifts. How heavy was the hose when full of concrete? He was unsure. I checked, and it's about 400 pounds per section. So, the 8 sections weighed 3,200 pounds—a ton and a half. How many workers had to maneuver the hose? Eight, he said. That's 400 pounds per worker. No need to lift it, though, just drag the weight, he informed me. I then asked the project manager and concrete superintendent if they had worked with fiber-reinforced concrete (FRC)? Both asked, "What's that?"
The following part of this article focuses on the need for the construction industry to embrace two fairly recent innovations: using FRC where conventional rebar is replaced by adding tiny steel or other fibers like polyester to the concrete when it's poured and placing the concrete using a remotely controlled robot-like machine, not workers.
I call the technique "Sikaflow," based on working with two of the leaders in that area, Sika, which produces the microfibers in an "admixture," and Somera, a firm that makes one of the "robot" machines called the "line-dragon." There are other firms that supply these, but I have worked closely with these two.
I met with both firms and suggested the idea of putting these two technologies together. Using admixture in concrete to replace rebar has been around for awhile as well as the use of the line-dragon to place it has been in use for about a decade. I saw the first line-dragon in use at a Jacobs pharmaceutical project in Virginia in 2018. It's a game changer.
Reduced Production Costs
This technology is cheaper, much cheaper—about 20 percent cheaper than using workers to pour concrete over rebar. The table below shows where the savings occur on flat work without the use of rebar. As mentioned earlier, placing and tying conventional rebar for flat work is replaced with microfibers that are included in the mix. It's too simple! You can do so much work, so much faster, using fewer workers. The task is easier on those doing the work and safer. More on that later.
To get a feel for where the savings come from, I asked Sika to run the numbers for a project. It's cheaper, for sure.
Safety Concerns
Quoting Walt Kelly's Pogo comic strip, "We have met the enemy and he is us," rings so true. The use of reinforcing steel, like rebar, has been going on for over a century. Taking long bits of heavy steel and wiring them together by hand and with pliers is steeped in tradition. The rebar "rodbuster" is regarded for the brutal work they do every day and the strength that comes with it.
In a previous column from January 17, 2025, "Shortcuts and Tradition Can Hamper Safety," I referred to a conversation on the series Dirty Jobs with Mike Rowe. The segment was on rodbusters and the work they do.
But there is a cost to throwing young bodies into work that is harder based on our traditions. The constant bending to pick up lengths of rebar and then place and tie them is brutal. When a worker puts in a claim at age 35 after a decade of damage, general contractors wring their hands in anguish, confused about how the injury could have occurred. They may have a solid safety program, but they are wearing out their workers. How prevalent are injuries?
The US National Institute of Health (NIH) investigated how bad this work is, comparing it to other work where bending is needed, such as painting.
Other Advantages
With the recent need to work toward sustainability, resource recovery, and carbon footprints, this is a perfect fit for that effort. Consider the site reduction in handling and the savings in steel when conventional reinforcing steel is eliminated for flat concrete work.
A unique advantage of the Sikaflow method is its efficiency and reduction in harm to workers doing the work and to our environment. The introduction to the US Green Building Council credit states the intent is "to support high-performance cost-effective employee safety and health outcomes across the building life-cycle through early attention to safety and health hazards." [Emphasis added.]
The Sikaflow method checks all of the boxes for a Leadership in Energy and Environmental Design (LEED) credit. From the reduction in steel needed to the elimination of tasks that require energy, like the continuous movement of rebar when delivered to its placement.
The reduction of risk to workers has also been proven. The LEED Prevention Through Design credit (IPpc93) will be awarded if applicants "perform safety constructability reviews before the completion of schematic design to explore and plan the how safety and efficiency can be optimized during construction."
By linking these two technologies, we can make the work easier for workers while allowing those workers to accomplish more in a day. We can eliminate needless injuries to workers by both handling rebar to get to the site and reducing what I see as needless damage to good people tying rebar. There is no need for that since both robots and tools have replaced that injurious task.
The construction industry needs to be relentless in embracing technology, strengthening efficiency, and fostering injury prevention. Like the production of ashtrays and typewriters, we must also abandon some traditions in our workplace.
Opinions expressed in Expert Commentary articles are those of the author and are not necessarily held by the author's employer or IRMI. Expert Commentary articles and other IRMI Online content do not purport to provide legal, accounting, or other professional advice or opinion. If such advice is needed, consult with your attorney, accountant, or other qualified adviser.