Concrete On-Site August 2020

AUGUST 2020

SENSING A CHANGE

PHOTO: GIATEC

THE RISE OF WIRELESS SENSORS

IN THIS ISSUE: www.on-sitemag.com 33 Bridges in

need of a new lease on life | 38 Using the maturity method

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CONCRETE REPAIR

A New

LEASE ON LIFE More bridges entering old age mean more repair and upgrade projects

BY DAVID KENNEDY

I

t’s no secret that Canada’s population is aging. Fewer kids mean fewer young people, while extended life spans add to the number of seniors. Undeniably, it’s a bit more complicated than that, but the basic arithmetic is clear-cut.

And it’s a similar story for a key category of the country’s infrastructure.

About three-quarters of Canadian bridges were built before 2000. For several classes of bridge – arterial, collector and local – nearly half were built before 1970, according to the latest Canada Infrastruc-

ture Report Card, which draws on information compiled by Statistics Canada.

Considering the estimated service life of the average Canadian bridge is around 50 years, many are well into old age. Bridges don’t exactly turn grey, but with structures aging far faster than they’re replaced, wear and tear, as well as new load or safety requirements mean the market for repair and upgrade work is taking off.

In 2019, 12 per cent of Canadian bridges were in poor or very poor shape.

Another 26 per cent of bridges were in fair condition. It’s worth noting the asset category also includes tunnels, but with just 351 tunnels and some 47,000 bridges coast to coast, bridges make up the vast majority of the tally.

When comparing the figures to the previous report card, the extent of the work needed is manifest. The comparable study issued just three years earlier in 2016 rated only four per cent of Canadian bridges poor or very poor, with another 22 per cent marked as in fair condition.

To keep infrastructure in working order, repairs and upgrades will only become more important in the years ahead.

Daryl Heppner, the general manager

The Groat Road Bridge project required crews to dismantle essentially all of the original bridge’s superstructure.

PHOTO: GRAHAM CONSTRUCTION/CITY OF EDMONTON

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CONCRETE REPAIR

A novel gantry crane method was used to repair the 330-metre bridge.

at B.C.-based Polycrete says he is seeing more and more bridges being worked on – whether that be deck repairs or retrofits that bring older structures up to new benchmarks.

“Quite often, it’s the age of the structure,” he says. “So water gets into a crack and fluorides from the salts that they throw in the winter get down into the cracks and then attack the reinforcing steel, which causes corrosion of the reinforcing steel and ultimately causes what most people would consider a pot hole but it’s actually a structural delamination.”

This common issue on bridge decks often requires crews to sawcut and jack hammer out the concrete around the corroded bars, sandblast the rebar and fill the gap with high-strength concrete.

Coatings are then often applied to protect the repair. For less serious cracking, epoxy injection is a less invasive fix.

Replacing the bearing pads that sit on piers is another common type of repair, Heppner says, though Polycrete’s main focus is on upgrade projects that rely on carbon fibre reinforcement.

“Not all bridges were designed for the loads that they’re carrying nowadays, so we do what we call carbon fibre strengthening to bring up the load capacity of these bridges,” he says.

Jeewan Khabra, the Structural Strengthening division manager at Polycrete, has worked on a range of repair work coast to coast, as well as structural and seismic bridge enhancement projects.

Currently, his focus is on employing fibre

34 / AUGUST 2020

“Not all bridges were designed for the loads that they’re carrying nowadays, so we do what we call carbon fibre strengthening.”

– Daryl Heppner, Polycrete reinforced polymer (FRP) composites.

“The use of those lightweight to highstrength tension members supplement the steel that the client or the engineer of record wishes was in that structural element,” he says, adding that employing the composite systems enables his team to change the structural capacity of certain elements of a bridge without touching the rest of the structure.

For instance, instead of adding steel or concrete to a beam or pier to increase its capacity, which often has a cascade effect that mandates upgrades to adjoining components to transfer the additional load, the FRP approach can be more precise.

“It gives you the same structural capacity as the conventional means of adding that steel and concrete, but because it’s lightweight, all I have to do is attack that column or attack that little section of the beam and you’re up to code,” Khabra says.

While costs of the composites haven’t necessarily changed in recent years, Khabra

says the savings on time, logistics and other related factors such as lane closures can be substantial, making the approach appealing to governments and other owners.

Along with increases to bridge load ratings, seismic upgrade projects are also increasingly common on Canada’s West Coast, as B.C. addresses the threat earthquakes pose to its infrastructure.

Balraj Mann, the chairman of Polycrete’s parent firm BM Group, is also bullish on the repair market.

“All over the world as the infrastructure ages, there’s more repairs required for regular maintenance,” he says.

While deck repairs and upgrades relying on FRPs are commonplace, in some cases, far more extensive repairs are required.

One such case is an ongoing project in Edmonton to rehabilitate the Groat Road Bridge, which crosses the North Saskatchewan River west of downtown. The four-lane span was built in 1955, and the latest rehabilitation work is expected to extend its lifespan 50 years.

Unlike the average repair, essentially the entire superstructure of the Groat Road Bridge is being torn down and replaced.

Deck joint issues, problems with the aging bridge’s rocking pier design and its failure to meet Alberta’s design shear requirements for heavy truck loads, were among the list of deficiencies that prompted the project, according to the City of Edmonton.

The original concrete piers will remain, with crews patching and sealing damaged areas, as well as strengthening the bases of several of the support structures.

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CONCRETE REPAIR “We did the majority of the cutting in the dead of winter.

It makes things incredibly difficult.

We cut with water, so everything’s got to be cooled with water. Water freezes at below zero. It was extremely challenging in that way.”

– Dave Moodie, CanWest Simply rebuilding the bridge up or downriver was also not an option because of the sensitive environmental and historical surroundings, the city said. To make the work even more challenging, two lanes of traffic needed to remain open during construction to avoid “significant” detours for the roughly 40,000 vehicles that cross the bridge each workday.

Graham Group Ltd. was awarded the $48 million contract to take on the project in 2018 and has spent more than two years on the complex fusion of demolition and reconstruction. Among other steps, the company has employed a new-to-Canada process that utilizes a pair of gantry cranes running on a steel runway that extends across the whole 330-metre bridge.

Dave Moodie, the general manager of CanWest Concrete Cutting and Coring Inc., which worked on the demolition component of the project as a subcontractor, said the project called for a piece-by-piece dismantling of nearly the entire bridge.

“Slab decks were cut out in between each girder throughout the entire length of the bridge, and then we would wiresaw the girders out,” he says.

Run through a series of pulleys, the use of multiple wiresaws on the bridge was another novel aspect to the project, Moodie says.

Among other hurdles, he pointed to the frigid Edmonton winters – with tempera-

tures dropping to as low as -40 C – as major obstacles.

“We did the majority of the cutting in the dead of winter,” he says. “It makes things incredibly difficult. We cut with water, so everything’s got to be cooled with water. Water freezes at below zero. It was extremely challenging in that way.”

Crews finalized work on the western

portion of the bridge last fall and shifted to the east side of the structure, starting with demolition, this January. Despite the cold and other uphill climbs, crews are on-track to complete the Groat Bridge project this fall.

With Canadian infrastructure continuing to get on in age, there will be many similar projects to follow.

The Advantage is

Safety vacuworx.com on-sitemag.com / 37

CONCRETE REPAIR

Sensing a change Concrete sensor technology gaining acceptance as contractors look to the future

BY DAVID KENNEDY

Kryton’s Maturix sensors use low-cost thermocouple wires as the sacrificial component.

PHOTO: KRYTON INTERNATIONAL

38 / AUGUST 2020

B

reaking concrete cylinders to test the compressive strength of concrete is standard practice for a reason. It’s relatively simple, cheap and when done right, accurately reflects strength. At the same time, break tests have changed little for decades and this lack of innovation is catching up with

the commonplace method.

Propelled by lower cost electronic components and improved connectivity, a new wave of wireless sensors, capable of delivering the same metrics as break tests – but doing so in real-time – is carving out an increasing share of the market.

Not needing a technician to collect field-test cylinders and lug them to the lab is just one small part of the value proposition, says Aali Alizadeh, co-founder, president and CTO of Ottawa-based Giatec Scientific Inc. The company first introduced its SmartRock sensor five years ago and the tiny wireless devices are now encased in concrete on more than 6,000 job sites worldwide.

“Things have not changed in a long time and the new generation of engineers are demanding technology,” Alizadeh says, adding that once concrete crews try out the sensors, there’s no going back. “‘Why have I been breaking cylinders throughout my career?’” he says, is a question he has heard over and over.

With the ability to measure both concrete temperature and strength in real-time, Kris Till, technical sales manager for Kryton International Inc., sees sensors coupled with cloud technology as the next evolution for the concrete industry.

“In a lot of infrastructure and pretty

much all big mass concrete pours, there is a need to understand, record and log temperature data,” he says. “We’re finding for a lot of contractors involved in these projects, this is a really easy way for them to be able to log the data better.”

“The strength development piece is really critical [too] because it can add so much benefit and so much time savings to the project,” he says.

Like other sensor technologies, Kryton’s Maturix sensors use what’s known as the maturity method to calculate strength.

The process plugs a range of data points gathered by the sensor, such as time and temperature, into an equation and calculates maturity via the cloud.

Though it’s a relatively new offering for the Vancouver-based company, best known for admixtures, Till says the market response to Maturix has been enthusiastic.

Kryton acquired a 30 per cent share in Denmark’s Sensohive Technologies ApS last fall in a deal that granted it exclusive North American distribution rights.

It’s not the only company moving into the space.

Power tool and fastener maker Hilti has also recently stepped into the sensor market. This March, it purchased substantially all the assets of Boston start-up Concrete Sensors, adding the entire

Hilti Concrete Sensors typically record an up to 10-x return on investment.

PHOTO: HILTI

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CONCRETE REPAIR

PHOTO: GIATEC

The latest version of Giatec’s SmartRock sensor boosted the wireless signal strength and made on-site activation simpler.

Concrete Sensors team to its Anchors division.

Scott Rutledge, Hilti’s business unit manager for Anchors, says the purchase fits well with the company’s goal of providing contractors new tools to improve job site performance.

“Concrete cylinders, while industry accepted and fantastic for determining what the concrete strength is on the day the cylinders are broken, are generally inadequate for helping the general contractor move faster,” he says. “And in the end, moving faster means less days on the job.”

THE CHANGING WORK SITE For Brendan Dowdall, who co-founded Concrete Sensors in 2015 and now serves as its director under the Hilti banner, the push toward the technology came when working as a general contractor. Unable to keep track of the metrics he wanted at his disposal when pouring concrete, he set out to find a better way to collect them.

The solution starts with the sensor itself. Before the pouring process, the wireless device, which the company calls NovoConcrete, is fastened to the rebar.

Crews then carry out their pour as normal, fully embedding the sensor in concrete.

Hilti Concrete Sensors makes two different versions – one that transmits temperature, strength and relative humidity

data to a phone or tablet via Bluetooth, and another designed for longer range that sends the metrics to a hub station, which in turn, transmits them to the cloud. Neither requires wires.

“Wires can sometimes be clipped, or accidentally stepped on and you can have higher failure rates,” Dowdall says. “By going completely wireless, you can increase that reliability and save headaches.”

Though this also means sacrificing the sensor, he says lower hardware costs over the past 10 to 15 years make entombing the sensor a small price to pay for the data provided. The real-time information often lets contractors move on to the next stage of work instead of waiting for lab confirmation their concrete has reached the required strength.

Along with pulling the data into a cloudbased analytics platform, Hilti Concrete Sensors also tests contractors’ mixes in its lab to better ensure its providing accurate strength data.

All jobs are different, Dowdall notes, but says the company’s technology typically records up to a 10-x return on investment.

Time and labour make up the bulk of the savings, but the efficiency gains can also translate to more work.

“If [contractors] can go into a project during bid or estimating and instead of saying that the concrete’s going to take

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www.kryton.com Toll Free: 1.800.267.8280 on-sitemag.com / 41

OnSite_Kryton_Aug20.indd 1

2020-07-30 9:45 AM

CONCRETE REPAIR

Typically, wireless sensors record a range of data points, plug them into an equation, and calculate maturity via the cloud. PHOTO: KRYTON INTERNATIONAL

six weeks, now it’s only going to take four weeks, that gives them a strategic advantage,” he says.

With Maturix, Kryton has taken a slightly different approach. The system puts similar information into the hands of contractors, but uses low-cost thermocouple wires as the sacrificial component. One end of the wire is secured in concrete during the pour, while the other is connected to reusable sensors/transmitters that automatically send data to the cloud.

Running on Sigfox’s 0G network, well known for its use in the IIoT space, the sensors can keep on- and off-site staff dialled into progress, ensuring quality and letting managers move up work when concrete has reached strength.

Till says the use of thermocouples lets contractors set multiple sensors in different areas of a pour without worrying about the cost.

“The limitation of the technology to date has really been the fact that a lot of the devices on the market are single-use devices,” he says. “So you’re taking a fairly expensive sensor and you’re burying it in concrete and it’s gone. So, it was limited as to how much you can use it.”

Along with the schedule-related benefits, Till says nearly everyone using the

42 / AUGUST 2020

sensors for the first time is able to quickly identify new ways to work smarter. One contractor, for instance, quickly realized he was overpaying for his concrete. “He was buying a mix design that was high early strength when he didn’t need it,” Till says.

“He was getting strength well before his schedule allowed.”

Now in their third generation, Giatec’s SmartRock sensors also continually send concrete data to the cloud, but do so while entirely embedded in concrete.

Alizadeh acknowledges costs can be higher compared to reusable systems, but he says the peace of mind of knowing the data is secure offsets the added investment.

“The value in time and ease of use is so high, especially for contractors who are on a tighter schedule, it doesn’t really matter,” he says.

For the latest version of the sensor, released earlier this year, Giatec boosted the wireless signal strength by about five times, made on-site activation simpler and enhanced its cloud dashboard to give contractors more details on about performance at each stage of projects.

And though it’s fixated on concrete, Giatec is also looking at projects as a whole.

“The concrete data is a small piece of

“Concrete data is a small piece of the puzzle... It’s a no-brainer for us we need to bring this concrete data as part of those [project management] platforms so they can see in one single dashboard all their data and make more informed decisions.”

– Aali Alizadeh, Giatec the puzzle,” Alizadeh says. “On a construction project, there’s so much going on. The project managers, the superintendents, their daily activities involve collecting all kinds of data.”

“They have project management software, like Procore, to record and capture and communicate that. It’s a no-brainer for us we need to bring this concrete data as part of those platforms so they can see in one single dashboard all their data and make more informed decisions as quickly as possible.”

Among other platforms, the company integrated with Procore in 2018, and it released its application programming interface (API) to allow other software tools to integrate more easily with its sensors last year.

As contractors look increasingly to technology to cut down on labour and trim costs, Alizadeh sees concrete sensors becoming a standard tool on job sites.

Likewise, Till says the demonstrable benefits of sensors are beginning to tip the scales. He doesn’t anticipate crush tests disappearing overnight, but says the growing industry awareness of sensors – and the maturity method – are shifting the industry toward accepting a new way of keeping tabs on strength.