Posts Tagged ‘construction’
“Nothing is built on stone; all is built on sand”*…
(Roughly) Daily has looked before at sand: as a scarce resource, thus as a valuable commodity and an object of theft, and as a metaphor. In this excerpt from his book, The World in a Grain: The Story of Sand and How It Transformed Civilization, Vince Beiser makes the case that it is the most important solid substance on earth…
[Sand is] the literal foundation of modern civilization. … Sand is the main material that modern cities are made of. It is to cities what flour is to bread, what cells are to our bodies: the invisible but fundamental ingredient that makes up the bulk of the built environment in which most of us live.
Sand is at the core of our daily lives. Look around you right now. Is there a floor beneath you, walls around, a roof overhead? Chances are excellent they are made at least partly out of concrete. And what is concrete? It’s essentially just sand and gravel glued together with cement.
Take a glance out the window. All those other buildings you see are also made from sand. So is the glass in that window. So are the miles of asphalt roads that connect all those buildings. So are the silicon chips that are the brains of your laptop and smartphone. If you’re in downtown San Francisco, in lakefront Chicago, or at Hong Kong’s international airport, the very ground beneath you is likely artificial, manufactured with sand dredged up from underwater. We humans bind together countless trillions of grains of sand to build towering structures, and we break apart the molecules of individual grains to make tiny computer chips.
Some of America’s greatest fortunes were built on sand. Henry J. Kaiser, one of the wealthiest and most powerful industrialists of twentieth-century America, got his start selling sand and gravel to road builders in the Pacific Northwest. Henry Crown, a billionaire who once owned the Empire State Building, began his own empire with sand dredged from Lake Michigan that he sold to developers building Chicago’s skyscrapers. Today the construction industry worldwide consumes some $130 billion worth of sand each year.
Sand lies deep in our cultural consciousness. It suffuses our language. We draw lines in it, build castles in it, hide our heads in it. In medieval Europe (and a classic Metallica song), the Sandman helped ease us into sleep. In our modern mythologies, the Sandman is a DC superhero and a Marvel supervillain. In the creation myths of indigenous cultures from West Africa to North America, sand is portrayed as the element that gives birth to the land. Buddhist monks and Navajo artisans have painted with it for centuries. ‘Like sands through the hourglass, so are the days of our lives,’ intone the opening credits of a classic American soap opera. William Blake encouraged us to ‘see a world in a grain of sand.’ Percy Bysshe Shelley reminded us that even the mightiest of kings end up dead and forgotten, while around them only ‘the lone and level sands stretch far away.’ Sand is both minuscule and infinite, a means of measurement and a substance beyond measuring.
Sand has been important to us for centuries, even millennia. People have used it for construction since at least the time of the ancient Egyptians. In the fifteenth century, an Italian artisan figured out how to turn sand into fully transparent glass, which made possible the microscopes, telescopes, and other technologies that helped drive the Renaissance’s scientific revolution.
But it was only with the advent of the modern industrialized world, in the decades just before and after the turn of the twentieth century, that people really began to harness the full potential of sand and begin making use of it on a colossal scale. It was during this period that sand went from being a resource used for widespread but artisanal purposes to becoming the essential building block of civilization, the key material used to create mass-manufactured structures and products demanded by a fast-growing population.
At the dawn of the twentieth century, almost all of the world’s large structures — apartment blocks, office buildings, churches, palaces, fortresses — were made with stone, brick, clay, or wood. The tallest buildings on Earth stood fewer than ten stories high. Roads were mostly paved with broken stone, or more likely, not paved at all. Glass in the form of windows or tableware was a relatively rare and expensive luxury. The mass manufacture and deployment of concrete and glass changed all that, reshaping how and where people lived in the industrialized world.
Then in the years leading up to the twenty-first century, the use of sand expanded tremendously again, to fill needs both old and unprecedented. Concrete and glass began rapidly expanding their dominion from wealthy Western nations to the entire world. At roughly the same time, digital technology, powered by silicon chips and other sophisticated hardware made with sand, began reshaping the global economy in ways gargantuan and quotidian.
Today, your life depends on sand. You may not realize it, but sand is there, making the way you live possible, in almost every minute of your day. We live in it, travel on it, communicate with it, surround ourselves with it…
“Sand and Civilization,” from @VinceBeiser via @delanceyplace.
* Jorge Luis Borges
###
As we muse on minerals, we might note that it was on this date in 1913 that a famous “sand castle” (concrete building) was opened in New York City, the neo-Gothic Woolworth Building. Located at 233 Broadway in the Tribeca neighborhood of Manhattan, it was the tallest building in the world from 1913 to 1930, at a height of 792 feet; more than a century after its construction, it remains one of the 100 tallest buildings in the United States.
The Woolworth Building has been a National Historic Landmark since 1966 and a New York City designated landmark since 1983. The building is assigned its own ZIP Code, 10279, one of 41 buildings in Manhattan so “honored” as of 2019.
“Seek truth from facts”*…
China’s property sector is enormous, under tremendous financial strain– and, as Jeremy Wallace explains, a very big contributor to climate issues (e.g., construction on China accounts for 5% of global energy consumption)…
China has ended zero-Covid. The resultant viral tsunami is crashing through China’s cities and countryside, causing hundreds of millions of infections and untold numbers of deaths. The reversal followed widespread protests against lockdown measures. But the protests were not the only cause—the country’s sagging economy also required attention. Outside of a few strong sectors, including EVs and renewable energy technologies, China’s economic dynamo was beginning to stutter in ways it had not in decades.
Whenever global demand or internal growth faltered in the recent past, China’s government would unleash pro-investment stimulus with impressive results. Vast expanses of highways, shiny airports, an enviable high-speed rail network, and especially apartments. In 2016, one estimate of planned new construction in Chinese cities could have housed 3.4 billion people. Those plans have been reined in, but what has been completed is still prodigious. Hundreds of millions of urbanizing Chinese have found shelter, and old buildings have been replaced with upgrades.
The scale of construction has been so prodigious, in fact, that it has far exceeded demand for housing. Tens of millions of apartments sit empty—almost as many homes as the US has constructed this century. Whole complexes of unfinished concrete shells sixteen stories tall surround most cities. Real estate, which constitutes a quarter of China’s GDP, has become a $52 trillion bubble that fundamentally rests on the foundational belief that it is too big to fail. The reality is that it has become too big to sustain, either economically or environmentally….
The “Chinese real estate bubble” is the world’s problem: “The Carbon Triangle,” from @jerometenk in @phenomenalworld. Eminently worth reading in full.
Analogically related (and at the risk of piling on): “China must stop its coal industry“
* Chinese maxim, popularized by Mao, then Deng Xiaoping
###
As we get real about real estate, we might spare a thought for Deng Xiaoping; he died on this date in 1997. A Chinese revolutionary leader, military commander, and statesman, he served as the paramount leader of the People’s Republic of China from December, 1978 to November, 1989. Deng led China through a series of far-reaching market-economy reforms, earning him the reputation as the “Architect of Modern China”.
The reforms carried out by Deng and his allies gradually led China away from a planned economy and Maoist ideologies, opened it up to foreign investments and technology, and introduced its vast labor force to the global market, thus turning China into one of the world’s fastest-growing economies.
But China’s real estate bubble is a reminder that every solution can all-too-easily turn into the next problem.
“The Greek temple is the creation, par excellence, of mind and spirit in equilibrium”*…
Edmund Stewart outlines the requirements for building a Greek temple…
If, like me, you have ever wondered what goes into building a Greek temple, then fear not: I here present a list of everything you will need. Admittedly, when compared with the wonders made possible by Roman concrete or a mediaeval gothic arch, the hundreds of temples scattered across the Greek world may perhaps look a bit small. Yet they are certainly elegant, sometimes with a slender beauty typical of the Ionic order, or else the sturdy grandeur of the Doric. And, when examined closely, the process of building one may quickly become worryingly complex…
Indeed, as The Browser observes, it’s a challenge…
In brief: [one would need] quite a lot. An architect, obviously, though architects were relatively cheap in ancient Greece; ships to bring in the marble; a hundred slaves for heavy lifting; a dozen carpenters; six craftsmen per column to dress the facade; sculptors and painters for the ornamentation; a door-maker; and do be sure to order your floor-tiles well ahead of time, they may take two years to arrive..
A fascinating and entertaining read: “What You Need to Build a Greek Temple,” in @AntigoneJournal, via @TheBrowser.
* Edith Hamilton
###
As we contemplate construction, we might send carefully-excavated birthday greetings to Charles Thomas Newton; he was born on this date in 1816. An archaeologist, he excavated sites in southwestern Turkey and disinterred the remains of one of the seven wonders of the ancient world, the Mausoleum of Halicarnassus (at present-day Bodrum, Turkey). Newton joined staff of British Museum in 1840, where he helped to establish systematic methods for archaeology and ultimately became its first keeper (curator) of Greek and Roman antiquities.
“The world is bound in secret knots”*…
It’s knot easy, but it’s important, to understand knots…
From whimsical flower crowns to carelessly tied shoelaces to hopelessly tangled headphones, knots are everywhere.
That’s not surprising, as knots are quite ancient, predating both the use of the axe and of the wheel and potentially even the divergence of humans from other apes. After all, ropes and cords are practically useless without being tied to something else, making one of the most ancient technologies still remarkably relevant today.
But these tie-offs can be a problem, since knots actually decrease the strength of a rope. When a rope made up of multiple fibers is taut, those fibers all share equal portions of the load. However, the bending and compression where the knot forces the rope to curve (usually around itself, or around the thing it is tied to) create extra tension in only some of the fibers. That’s where the rope will break if yanked with too much force. And this isn’t a small effect: common knots generally reduce the strength of a rope by 20 percent for the strongest ones, to over 50 percent for a simple overhand knot.
Experience has taught surgeons, climbers, and sailors which knots are best for sewing up a patient, or rescuing someone from a ravine, or tying off a billowing sail, but until some recent research from a group at MIT it was hard to tell what actually makes one knot better than another…
Which knot is the strongest? “The tangled physics of knots, one of our simplest and oldest technologies,” from Margaux Lopez (@margaux_lopez_).
See also: “The twisted math of knot theory can help you tell an overhand knot from an unknot.”
###
As we understand the over and under, we might send constructive birthday greetings to John “Blind Jack” Metcalf; he was born on this date in 1717. Blind from the age of six, he was an accomplished diver, swimmer, card player, and fiddler. But he is best remembered for his work between 1765 and 1792 when he emerged as the first professional road builder in the Industrial Revolution. He laid about 180 miles of turnpike road, mainly in the north of England– and became known as one of the “fathers of the modern road.”
Just before his death, he documented his remarkably eventful life; you can ready it here.
“They swore by concrete. They built for eternity”*…
Understanding how the materials we use work– and don’t work– together…
For most of a red swamp crayfish’s life, cambarincola barbarae are a welcome sight. Barbarae – whitish, leech-like worms, each a couple of millimeters long – eat the swamp scum off the crayfish’s shells and gills, and in most cases improve the crayfish’s health and life expectancy. Together, barbarae and crayfish form a mutualistic symbiotic relationship. Both species benefit from their cohabitation, and barbarae have evolved to the point where their entire life cycle, from egg to adult, occurs while attached to a crayfish.
But their symbiosis is contextual – a tentative truce. Young crayfish (who molt their shells more frequently and therefore accumulate less scum) don’t need much cleaning, and will take pains to remove barbarae from their shells. And even when molting has slowed and a crayfish has allowed the symbiosis to flourish, there are limits to barbarae’s loyalty: If there isn’t enough food for them to survive, they’ll turn parasitic, devouring their host’s gills and eventually killing them.
Like symbioses, composite materials can be incredibly productive: two things coming together to create something stronger. But like crayfish and barbarae, their outcomes can also be tragic. Rarely are two materials a perfect match for each other, and as the environment changes their relationship can turn destructive. And when composites turn destructive – as was evident in the reinforced concrete when the Champlain Towers North were inspected back in 2018 – the fallout can be catastrophic.
The history of what we now call composite materials goes back many thousands of years. For modern consumers, the most common composites are fiber-reinforced plastics (the colloquial “carbon fiber” and “fiberglass”), but perhaps the first composites in history were reinforced mud bricks. The Mesopotamians learned to temper their bricks by mixing straw into them at least as early as 2254 BC, increasing their tensile strength and preventing them from cracking as they dried. This method continues around the world today.
But by far the most commonly used composite material in history is steel-reinforced concrete. Roman concrete usage started as early as 200 BCE, and almost three centuries later Pliny the Elder included a note about what appears to be high quality hydraulic concrete in his Naturalis Historiae. These recipes were subsequently forgotten, and the material largely disappeared between the Pantheon and the mid nineteenth century. Modern concrete involves some legitimate process control: limestone and other materials are heated to around 900° C to create portland cement, which is then pulverized and mixed with water (and aggregate) to create an exothermic reaction resulting in a hard and durable object. The entire process consumes vast amounts of power and produces vast amounts of carbon dioxide, and the industry supporting it today is estimated to be worth about a half a trillion dollars.
But in spite of the fortunes that have been invested in the portland cement process (as well as in a wide range of concrete admixtures, which are used to tune both the wet mixture and the finished product), the true magic of contemporary concrete is the fact that it is so often reinforced with steel – dramatically increasing its tensile strength and making it suitable for a wide range of structural applications. This innovation arose in the mid-nineteenth century, when between 1848 and 1867 it was developed by three successive Frenchmen. In the late 1870s, around the time that the first reinforced concrete building was built in New York City, the American inventor Thaddeus Hyatt noted a critical quality of the material: through some fantastic luck, the coefficients of thermal expansion of steel and concrete are strikingly similar, allowing a composite steel-concrete structure to withstand warm/cool cycles without fracturing. This quality opened up the floodgates, and in the 1880s the pioneering architect-engineer Ernest Ransome built a string of reinforced concrete structures around the San Francisco Bay Area. From there it was history.
More than any other physical technology, it is reinforced concrete that defines the 20th century. Versatile, strong, and (relatively) durable, the material is critical to life and industry as we know it. Reinforced concrete was the material of choice of Albert Kahn, who with Henry Ford defined 20th century industrial architecture; reinforced concrete is a key part of nearly every type of logistical infrastructure, from roads to bridges to container terminals; reinforced concrete makes up the literal launch pads for human space travel. It’s a critical component of power plants, dams, wind turbines, and the vast majority of mid- to late-twentieth century homes and apartment buildings. Its high compressive strength makes it ideally suited for footings and foundations; its high tensile strength lets it cantilever and span great distances easily.
But reinforced concrete is really only 140 years old – the blink of an eye, as far as the infrastructure of old is concerned. The Pantheon was built around 125 CE, by which time the Romans had been experimenting with concrete construction for well over 300 years. When we see the Pantheon, we’re seeing a mature method – a technology with full readiness, being used in an architectural style that’s tuned for its physical properties.
By contrast, even our most iconic steel-reinforced concrete buildings are prototypes…
Early on in the history of steel-reinforced concrete, it was known that the high alkalinity of concrete helped to inhibit the rebar from rusting. The steel was said to be sealed within a monolithic block, safe from the elements and passivated by its high pH surroundings; it would ostensibly last a thousand years. But atmospheric carbon dioxide inevitably penetrates concrete, reacting with lime to produce calcium carbonate – and lowering its pH. At that point, the inevitable cracks and fissures allow the rebar inside to rust, whereupon it expands dramatically, cracking the concrete further and eventually breaking the entire structure apart.
This process – carbonatation, followed by corrosion and failure – was often visible but largely ignored into the late twentieth century. Failures in reinforced concrete structures were often blamed on shoddy construction, but the reality is that like the crayfish and the barbarae, the truce between concrete and steel is tentative. What protection concrete offers steel is slowly eaten away by carbonatation, and once it’s gone the steel splits the concrete apart from the inside…
There are of course many potential innovations to come in reinforced concrete. Concrete mixtures made with fly ash and slag produce high strength and durable structures. Rebar rust can be mitigated by using sacrificial anodes or impressed current. Rebar can be made of more weather resistant materials like aluminum bronze and fiberglass. Or the entire project could be scrapped – after all, the CO2 emitted by the cement industry is nothing to thumb your nose at. Whatever we do, we should remember that the materials we work with are under no obligation to get along with one another – and that a symbiotic truce today doesn’t necessarily mean structural integrity tomorrow.
On composites, crayfish, and reinforced concrete’s tentative alkalinity: “A Symbiotic Truce,” from Spencer Wright (@pencerw), whose newsletter, “The Prepared” (@the_prepared), is always an education.
* Gunter Grass
###
As we delve into durability, we might recall that it was on this date in 315 that the Arch of Constantine officially opened. A triumphal arch in Rome dedicated to the emperor Constantine the Great, it was constructed of Roman concrete, faced with brick, and reveted in marble.
Roman concrete, like any concrete, consists of an aggregate and hydraulic mortar – a binder mixed with water (often sea water) that hardens over time. The aggregate varied, and included pieces of rock, ceramic tile, and brick rubble from the remains of previously demolished buildings. Gypsum and quicklime were used as binders, but volcanic dusts, called pozzolana or “pit sand”, were favored where they could be obtained. Pozzolana makes the concrete more resistant to salt water than modern-day concrete.
The strength and longevity of Roman marine concrete is understood to benefit from a reaction of seawater with a mixture of volcanic ash and quicklime to create a rare crystal called tobermorite, which may resist fracturing. As seawater percolated within the tiny cracks in the Roman concrete, it reacted with phillipsite naturally found in the volcanic rock and created aluminous tobermorite crystals. The result is a candidate for “the most durable building material in human history.” In contrast, as Wright notes above, modern concrete exposed to saltwater deteriorates within decades.
You must be logged in to post a comment.