Throwback Thursday: Proof testing bridges with living subjects

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It sounds crazy now. In an era when iron bridges routinely collapsed under the weight of marching soldiers, the builders of a high-profile exhibit hall chose to prove the sturdiness of their elevated iron walkways by . . . marching soldiers across one. And running them across it. Oh, and having 300 construction workers jump up and down on it, in unison, “for some time.”

Why did they think this was a good idea? And what was the result?

To illuminate this historical nugget, we spoke with Henry Petroski, an expert in failure analysis. A professor of civil engineering and history at Duke University, Petroski included the anecdote in his book To Engineer is Human: The Role of Failure in Successful Design.

A cathedral to progress . . . but would it hold up?

To be clear, the exhibit hall in question was quite innovative in many ways. The Crystal Palace (below) housed the first World’s Fair, in London in 1851. Its soaring glass-and-iron design was like nothing ever seen then. (Almost a horizontal skyscraper, it continues to influence design today.) Cutting-edge tools such as circular saws and steam-driven drills were used in the palace’s construction.

crystal_palace_-_interiorBut as impressive as the Crystal Palace appeared, contemporary Britons raised questions about the strength and stability of the temporary structure, especially its elevated walkways. “After all, during this time iron railway bridges were failing at a rate of almost one in four, and suspension bridges were collapsing under marching soldiers,” wrote Petroski. “The safety of the Crystal Palace galleries had yet to be demonstrated.”

And so, “a 24-foot-square section of gallery was constructed just off the floor on four cast-iron girders,” Petroski wrote. Queen Victoria and the press were invited to witness a proof test. The project’s 300 tradesmen and laborers were assembled, along with a company of sappers and miners (the British military’s engineering corps).

Let’s pause here a moment. Petroski has studied design failure for decades, and he has many thoughts on pedestrian walkways. “I think they’re not taken as seriously, perhaps, as they should be, because the load is considered lighter” than vehicles, he told us. “But when you jam people shoulder-to-shoulder on every square foot of a bridge,” as happened, for example, during the 50th anniversary celebration on San Francisco’s Golden Gate Bridge in 1987, “it’s actually far heavier even than bumper-to-bumper [auto] traffic.” In that case, he said, “the bridge visibly sagged in the middle.”

As to the temporary walkways inside the Crystal Palace in 1851, here’s what happened, according to the London Illustrated News:

The first experiment was that of placing a dead load of about 42,000 lb., consisting of 300 of the workmen of the contractors, on the floor and the adjoining approaches.

The second test was that of crowding the men together in the smallest possible space; but in neither case was there any appreciable effect produced in the shape of deflexion. So much for dead weight.

The third experiment—which was that of a moving load of 42,000 lb. in different conditions—consisted in the same party of workmen walking first in regular step, then in irregular step, and afterwards running over the floor, the result of which was equally satisfactory.

The fourth experiment—and that which may be considered the most severe test which could possibly be applied, considering the use to be made of the gallery floors when the Exhibition is opened to the public—was that of packing closely the same load of men, and causing them to jump up and down together for some time: the greatest amount of deflexion was found to be not more than a quarter of an inch at any interval.

The third experiment was then repeated, substituting, however, the Sappers and Miners engaged at the works, for the workmen of Messrs. Fox, Henderson, and Co.; and this last trial, which was quite as satisfactory as the others to all present, is represented in our illustration [below].

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Girding for success

So the walkway held up. How had the palace’s structural engineers been so sure they would avoid embarrassment—and their men would avoid injury—in the presence of their queen and London’s reporters?

As it turns out, the engineering team had tested, individually, all cast-iron girders to be used in the palace and walkways, with a brand-new machine invented specifically for the project. “The ordinary means of testing girders, by loading them with weights, would have occupied far too much time,” according to the fair’s official chronicle. A Mr. C.H. Wild devised “an ingenious apparatus” to accomplish the task in a few minutes (per girder).

hydraulic-pressWild’s apparatus (above) built upon technology developed by Joseph Bramah in the 18th century, and prefigured today’s universal testing machines. It was a hydraulic press that used pistons to squeeze girders “precisely at those points, and in the same manner, as the load from the gallery or the roof would do.” Using the press, Paxton’s engineers calculated that the gallery girders would withstand a pressure of 15 tons, while they estimated that the girders would only be subject to a pressure of 7.5 tons.

Making a circus out of it

The proof test with the jumping and the sappers and miners, then, was done largely for the benefit of the press, said Petroski. And if that sounds risky, get a load of this: “Sometimes bridge designers would walk elephants across them,” Petroski said. For example, in 1874, a test elephant lumbered across the Eads Bridge, over the Mississippi at St. Louis. A decade later, the famous Jumbo did the honors at the Brooklyn Bridge. “It was a mixture of publicity and practicality and superstition.”

The more common way to test bridges back then evokes a classic Calvin and Hobbes strip.  “Once the structure was completed,” said Petroski, “very heavy railroad engines or something equivalent would be driven across the bridge to, quote-unquote, ‘prove’ it would handle the load. That’s a long tradition in bridge-building. And in fact, in Eastern Europe, the engineer who designed the bridge would stand under it—sometimes even with his family—to show this was a solid design that he had all the confidence in the world about.”

But lest you think such stunts are wholly outdated, Petroski pointed to the Millennium Bridge in London. The pedestrian bridge across the Thames opened in June 2000. It swayed noticeably, and was closed three days later. After shoring up the bridge, engineers held a successful test with a hundred volunteers walking over it in 2002.

Lock and load

Nevertheless, in 2017, you probably won’t see human (or elephantine) subjects proof-testing a new structure. Today’s engineers test individual girders and other structural elements before assembly and use the results to calculate the maximum load—as the Crystal Palace team did. But if the public demanded further proof after assembly nowadays, engineers would conduct a load test with simulated human weight.

“They often do ‘drop tests’ with elevators,” said Suffolk Northeast Regional Safety Director Martin Leik, “to test that they can handle the weights they are to be loaded with when in full use.” These are “artificial weights,” noted Leik. “No one would even think about using real human beings for something like this now.”

Well, that is a relief. You might even call it a weight off the shoulders.

Final note: want to learn more about failing bridges? Petroski’s latest book, The Road Taken: The History and Future of America’s Infrastructure, was just released in paperback last week. It’s more timely than ever now.

This post was written by Suffolk Construction’s Content Writer Patrick L. Kennedy. If you have questions, Patrick can be reached at PKennedy@suffolk.com. You can connect with him on LinkedIn here or follow him on Twitter at @PK_Build_Smart.

Can you tell which roof has hidden solar panels?

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Would you believe all of them? Meet integrated rooftop solar.

In the dark of winter, when days are shortest, those of us in northern climes long for the sun. What better time to think about capturing and storing that sun’s energy? Solar electric power has been around for decades, and advances in the technology keep making it more efficient and practical. But for many, the desire to cut the household carbon footprint is tempered by aesthetic concerns. Rooftop solar panels don’t exactly look pretty, unless you’re going for Wall-E-meets-Windows chic.

Enter Tesla Motors. Not just a car company anymore, Tesla recently acquired SolarCity, the nation’s largest solar service provider. And the combo’s flagship product? A solar roof. It’s an array of photovoltaic panels, custom installed, that looks pretty much just like an ordinary roof. It will come in styles including slate and Tuscan tile. And with the star power of CEO Elon Musk, this product with curb appeal just might do for solar rooftop panels what Tesla has done for electric cars—make them cool. All part of the company’s professed mission: to accelerate the world’s transition to sustainable energy.

Musk unveiled the roof last fall at a shareholders’ meeting held in Universal Studios’ backlot. Investors gathered on a street that has served as the generic suburban setting for TV fare from Leave it to Beaver to Desperate Housewives. To hit the market some time this year, the panels are printed with the shingle-looking designs in a process called hydrographic coloring. They’re made of exceptionally durable tempered quartz glass. See how the material holds up compared to conventional roofing tiles:

Hidden underneath the glass are photovoltaic cells that will harvest the sun’s rays, feeding the energy to Tesla’s Powerwall 2 battery. The company says the battery can power an average two-bedroom home for a full day.

“It looks viable,” said Josh Rollins, LEED AP BD+C. “If it is, it’s a total game-changer.” A senior manager of marketing at Suffolk Construction, Rollins is also a leading member of the company’s Green Committee. “Elon Musk reminds me a bit of Steve Jobs in the way that he hypes his products, but this one is particularly exciting for anyone who’s passionate about reducing their carbon footprint,” Rollins said.

Musk’s presentation lacked some details, but flurries of informed speculation on the part of industry professionals help fill in the blanks. The biggest question to many is the roof’s cost. Musk says Tesla’s system will be cheaper than a traditional roof, when you factor in projected savings on your utility bill over the Tesla roof’s lifetime (50 years).

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Image courtesy of Tesla

How could Tesla achieve that lower price tag? For one thing, the quartz glass is a fifth as heavy as typical roofing materials; meaning lower shipping costs. For another, Musk hinted that he’ll cut out middlemen in the current roofing supply chain, with Tesla doing the installations itself.

All that said, the cost of a traditional roof plus the cost of grid electricity is quite steep, so even a figure smaller than that sum will likely still be large. Consumer Reports put the total as high as $70,000, too much for many homeowners to bear up front. Will the company offer financing? What if a homeowner defaults on the loan? Will Tesla rip the roof off and take it back? Unclear as of yet.

But Tesla’s entry into the residential solar market can only be a good thing if you’re rooting for the environment. As many as five million roofs per year need to be replaced. If you need a new roof anyway, why not make it one that will save you money on utilities? At least a certain segment of homeowners will be able to afford the premium Tesla product. And for those who can’t, Tesla’s announcement should bring more attention to other, relatively affordable integrated rooftop solar products.

That’s right, Tesla has competitors in this niche—companies like SunTegra and CertainTeed. Though none of their solar products are quite as invisible as Tesla’s, many are pretty darn unobtrusive, especially compared to the standard rack-mounted panels. (Check out the examples below.) These companies welcome the new publicity. “I have to agree with Elon Musk: the future for roof integrated solar is bright,” wrote SunTegra CEO Oliver Koehler in a trade publication. “It’s going to be an exciting next couple of years.”

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Image courtesy of CertainTeed

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Image courtesy of SunTegra

What we really look forward to is learning whether the integrated technology can be scaled up to apartment complexes, and perhaps to even bigger projects—maybe even high-rises. After all, said Rollins, “Why stop at the roof?” Rollins recalled a previous Build Smart blog post about harnessing solar energy with windows, something a skyscraper in Australia plans to do. “Why not cover the skin of the entire building in solar panels? That’s another whole surface area that could be generating electricity,” Rollins said.

Perhaps we can yet break our addiction to supply-limited fossil fuels, thanks in part to visionaries such as Musk. Heck, the last time a Tesla release made us this optimistic, it was an awesome late-1980s power ballad. Here’s to solar finding a way.

This post was written by Suffolk Construction’s Content Writer Patrick L. Kennedy. If you have questions, Patrick can be reached at PKennedy@suffolk.com. You can connect with him on LinkedIn here or follow him on Twitter at @PK_Build_Smart.

A building’s skin and bones—literally? The coming world of engineered living materials

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When lightning strikes, a tree can often repair the damage by generating another layer of bark to cover the gash. But if that same bolt from above lashes a wood-frame house instead, call the remodelers. Even though the house’s exterior walls are essentially made of trees, the material lost its adaptive quality when lumberjacks felled those mighty pines or oaks.

In the words of scientist Justin Gallivan of the U.S. Defense Advanced Research Projects Agency (DARPA), wood is “rendered inert” when a tree is chopped down. That neutralizes all the advantages of a living material. In their natural state, trees react and adapt to wounds and the weather. So do coral reefs—not to mention your own skin.

What if living materials, with those same self-healing properties, could be grown artificially to the size and strength required to construct a house? Or a skyscraper? Is that possible? That’s what DARPA wants to find out. The agency is soliciting research proposals aimed at the creation of what it calls “engineered living materials (ELM).”

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DARPA envisions walls that fix themselves, non-fading surfaces, and driveways that absorb oil spills without a trace. (Source: DARPA)

“Imagine that instead of shipping finished materials, we can ship precursors and rapidly grow them on site using local resources,” Gallivan said to the press in August when announcing the ELM program. “And, since the materials will be alive, they will be able to respond to changes in their environment and heal themselves in response to damage.”

Today, a building’s envelope is often called its “skin,” while the steel frame of a building is known as its skeletal structure, or even its “bones.” In DARPA’s imagined future, these terms will cease to be merely rhetorical. And the sustainability benefits of bio-building might be substantial, when you consider the carbon emissions generated in the production of conventional materials such as concrete.

But DARPA didn’t pull this sci-fi-sounding concept out of thin air. Biochemists and engineers around the globe are already tinkering with limited forms of biomimetic (or life-imitating) materials, as you’ll see below. Gallivan’s vision of self-healing living walls is perhaps the logical extension of these various technologies, and the ELM program might prove the catalyst needed for skin-and-bone to replace brick-and-mortar.

Bacteria brickyard

One inspiration for the ELM program is a start-up that grows bricks in a lab. Yes, grows. The idea occurred to architect Ginger Dosier when she learned that coral polyps—tiny marine animals—create the hard, rocklike substance sandstone naturally. She co-founded the company, bioMASON, with her husband, Michael—like her, an architect and a self-taught scientist. (They have help from a staff of college-taught scientists.)

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The lab-grown bricks. (Source: bioMASON)

In their lab in North Carolina’s Research Triangle, the bioMASON team places sand into molds and injects it with trillions of microorganisms (Sporosarcina pasteurii, if you must know), which they feed water and a calcium solution. The bacteria bind with the grains of sand, generating a natural cement that becomes heavy and hardens. The bricks are ready in two to five days.

Compare that with the way traditional bricks are manufactured, by digging up clay (which could be better put to use in agricultural soil) and firing it in a kiln at 2,000 degrees for three to five days. This process uses up lots of fuel and releases carbon dioxide into the atmosphere—800 million tons of it per year, by some estimates. Keep in mind, brick is still the most common building material worldwide, with Asia alone making 1.2 trillion bricks a year.

According to Acorn Innovestments, which provided bioMASON with seed funds, third-party testing determined that the bio-bricks have a strength comparable to traditional masonry, though for now, the start-up is only selling the bricks for use in paving. The bioMASON lab can produce 1,500 bricks a week, and they’re moving next month to a larger facility that will enable them to make 5,000 bricks every two days.

But the Dosiers hope to truly make an impact by shipping the bacteria solution—just one hand-held vial can make 500 bricks—across the globe to builders who can mix it with local sand, whether from nearby deserts (looking at you, Los Angeles) or quarries. Continue Reading ›

Throwback Thursday: Builders at war

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We promise to get back to cutting-edge and futuristic construction technology with the next post, but this week, to observe Veterans Day, we’re highlighting the vital supporting role that America’s builders played in the world wars of the last century.

“Victory seems to favor the side with the greater ability to move dirt.” That’s how Major General Eugene Reybold, head of the U.S. Army Corps of Engineers (USACE), described the success of his men in the Second World War.

There’s more to a war than shooting. Troops need to move great distances across an often uncooperative landscape, and the USACE—composed largely of experienced engineers, contractors, tradesmen, and laborers—have helped move, supply, and protect those troops by building roads, bridges, dams, forts, ports, depots and barracks in the nation’s various conflicts since 1775. (That’s in addition to the Corps’ many valuable peacetime projects.)

“American construction capacity was the one factor of American strength which our enemies consistently underestimated,” Reybold continued, in 1944. “They had seen nothing like it.”

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Members of the 1st Engineers building a trench revetment in France in 1918. (Photo courtesy of the National Archives)

Actually, the Germans already had a taste of American mettle a generation prior, during the final phase of the First World War. In 1917 and 1918, the engineers built dams and pipelines, opened up quarries, chopped down tons of timber, built bridges, and graded, repaired or built and maintained hundreds of miles of roads and railways across the mortar-pocked fields of France. Their work allowed hundreds of thousands of Yankee “doughboys” to travel by foot, horse, tank and truck the length of the country.

The engineers performed this work around the clock, through rainstorms, sometimes knee-deep in mud or neck-deep in water. Moreover, they often labored under enemy fire. In fact, the first two U.S. Army casualties in Europe were members of the 11th Engineers serving outside Cambrai, France in September 1917. And the Distinguished Service Cross was awarded to four soldiers from the 7th Engineers who helped construct a pontoon bridge across the Meuse River under fire in November 1918. Three of them jumped into the icy water to hold up a deck by hand until replacement floats could be installed, after a German artillery shell destroyed one section of the bridge.

That was just one of 38 bridges the engineers built as part of the Meuse-Argonne offensive, which ended with the Kaiser’s surrender. Indeed, building pontoon bridges with lightning speed was a specialty of the engineers during both world wars. For example, as part of the same offensive, the 2nd Engineers built a foot bridge over the Meuse River in under an hour. During the war’s bloody sequel, the 22nd Armored Engineer Battalion built a 330-foot-long bridge, capable of supporting a moving line of tanks and trunks, in three hours and two minutes—“about the time it takes to see a double-feature movie show,” as Popular Science put it.

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Pontoon bridge over the Meuse, 1918.

It was the kind of feat that could only be pulled off through a massive coordination of manpower and materials and under intense pressure. But how, specifically, did the men do it? Most commonly in WWI, they lashed together one sequence of pontoon boats, topped with wooden decking, between long wooden balks. They rowed this out into position, then followed it with another section, and so on until they reached the opposite shore. If the Army was short on standard steel-plated pontoons, then regular boats, canoes, and even empty wine casks stood in.

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U.S. Army tank and troops crossing the Rhine, March 1945.

During WWII, in many cases a higher class of pontoon bridge was strengthened with longer and sturdier pneumatic pontoons, inflated by motorized air compressors. The construction system was streamlined with a new generation of hydraulic cranes and boom crane trucks, swinging sections of steel treadway out over the water and lowering them onto the pontoons. The sections were bolted together, and the bridge as a whole was stabilized with 200-pound catch anchors. Other bridge types included the portable Bailey bridge, made of lightweight steel. (See video at bottom.) In a pinch, though, the old methods were still employed.

We should also note that during WWII, the Army engineers’ efforts in Europe were matched in the Pacific by the Naval Construction Battalions, a.k.a. the Seabees. In both theaters, the builders benefited from advances in bulldozer technology. Check out the two photos below, brought to our attention by the Journal of Light Construction.

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A Caterpillar dozer fills in bomb craters in Normandy, 1944. (Photo courtesy of the National Archives)

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Dozers in action in the Pacific in WWII. (Photo courtesy of Yale University Press/US NCB)

In both wars, once the firing stopped, the rebuilding began. The engineers filled in trenches and craters, blew up tank barriers, and tore down machine-gun nests. They charted and destroyed unexploded land mines, dismantled bundles of tree-branch camouflage, and resurfaced the roads that the victories Allies rode en route to Berlin.

As mentioned earlier, the Army engineers have also performed critical tasks in civil engineering during peacetime. The corps is known for designing and constructing dams, canals, flood protections, and wetlands restoration, among other projects Stateside.

So while doffing hats for all our veterans, if you get a chance tomorrow, thank a Seabee or an Army engineer. Often quite literally, they paved the way to a free world.

Click below to see vintage footage of the Army engineers—in training, in the Pacific, and in Europe—as they used old-school power shovels, dozers, and their own ingenuity to build roads, bridges, and airfields, often under enemy fire, during WWII:

This post was written by Suffolk Construction’s Content Writer Patrick L. Kennedy. If you have questions, Patrick can be reached at PKennedy@suffolk.com. You can also connect with him on LinkedIn here or follow him on Twitter at @PK_Build_SmartThe video, sourced from an archival U.S. Department of Defense film, was edited by Suffolk Construction’s Junior Videographer Danny Czerkawski. Danny can be reached at DCzerkawski@suffolk.com. 

Throwback Thursday: Turning the first sod

As work begins on the expansion of Suffolk Construction’s headquarters—which was celebrated with a high-tech virtual groundbreaking—we explore the ancient roots, and some colorful examples, of the groundbreaking tradition.

Like knocking on wood, crossing your heart, or crossing the street to avoid a black cat (particularly around Halloween), there are some rituals—rooted in antiquity, maybe in prehistory—that most of us carry on to this day, whether or not we consider ourselves superstitious.

So it is with the time-honored tradition of the construction-site groundbreaking ceremony. Just as a shipbuilder wouldn’t launch a craft without first smashing a champagne bottle on its prow, a developer might feel amiss were a structure to rise without a gathering of dignitaries and a plunging of shovels into earth at some early stage of the project. In a few cases, dynamite, sledgehammers, airplanes, or green smoke have been used to liven up the proceedings, as you’ll see below.

The precise origins of the groundbreaking—better known in previous decades as the “sod turning” or “turning the first spadeful of earth”—are obscured by the mists of time, but the ritual exists in nearly all cultures the globe over. In some ancient traditions, breaking the ground was considered an act painful to the earth, requiring a sacrifice to compensate. To take one gruesome example, centuries ago the Tlingit people of Alaska would kill slaves and bury them under the corner post of a new longhouse.

Less horrifying religious rites persist to this day. In India, homebuilders ask permission from Bhoomi (Mother Earth) before disturbing her. To restore equilibrium to the site, an elaborate series of rituals includes burying a box containing gold, silver, coriander seeds, a whole betel nut, and a stick of turmeric, among other items carrying significance.

In the same way, Japanese builders placate the local kami, or god of the land, and pray for the safety of the construction workers with a Shinto purification rite, known as a jichinsai. A priest marks off a sacred space with four bamboo poles and sets up an altar with offerings of food and sake, or rice wine, which is poured on the four corners of the construction site. Wooden tools are then used to break ground.

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An altar used during a Shinto rite to purify a construction site.

In the 1960s, a city assemblyman charged that this spectacle, at the site of a public gymnasium, violated the nation’s constitution (which, like ours, provides for the separation of church and state). The case went all the way to Japan’s supreme court, which found that the civic ceremony did not promote or subsidize the Shinto religion.

In Western nations, too, it’s been common in modern times for developers to invite priests or other clergy to offer a prayer or otherwise take part in a groundbreaking, despite our generally secular public life. As in Japan, old customs die hard. Besides, a little blessing can’t hurt!

And maybe builders should be a bit superstitious. The Panama Canal was initially, in the 1880s, a French undertaking. Count Ferdinand de Lesseps, in our terms the project executive, attempted a bicoastal ceremony: He turned the first sod on the Atlantic end of the planned canal, then traveled by train and boat to the Pacific end. But stormy seas—or too much champagne, according to one account—prevented de Lesseps from landing. He scheduled another ceremony, in which exploding dynamite would kick off the project, but the charge fizzled.

So did the project. That first canal effort ended in failure; the Americans later picked up where the French had left off.

Dynamite was used successfully to inaugurate the Long Island Parkway in New York in 1908 (“a stick of dynamite blew high in the air an impeding tree,” wrote one observer) and the Massachusetts Turnpike in 1962. (“I only wish some of my critics were sitting on top of that ledge,” said turnpike planner William F. Callahan before pressing the plunger and dissolving the offending ledge in a burst of green smoke.)

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Source: The Boston Globe

In Boston in the 1970s, the Lewis Wharf condo development began with a “water-breaking,” in which a huge anchor was lifted from the harbor, and one hotel owner let his 20-month-old granddaughter commence a project with a “sand-turning” in a sandbox.

For ceremonies in California, skydivers have floated to earth bearing golden shovels, and “a two-story replica of a personal computer emerged from the ground in a high-tech industrial park,” according to the L.A. Times. The mayor of Brea once started a project with a backhoe; the machine lurched wildly, scattering the assemblage.

Suffolk Construction Breaks Ground on HeadquartersHow far has the ritual come since the days of human sacrifice, or even green smoke? Pretty far, to judge by the virtual groundbreaking at Suffolk’s headquarters expansion (left). Boston Mayor Marty Walsh joined Suffolk executives in donning virtual-reality headsets and scooping dirt that existed only in a 3D video-game-style environment—visible to those wearing the goggles, and projected as well on a large screen for the benefit of the audience. With each shovelful of pixelated earth, a 3D model of the building-to-be would rise from the ground in stages, as if by magic.

As far as we know, this is the first time a virtual groundbreaking has been done. Can anyone tell us different? Or offer your own unusual or innovative takes on the ceremony? Let’s hear your comments!

This post was written by Suffolk Construction’s Content Writer Patrick L. Kennedy. If you have questions, Patrick can be reached at PKennedy@suffolk.com. You can connect with him on LinkedIn here or follow him on Twitter at @PK_Build_Smart.

If it’s broke, it’ll fix itself

How 200-year-old bacteria might heal the cracks in concrete

Concrete has been used in construction for thousands of years. Think of the Colosseum and the aqueducts of Ancient Rome. In the modern era, builders have sought to make improvements to the mixture’s strength, durability, and eco-friendliness. During the Industrial Revolution, engineers discovered better materials and faster ways to produce concrete. They began strength testing different mixes in 1836. The first concrete road in the U.S. was laid in 1891, and it handles modern auto traffic today. Recently, one company produced a concrete that locks in carbon dioxide as it dries. But through all these changes, one problem has remained unsolved: cracks.

These cracks start out small, but widen over time, which can make structures unstable: when water gets in the cracks, the metal rebar supports will rust and break. Workers can seal the cracks if they are spotted, but by then the damage could already be done, which leads to costly and time-consuming repairs. Even worse damage can occur if the cracks open in places where they won’t be noticed until it’s too late. To solve this problem, a new concrete revolution is under way. Someday, workers won’t have to inspect the dried concrete for cracks, because these cracks will seal themselves. That’s right—seal themselves!

Inspired by the way the human body heals itself after breaking a bone, Professor Henk Jonkers (pictured above) wondered whether it was possible to introduce healing abilities to a man-made material. As a microbiology researcher at Delft University in the Netherlands, Jonkers is particularly fascinated with bacteria. He began to envision embedding concrete with microscopic repairmen.

Knowing that bacteria produce limestone under certain conditions, he theorized that he could help cracks self-heal by adding a couple extra ingredients to the standard mix of sand, cement, and water. The first is a strand of bacteria called Bacillus, whose spores are sealed in biodegradable capsules. The other is the bacteria’s food source, calcium lactate. As a crack forms and water gets in, the water dissolves the capsules and activates the bacteria. The bacteria then consume the calcium lactate and produce limestone, which seals the cracks and protects the structure from further damage.

In the course of developing this concrete, several problems arose. The first was finding the right bacteria to use. Eventually Jonkers selected Bacillus because of its ability to survive in the high alkaline cement mix. Before being mixed into the concrete, the bacteria spores are placed in pods to prevent early activation, where they can survive for up to 200 years. These pods are made of a clay material that is weaker than the original concrete—that’s the second problem. To solve it, Jonkers and his team at Delft are now trying to pinpoint the highest percentage of the healing agent that can be added to the concrete mix before the strength and integrity of the structure is compromised. At the same time, the percentage
cannot be too low, or there might not be any healing agent in any given area where a crack appears.

Self-healing concrete is not in use yet, but scientists are optimistic that it will be soon, as reported in Smithsonian magazine. Right now the pricing is too high for most construction jobs, about double the cost per cubic meter, due to the high cost of calcium lactate. Jonkers hopes to get the cost down as the demand for his concrete increases, and he expects the product to be available in the next few years. Until then, cracks will continue to widen, unnoticed, until someone decides to fix them.

This post was written by Suffolk Construction’s Marketing Intern Morgan Harris. Connect with her on LinkedIn here.

The future of work: Physical office, remote … or something else?

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The following is the third and final post of our series on the office space of tomorrow. 

Screen Shot 2016-04-22 at 2.12.38 PM.pngAfter our past blog posts about expansive new office buildings built by innovative companies such as Google, Facebook and Apple, office furniture designs of tomorrow, and the future of cubicles, it might be time for us to step back and ask a question that might be on the minds of many commercial developers, architects and business leaders as they look toward the future — will the workers of tomorrow even need office space in the first place?

The jury is still out, but the most recent data gives us hints about where the future of office space might be heading. According to a January 2015 Gallup report called “State of the American Workplace,” almost 40 percent of full-time workers in the U.S. work remotely, and of these, approximately 15 percent are permanently out of the office, and those numbers continue to rise. And many of these workers are not necessarily working from home but are working in coffee shops, shared spaces and other outside-the-office locations, which shows that many people simply want a change of scenery outside the office. Another noteworthy Gallup study concluded that the most engaged employees in the workforce actually spend up to 20 percent of their time working remotely.

And The Muse reported that research conducted by Nicholas Bloom, a Stanford professor who studies workforce trends, confirmed that working remotely actually increases productivity, overall work hours, and employee satisfaction. Over a nine-month period, Bloom observed 250 employees at a Chinese company where half the employees worked from home and half worked in the office. The data from studies like these speak volumes. Bloom found that removing the time it takes to physically commute to work and the distractions of the in-office environment made a huge difference. People who worked from home completed 13.5 percent more calls than the office workers, performed 10 percent more work overall, left the company at half the rate of their colleagues who worked in the office, reported feeling more fulfilled at work, and actually saved the company $1,900 per employee.

With that many people working remotely, and working more productively, the need for more office square footage must be unrealistic, right? Karim Rashid is just one of many industrial designers who is raising that important question  — “We’re losing institutions, losing banks, colleges. Do we even need physical space anymore? What about the office context? Does it need to physically exist anymore or not?” Continue Reading ›