Concrete On-Site March 2022

MARCH 2022

A WATER-BASED SOLUTION JET TECHNOLOGY FOR REPAIR AND SURFACE PREP IN THIS ISSUE: 35 World of Concrete Report | 36 Concrete Repair

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TRADE SHOW

WOC 2022

draws thousands to Vegas

Providing an opportunity for attendees to view new equipment and talk shop, the most recent edition of World of Concrete was the live, and productive, event that many in the industry needed it to be.

PHOTOS: ON-SITE AND INFORMA MARKETS

W

hile not quite as large as its pre-Covid editions, the 2022 World of Concrete, held January 18 to 20 in Las Vegas, Nev., featured consistent foot traffic and high engagement in the expo halls.

With almost 37,000 construction and masonry professionals registered, the general consensus was that the show stepped up to meet, and exceed most expectations, and underscored the industry’s need for in-person connections.

“The level of engagement from companies of all sizes and corners of the industry was very encouraging, especially following the past couple challenging years, and points to the revival of the trade show industry and continued growth of the construction and masonry sectors,” remarked Jackie James, group director of World of Concrete. “We are thrilled with the positive feedback we’ve received from our community, buyers and suppliers alike.”

Attendees were able to demo some of the industry’s latest, cutting-edge products, and to see the latest industry developments that lay the groundwork for the coming years, including 3-D printing with concrete, automated rebar tying machines, and remote operation of equipment.

World of Concrete is an annual international event dedicated to the commercial concrete and masonry construction industries. The event features indoor and outdoor exhibits from the industry’s leading suppliers showcasing innovative products and technologies, along with demonstrations, competitions and a world-class education program.

The next edition of the show is scheduled for January 17 to 19, 2023, again at the Las Vegas Convention Center in Nevada.

Aaron Kleingartner, product and dealer marketing manager at Doosan Infracore North America shows the company’s DX50Z mini excavator.

Crowds were thick on Day 1 of World of Concrete 2022.

COBOD 3D shows how 3D printing of concrete has the potential to be a game-changer for building construction.

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CONCRETE REPAIR

Using water to address common concrete errors.

BY KEITH ARMISHAW

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ouring concrete is a complex process. One slight miscalculation on any of the numerous variables can spoil a whole batch. Unfortunately, mistakes aren’t always evident right away, which can put timetables and budgets at risk.

Fortunately, advances in concrete removal methods are making them easier to fix, without demolishing everything and starting over.

For large, multi-phase construction projects, hydrodemolition, which some may refer to as hydro blasting, hydro-milling or water-jetting, offers a fast, cost-effective solution for concrete removal that can minimize the overall impact of errors. It’s even been known to get contractors back on track for on-time project delivery.

Not sure about where this option might come in handy? Here is a look at a few common concrete issues that water-based hydrodemolition can help solve.

PHOTO: COURTESY OF AQUAJET.

FINDING P A FIX

FORMWORK FAILURE

PHOTO: COURTESY OF AQUAJET.

Whether it’s a minor shift or a full-on blowout, formwork failures can spell disaster in terms of lost productivity. Correcting the problem often relies on handheld equipment and a lot of slow, backbreaking work that can take a considerable physical toll on crewmembers.

It can also take a toll on the rebar, as heavy vibrations and chipping tools can damage rebar and leave microfractures in the remaining concrete. When this happens, contractors are often left with no choice but to demolish most, if not all, of the structure.

Hydrodemolition is an impact-free concrete removal method that is considerably faster than jackhammers and other handheld options. Using high-pressure water jets as powerful as 40,000 psi, hydrodemolition demolition equipment blasts away layers of concrete, descaling the rebar in the process.

The use of water minimizes the risk of microfractures, creating a structurally sound foundation for any necessary concrete repairs. The use of high-tech, robotic systems can also minimize labour requirements, freeing up the rest of the crew to focus on other tasks like getting concrete forms back in place.

Hydrodemolition may also help when other equipment just can’t reach. I know of a small overpass project that experienced the shift of its formwork where water provided an ideal solution.

FOR OVER 80 YEARS MAX developed the World’s First battery powered rebar tying tool in 1993 and has a history of manufacturing durable and reliable industrial tools for 80 years. Since then, MAX rebar tying tools have revolutionized rebar tying work in a variety of jobsites all around the world.

All MAX products are engineered to perform on professional contractors jobsites and with MAX’s 200 R&D engineers we have continued to improve upon MAX proprietary technology, which led to the invention of the TWINTIER® rebar tying tools. TWINTIER® technology allows the tools to tie 5,000 ties per charge while delivering just the right amount of wire for greater productivity and cost savings. These unique innovative features make the TWINTIER® the most efficient rebar tiers in the industry. Today, MAX manufactures a full line of rebar tying tools that can tie between mesh up to #9 x #10 rebar.

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MAX USA Corp. • 205 Express St. • Plainview, NY 11803 • U.S.A. • Phone: (800) 223-4293 • FAX: (516) 741-3272 • www.maxusacorp.com on-sitemag.com / 37 OnSite_MaxUSA_March22.indd 1

2022-03-03 1:23 PM

PHOTO: COURTESY OF AQUAJET.

CONCRETE REPAIR

While part of the pour met specifications, the contractor needed to remove part of the deck and abutment to a depth of three feet (0.9 metres) and repour to correct the shift. Reaching the necessary depth with jackhammers wasn’t possible without destroying rebar and overall structural integrity, so he turned to hydrodemolition to remove the concrete to make a repair with minimal impact on the structure.

CONCRETE SEGREGATION Another contractor was able to use hydrodemolition’s selective removal capabilities to help solve a difficult concrete segregation problem. When water infiltrated his forms and washed out the cement paste, just the aggregate was left behind. The contractor was able to set parameters for

38 / MARCH 2022

the hydrodemolition robot to remove just the segregated material, leaving the sound concrete intact and ready for repair.

Hydrodemolition robots allow contractors to adjust the robot’s stroke to control the depth of cuts and vary the pressure of the water jet to match the task, whether that is removing loose, deteriorated concrete or lowering the sound concrete to a pre-determined depth. This enables pinpoint accuracy in concrete segregation and bleeding situations. Once the parameters are set, the robot meticulously maneuvers over the designated area, removing material according to set values.

OFF-SPEC EMBEDDED MATERIALS Sometimes the concrete error isn’t a result of the concrete mixture itself.

Sometimes materials like rebar or anchors

are placed in the wrong spot, or a design change necessitates their removal from set concrete.

In addition to setting parameters for stroke and pressure, cutting-edge hydrodemolition machines can be programmed to cut geometric shapes. This allows contractors to remove just enough material to reach the embedded item, whether it’s just below the surface or several feet down.

We worked with one contractor who discovered a need to replace bolts on anchors that were embedded a metre into the concrete. Not wanting to create a large hole and concerned about potential damage to the surrounding concrete as well as the rebar and anchors themselves, he turned to hydrodemolotion.

His crew was able to cut circular

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CONCRETE REPAIR

REPAIRING EXISTING STRUCTURES Sometimes repairs or changes are required

for existing structures. For example, we had a contractor who needed to remove eight-foot-thick concrete pier on an active construction site for a hydropower plant.

His crew was able to remove 4,944 cubic feet (140 cubic metres) in just 53 days.

They averaged 141 cubic feet (4 cubic metres) per 12-hour shift. Once the demolition was complete, the contractor poured

Selective removal allows contractors to remove poor-quality material, leaving the sound concrete intact.

new concrete onto the bonding surface created by the hydrodemolition process.

The water’s impact creates a rough, irregular profile that is ideal for bonding, and since the surface has already been washed and prepped, there isn’t a need for additional steps like sandblasting.

COMPRESSIVE STRENGTH FAILURE Fixes that require productivity and precision are prime candidates for hydrodemolition, and nowhere is that more apparent than when facing compressive strength failure. Once a failure has been identified, the use of robot-controlled water jets allow for fast, targeted removal of the weak material without damaging rebar or jeopardizing the structural integrity of the remaining concrete. When removal is complete, workers are left with a bonding surface that will provide a lasting correction.

Keith Armishaw is the business development manager for Aquajet’s North American subsidiary. He has more than 25 years of industry and leadership experience.

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2022-03-08 3:38 PM

PHOTO: COURTESY OF AQUAJET

holes that were just large enough to free the anchors. Not only did he minimizing the amount of concrete removed, he was also able to get through the job quickly, correcting more than a dozen anchors over a span of 12 hours.

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