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Roman concrete from noblewoman’s tomb still stands strong 2,000 years later. Here’s why

The tomb of Caecilia Metella is still remarkably intact after nearly 2,000 years since it was completed. Credit: Tyler Bell.

One of the world’s biggest engineering problems is concrete. Critical infrastructure built over the last century — bridges, highways, dams, and buildings — are now crumbling before our eyes. Repairing and rebuilding this decaying infrastructure is estimated to cost trillions of dollars in the United States alone.

When steel reinforcements were introduced to concrete in the 19th century, it was rightfully at the time hailed as a massive step up in innovation. Adding steel bars to concrete speeds up construction time, uses less concrete, and allows the engineering of long, cantilevered structures such as miles-long bridges and tall skyscrapers. These early engineers who introduced these projects thought reinforced concrete structures would last at least 1,000 years. In reality, we now know their lifespan is between 50 and 100 years.

Concrete was originally developed by the ancient Romans, whose building techniques were lost with the fall of the empire and wasn’t reinvented until 1824 when an Englishman named Joseph Aspdin discovered Portland cement by burning finely ground chalk and clay in a kiln until the carbon dioxide was removed.

However, the durability of the two types of concrete is worlds apart. Many magnificent Roman buildings, such as the Pantheon, still stand proud even to this day after nearly 2,000 years.

In a new study, scientists describe another example that serves as a testament to the craftsmanship of Roman concrete, illustrating the case of a large cylindrical tomb that serves as the final resting place for 1st-century noblewoman Caecilia Metella.

Investigations performed by geologists and geophysicists at the University of Utah show that the tomb’s concrete is of particularly high quality and durability, even by Roman standards, surpassing that of the tombs for her male contemporaries.

The secret is the particular type of volcanic aggregate the Roman craftsmen use and a bit of luck owed to the fortuitous chemical interaction of rainwater and groundwater with these aggregates.

The concrete that outlived an empire

Caecilia’s tomb lies on the edge of the Appian Way, the famous ancient Roman road that connected Rome to Brindisi, in the southeast. The structure is monumental for its time, measuring 70 feet (21 meters) in height and 100 feet (29 meters) in diameter. It consists of a drum-shaped tower on top of a square-shaped base.

It was erected around the year 30 BCE, which means Caecilia must have passed away while Rome was still a Republic. Just a few years later, in 27 BCE, Octavianus Augustus, Julius Caesar’s nephew, proclaimed himself Emperor, opening up a new age for Rome.

Her imposing tomb is worthy of her status. The daughter of a wealthy nobleman, she married into the family of Marcus Crassus, probably the wealthiest man in the world at the time (and one of the wealthiest in history, relatively speaking) and the third member of the famous triumvirate alliance with Caesar and Pompey.

Marie Jackson, research associate professor of geology and geophysics at the University of Utah, first visited the tomb in 2006 with a permit from Italian archaeologists to collect a small sample of mortar for analysis. When she arrived at the site, she was stunned by the almost perfectly preserved brick masonry walls and the water-saturated volcanic rock outcrop in the substructure.

Now, in a new study, Jackson teamed up with colleagues from MIT and the Lawrence Berkeley National Laboratory to zoom into the microstructure of the tomb’s concrete using an array of modern tools at their disposal. These instruments include the microdiffraction beamline at the Advanced Light Source (ALS) that produces a “micron size, extremely bright and energetic pencil X-ray beam that can penetrate through the entire thickness of the samples, making it a perfect tool for such a study,” said co-author Nobumichi Tamura of Lawrence Berkeley National Laboratory.

Modern concrete mixes Portland cement— limestone, sandstone, ash, chalk, iron, and clay, among other ingredients, heated to form a glassy material that is finely ground — with aggregates, such as ground sand or rocks. These aggregates, usually sand or crushed stone, are not intended to chemically react because if they do, they can cause unwanted expansions in the concrete.

In contrast, Roman concrete didn’t use cement. Instead, they would make the concrete by first mixing volcanic ash, known as “tephra”, with limestone and seawater to make mortar, which is later incorporated into chunks of volcanic rock, the ‘aggregate’. Previously, while studying drilled cores of Roman harbor concrete, Jackson found an exceptionally rare mineral, aluminous tobermorite (Al-tobermorite) in the marine mortar. The mineral’s presence surprised everyone because it is very difficult to make. For Al-tobermorite to form, you need a very high temperature. “No one has produced tobermorite at 20 degrees Celsius,” she says. “Oh — except the Romans!”

Later, Jackson studied mortar from the Markets of Trajan and found a mineral called strätlingite, whose crystals block the propagation of microcracks in the mortar, preventing them from linking together and fracturing the concrete structure.

Roman concrete can actually grow stronger with time

Scanning electron microscopy image of the tomb mortar. The C-A-S-H binding phase appears as gray while the volcanic scoriae (and leucite crystals) appear as light gray. Credit: Marie Jackson.

At Caecilia’s tomb, the researchers were in for yet another surprise. The particular variety of tephra used in the ancient Roman structure was richer in leucite, a rock-forming mineral of the feldspathoid group. Over the centuries, rainwater and groundwater percolated through the walls of the tomb and dissolved the leucite, releasing its potassium into the mortar. The potassium dissolved and reacted with a building block in the mortar called C-A-S-H binding phase (calcium-aluminum-silicate-hydrate).

This remodeling led to a more robust cohesion in the concrete, despite much less strätlingite than seen in the Markets of Trajan.

“It turns out that the interfacial zones in the ancient Roman concrete of the tomb of Caecilia Metella are constantly evolving through long-term remodeling,” said Admir Masic, associate professor of civil and environmental engineering at MIT. “These remodeling processes reinforce interfacial zones and potentially contribute to improved mechanical performance and resistance to failure of the ancient material.”

If Roman concrete is so awesome, why don’t we still use it? There are many reasons why the ancient construction material is not at all feasible for our contemporary needs. Sourcing the kind of volcanic ash in the original recipe is not possible for much of the world, which now uses an estimated 4 billion tons of cement every year. Roman concrete also lacks the compressive strength required for modern huge infrastructure projects, among other things.

But that doesn’t mean there aren’t important lessons to be learned from Roman concrete that may help the next generation of concrete to overcome current shortcomings in our crumbling infrastructure. That’s exactly what Jackson and colleagues are set to do, part of an ongoing U.S. Department of Energy ARPA-e project. The objective is to find a new ‘recipe’ that could reduce energy emissions associated with concrete production by 85% and vastly improve the lifespan of the material.

The findings appeared in the Journal of the American Ceramic Society.

Self-healing concrete plugs cracks with CO2 sucked from the air

Examples of self-healing concrete whose cracks have been filled with calcium carbonate made from CO2 sucked from the air and catalyzed by a red blood cell enzyme. Credit: Worcester Polytechnic Institute.

Using an enzyme normally found in red blood cells, researchers have designed a concrete mixture that can automatically seal cracks in the construction material by absorbing CO2 from the air and converting it to calcium carbonate crystals. The resulting concrete is almost four times more durable than traditional concrete, vastly extending the life of structures and slashing the huge upkeep costs required for repairs or replacements.

Concrete with a touch of enzymes

Concrete is the most ubiquitous construction material in the world. We use it to build everything from skyscrapers to sidewalks due to its durability and low cost. However, concrete is far from perfect, being prone to cracking due to continuous exposure to the elements. Humidity, sunlight, and stress from use slowly chip away at concrete. Over time, harmless microcracks can expand and lead to a loss of structural integrity. In the case of dams and bridges, concrete cracks could threaten the lives of countless people.

“If tiny cracks could automatically be repaired when they first start, they won’t turn into bigger problems that need repair or replacement. It sounds sci-fi, but it’s a real solution to a significant problem in the construction industry,” said Nima Rahbar, associate professor of civil and environmental engineering at Worcester Polytechnic Institute.

Rahbar is the lead author of a new study that took inspiration from nature to find a solution to this problem. The research centered around carbonic anhydrase (CA), an enzyme found in red blood cells that quickly transfers CO2 from the cells to the bloodstream. 

The researchers simply added the enzyme to a conventional concrete powder before it was mixed with water and poured. These experiments showed that the enzyme acts as a catalyst, triggering a chemical reaction between atmospheric CO2 and molecules in the concrete to create calcium carbonate crystals.

Calcium carbonate is a common substance found in rocks such as the minerals calcite (a major component of limestone) and aragonite. It is also the main component of eggshells, snail shells, seashells, and pearls. Its atomic matrix is very similar to that of concrete, so when the calcium carbonate forms inside gaps in the concrete, the structural integrity of the material is preserved.

“We looked to nature to find what triggers the fastest CO2 transfer, and that’s the CA enzyme,” said Rahbar, who has been researching self-healing concrete for five years. “Since enzymes in our bodies react amazingly quickly, they can be used as an efficient mechanism to repair and strengthen concrete structures.”

According to Rahbar, the patented method described in the journal Applied Materials Today heals millimeter-scale cracks within 24 hours. You can see the process in action in the short clip below.

The mixture can also be applied to already-set traditional concrete to mend bigger cracks or holes.

The concrete industry is one of the most environmentally damaging in the world, accounting for 9% of total global CO2 emissions in 2018. Nearly 80% of concrete’s carbon emissions come from cement, which accounts for about 8% of the world’s carbon dioxide (CO2) emissions.

If the cement industry were a country, it would be the third-largest emitter in the world — not far behind China and the US. It contributes more CO2 than aviation fuel (2.5%) and is not far behind the global agriculture business (12%). But, overall, the construction industry, which includes not only the manufacturing of cement but also the transportation of heavy materials across the world, was responsible for a staggering 38% of all carbon emissions in 2019, according to the United Nations Environment Programme.

The enzyme-based mixture developed at the Worcester Polytechnic Institute extracts a negligible quantity of CO2. However, the mixture would offset a sizable amount of CO2 currently associated with the concrete industry by extending its life.

Rahbar makes a bold claim, predicting self-healing concrete could extend the life of a structure from 20 years, for example, to 80 years.

Scientists create bendable concrete containing CO2 to lower emissions

Unlike conventional concrete, engineered cementitious composite (ECC) can bend under pressure without rupturing. Victor Li, CC BY-ND.

Concrete is quite literally the foundation of our modern infrastructure — but it comes at a cost. The concrete industry is one of the most environmentally damaging in the world, accounting for 9% of total global CO2 emissions in 2018. Naturally, scientists are exploring other alternatives in order to offset this huge carbon footprint. One such project from the University of Michigan dramatically lowers CO2 emissions by actually injecting the greenhouse gas into the concrete, converting it into a useful mineral. The resulting concrete is also bendable, leading to less brittle structures that require fewer materials, thereby further reducing emissions.

The formula for concrete is very simple. You only have to mix aggregates — rocks and sand — along with cement and water in the proper amount. Recipes will vary depending on the type of structure (i.e. bridges versus buildings), but that’s about it.

Nearly 80% of concrete’s carbon emissions come from cement, which accounts for about 8% of the world’s carbon dioxide (CO2) emissions. If the cement industry were a country, it would be the third-largest emitter in the world — not far behind China and the US. It contributes more CO2 than aviation fuel (2.5%) and is not far behind the global agriculture business (12%).

This explains why cement is the first thing that scientists seek to optimize for lowering emissions. One approach involves using less cement in the concrete, replacing some of it with coal fly ash and iron slag. Some of the most promising results come from mixing limestone calcined clay with the aggregates, which can reduce emissions by at least 20%.

But the researchers at the University of Michigan have something even more radical in mind. Their aim is to cut the built environment’s carbon footprint in half and boost its productivity by 2030. One project in this direction is a novel composite that is engineered to react with CO2 and form minerals so that the greenhouse gas can be stored in the concrete rather than become a byproduct. What’s more, the resulting concrete seems to have a number of appealing properties.

Lab experiments showed that CO2 curing significantly improves the concrete’s strength and durability, though results can vary depending on the concrete mixes and procedures. Perhaps the most interesting property is that the resulting concrete is more bendable, allowing thinner and less brittle structures to be constructed. This would lower the requirements for reinforced steel, further reducing the carbon footprint of a construction project.

Bendable concrete is also appealing due to its enhanced earthquake resistance. The 61-story Kitahama building, the tallest residential tower in Japan, was built using bendable concrete, for instance.

These developments are important in the context of crumbling federally-managed infrastructure, as well as the COVID-19 crisis. The American Society of Civil Engineers estimates the US needs to spend some $4.5 trillion by 2025 to fix the country’s roads, bridges, dams, and other infrastructure.

Clearly, United States’ infrastructure is badly in need of an overhaul, and the economic fallout due to the pandemic may prove to be the perfect opportunity. Historically, recessions have been managed by investments in massive infrastructure projects that create a lot of jobs across multiple industries. If the Biden administration is up for this ambitious task, managing concrete emissions will prove essential in order to preserve its other objective, mitigating climate change.

Samples from this Ancient Roman pier, Portus Cosanus in Orbetello, Italy, were studied with X-rays at Berkeley Lab. Credit: J.P. Oleson.

Why Roman concrete is stronger than it ever was, while modern concrete decays

Samples from this Ancient Roman pier, Portus Cosanus in Orbetello, Italy, were studied with X-rays at Berkeley Lab. Credit: J.P. Oleson.

Samples from this Ancient Roman pier, Portus Cosanus in Orbetello, Italy, were studied with X-rays at Berkeley Lab. Credit: J.P. Oleson.

Almost 2,000 years ago, famed Roman historian Pliny the Elder wrote in his Naturalis Historia about the concrete poured in harbors that “as soon as it comes into contact with the waves of the sea and is submerged, becomes a single stone mass, impregnable to the waves and every day stronger.”

This insight is surprisingly spot on, according to a 2017 study that found seawater is the secret ingredient that makes Roman concrete extremely durable by encouraging the growth of rare minerals.

Concrete in some Roman piers is not only still viable today but stronger than it ever was, whereas modern marine concrete structures made from Portland cement crumble within decades.

The ancient Romans used concrete everywhere, particularly in their mega-structures like the Pantheon and Trajan’s Markets in Rome. They would make the concrete by first mixing volcanic ash with lime and seawater to make mortar, which is later incorporated into chunks of volcanic rock, the ‘aggregate’. The combination produces a so-called pozzolanic reaction, so named after the city of Pozzuoli in the Bay of Naples. Another common naturally reactive volcanic sand used for manufacturing concrete is called harena fossicia. It’s thought that Romans might have first gotten the idea for this mixture after observing naturally cemented volcanic ash deposits called tuff.

After the fall of the Roman empire, the recipe for making concrete was lost and a concrete of equal worth wasn’t re-invented until 1824 when an Englishman named Joseph Aspdin discovered Portland cement by burning finely ground chalk and clay in a kiln until the carbon dioxide was removed. It was named “Portland” cement because it resembled the high-quality building stones found in Portland, England.

The ancient Roman recipe is very different than the modern one for concrete, though. Most modern concrete is a mix of Portland cement — limestone, sandstone, ash, chalk, iron, and clay, among other ingredients, heated to form a glassy material that is finely ground — with so-called “aggregates.” These aggregates, usually sand or crushed stone, are not intended to chemically react because if they do, they can cause unwanted expansions in the concrete.

Outliving empires: Roman concrete

University of Utah geologist Marie Jackson’s interest in Roman concrete was sparked by a sabbatical year in Rome where she studied tuffs and volcanic ash deposits. One by one, she approached the factors that made architectural concrete in Rome so resilient. One such factor, she says, is that the mineral intergrowths between the aggregate and the mortar which prevent cracks from lengthening, while the surfaces of nonreactive aggregates in Portland cement only help cracks propagate farther.

While studying drilled cores of Roman harbor concrete, Jackson and colleagues found an exceptionally rare mineral, aluminous tobermorite (Al-tobermorite) in the marine mortar. The mineral’s presence surprised everyone because it is very difficult to make. For Al-tobermorite to form, you need very high temperature. “No one has produced tobermorite at 20 degrees Celsius,” she says. “Oh — except the Romans!”

Seeing how Jackon is a geologist, though, she immediately realized that the mineral must have appeared later. The team concluded with experiments backing them up that seawater percolated through the concrete in breakwaters and in piers, dissolving components of the volcanic ash and allowing new minerals to grow from the highly alkaline leached fluids, particularly Al-tobermorite and phillipsite, the latter being a related zeolite mineral formed in pumice particles and pores in the cementing matrix.  In rare instances, underwater volcanoes, such as the Surtsey Volcano in Iceland, produce the same minerals found in Roman concrete.

“We’re looking at a system that’s contrary to everything one would not want in cement-based concrete,” she says. “We’re looking at a system that thrives in open chemical exchange with seawater.”

The Roman concrete samples were studied using a technique called X-ray microdiffraction at UC Berkeley Lab’s ALS. The machine produces beams focused to about 1 micron or about a hundred times smaller than what can be found in a conventional laboratory.

 “We can go into the tiny natural laboratories in the concrete, map the minerals that are present, the succession of the crystals that occur, and their crystallographic properties. It’s been astounding what we’ve been able to find,” Jackson said.

This microscopic image shows the lumpy calcium-aluminum-silicate-hydrate (C-A-S-H) binder material that forms when volcanic ash, lime, and seawater mix. Platy crystals of Al-tobermorite have grown amongst the C-A-S-H cementing matrix. Credit: Marie Jackson.

This microscopic image shows the lumpy calcium-aluminum-silicate-hydrate (C-A-S-H) binder material that forms when volcanic ash, lime, and seawater mix. Platy crystals of Al-tobermorite have grown amongst the C-A-S-H cementing matrix. Credit: Marie Jackson.

The concrete industry was valued at $50 billion in 2015 in the United States alone. That year, 80 million tons of Portland cement were made or roughly the weight of about 90 Golden Gate Bridges or 12 Hoover Dams. Given the durability of Roman concrete and the substantial carbon dioxide emissions resulting from Portland cement manufacturing, why aren’t we doing it more like the Romans?

It’s not that easy at all, says Jackson. The Romans were quite fortunate to find volcanic ash in their vicinity. Also, the ingredients for their concrete recipe can’t be adapted anywhere in the world. “They observed that volcanic ash grew cements to produce the tuff. We don’t have those rocks in a lot of the world, so there would have to be substitutions made,” Jackson said.

Additionally, Roman concrete takes time to develop strength from seawater and has less compressive strength than typical Portland cement.

Nevertheless, Jackson is closely working with colleagues to make an alternative recipe based on local materials from the western U.S., including seawater from Berkeley, California. Jackson is also leading a scientific drilling project to study the production of tobermorite and other related minerals at the Surtsey volcano in Iceland.

This kind of cement could be very useful for some niche applications. For instance, the Roman cement could be employed in a tidal lagoon project meant to harness tidal power, currently planned in Swansea, United Kingdom. To recuperate the cost incurred from building it, the lagoon would have to operate for 120 years.

“You can imagine that, with the way we build now, it would be a mass of corroding steel by that time,” Jackson said.

Unless it’s made of Roman concrete.

Meanwhile, more tests are being carried out to evaluate the long-term properties of marine structures built from volcanic rock and how these fair against steel-reinforced concrete.

“I think people don’t really know how to think about a material that doesn’t have steel reinforcement,” Jackson said.

Engineers develop new impact-proof concrete made from waste

More resistant and partly done from waste, engineers at the Far Eastern Federal University (FEFU) in Russia have developed a brand-new concrete, suitable for the construction of military and civil defense structures, load-carrying structures of nuclear power plants, or even for buildings in the Arctic.

Credit Wikipedia Commons

The concrete is 40% made of waste, manufactured with rice husk cinder, limestone crushing waste, and siliceous sand. It is also 6-9 times more crackle resistant than the types produced under GOST standards, showing an improved impact endurance in initial tests.

The endurance of the new type of concrete grows with the increase of impact affecting it. According to the engineers, the construction absorbs impact due to its dynamic viscosity. This effect is caused by the reinforcement of concrete, in this case adding metal or touchstone fibers to it.

This impact-proof concrete can resist not only shell hits but also tsunami waves. Moreover, it has seismic stability. During the pouring the concrete self-seals, which means it can be used to create complex structures including underground constructions.

“Today the whole world is working on counter-terrorist security facilities that would defend other structures from a shell hit or a plane crash. We’ve approached this issue from our own angle and developed an impact-proof material. On the next stage of our work we want to create radiation-resistant concrete”, said Lieutenant-Colonel Roman Fediuk, a professor at Far Eastern Federal University.

A technological scheme for the manufacture of the new concrete has already been developed, and negotiations about its implementation are on, said Fediuk. The scheme would not require any extensive investments or modernization of facilities. The manufacture of impact-proof concrete can be even more cost-effective.

The work of the engineers is based on the principle of naturalness: they want their concrete to be as stable as natural stone. This principle is promoted by a branch of science called geonics or geomimetics. The groundwork of this field was laid by Professor Valery Lesovik from Shukhov Belgorod State Technological University.

Earlier this year FEFU engineers presented a new type of concrete with increased initial strength that would allow speeding up the concrete pouring process 3-4 times. This type of concrete doesn’t crack or leak, is resistant to low temperatures and may be used for building in the Far East and in the conditions of the Extreme North.

Hawaii explores manufacturing climate-friendly concrete

In the global construction industry, manufacturing concrete is one of the most carbon-intensive activities, mainly due to the amount of energy it needs. Hawaii is now seeking a solution through the development of a new form of concrete that reduces greenhouse gas emissions.

Credit: Wikipedia Commons

Concrete is the second most used material on the planet after water, according to the nonprofit Global Concrete and Cement Association. But its manufacturing process is far from sustainable, being among the top five sources of carbon emissions on the planet.

With that scenario in mind, Hawaii began testing an innovative building material called carbon-sequestering concrete, which has a much lower carbon footprint than conventional concrete manufacturing.

The process takes waste carbon dioxide from an industrial emitter and injects it into a concrete mix, creating a chemical reaction that turns the carbon dioxide into solid calcium carbonate. The resulting concrete mix gets incorporated with other ingredients to form the final product of carbon-infused concrete.

“As the daily baseline measurement for carbon dioxide in our atmosphere reaches the highest level in modern history, it is especially important for all of us to do all we can towards ensuring a sustainable Hawaii for future generations,” said state governor David Ige.

To test the use of this new type of concrete in road construction, the state’s Department of Transportation started a pilot program. Concrete is manufactured by Island Ready-Mix Concrete, using the technology provided by CarbonCure, which works with concrete manufacturers to install its technology in plants worldwide.

CarbonCure first brought the idea of developing its green concrete technology in Hawaii to Elemental Excelerator, a Honolulu-based startup accelerator that funds companies. Elemental Excelerator liked CarbonCure’s vision, became a supporting partner and provided funding to help broker partnerships.

CarbonCure argues concrete produced using its technology not only has a lower carbon footprint but is also stronger than conventional concrete – and just as cost-effective.

“By taking what would otherwise be pollution, a greenhouse gas, turning it into a mineral that becomes permanently embedded in the concrete, we get rid of it forever,” says Christie Gamble, senior director of Sustainability at CarbonCure. “More importantly, the mineralization process enhances the strength of the concrete, and this allows concrete producers to use less cement.”

In April, Honolulu’s City Council passed a resolution requesting that all new city infrastructure projects consider using carbon-infused concrete. Two months after Honolulu passed its resolution, an environmental commission in Austin, Texas, unanimously voted to explore the uses of carbon-infused concrete.

Astronauts mix cement in space station, pave way for buildings on other worlds

Humans have been using concrete for thousands of years to erect all sorts of buildings, from small homes to today’s skyscrapers. Concrete is very durable, strong, and cheap, which explains its widescale success — and, in the future, it might become a crucial constructions material on other words too.

A huge step in this direction was recently made by researchers working on a NASA project that mixed cement on the International Space Station (ISS).

European Space Agency astronaut Alexander Gerst works on the MICS experiment aboard the International Space Station. Credit: NASA.

As part of the experiment, called Microgravity Investigation of Cement Solidification, researchers sent tricalcium silicate, hydrated lime, and distilled water — the basic building blocks of cement — to the ISS. Once there, these ingredients were mixed and allowed to harden. The resulting structure was compared to cement mixed on Earth under normal gravity conditions.

The lack of gravity proved to play an important role in how the cement hardened. Surprisingly, the space cement has a uniform density while Earth-based cement has a more layered structure due to gravity-based sedimentation.

This uniform density makes the cement stronger. But this strength may be counter-balanced by the development of large air pockets in space cement, making it more porous than the Earth-mixed counterpart. This increased porosity makes the cement weaker.

Cement pastes mixed in space (above) and on the ground (below). The sample from space shows more porosity, which affects concrete strength. Meanwhile, crystals in the Earth sample are more segregated. Credit: Penn State Materials Characterization Lab

So, what is the net effect? That’s something that a strength test will have to determine. The researchers are planning to destroy the samples later this year after they’ve finished conducting their microstructural analysis. Ultimately, this fail test will determine which of the two types of cement is stronger.

Concrete is made by mixing two components: aggregates and paste. In the composition of modern concrete, there are various materials that are used by the industry as aggregates. These include sand, gravel, or crushed stone.  The paste is most of the time cement — a mix of limestone, clay, gypsum, and various other minerals or chemicals.

Concrete is highly attractive as a building material in space because of its good thermal and radiation insulating properties. In fact, it’s the go-to material when it comes to shielding radioactive waste.

“On missions to the Moon and Mars, humans and equipment will need to be protected from extreme temperatures and radiation, and the only way to do that is by building infrastructures on these extraterrestrial environments,” said principal investigator Aleksandra Radlinska of Pennsylvania State University. “One idea is building with a concrete-like material in space. Concrete is very sturdy and provides better protection than many materials.”

Concrete could also be mixed on off-world sites with local resources. Lunar regolith, also known as moon dust, is composed of jagged and fine dust grains that could decrease the porosity of the concrete. Radlinska and colleagues have already performed preliminary tests on lunar regolith, the results of which have been submitted for an upcoming publication.

This is why the present evaluation of microgravity-mixed cement is so important. First and foremost, it showed that it can be done.

“Even though concrete has been used for so long on Earth, we still don’t necessarily understand all the aspects of the hydration process. Now we know there are some differences between Earth- and space-based systems and we can examine those differences to see which ones are beneficial and which ones are detrimental to using this material in space,” said Radlinska. “Also, the samples were in sealed pouches, so another question is whether they would have additional complexities in an open space environment.”

Next, the researchers plan on studying various binders that are particularly suitable for various degrees of gravity, from zero gravity to Mars gravity and in between.

The findings were published in the journal Frontiers in Materials.

Concrete is responsible for a significant share of man-made greenhouse emissions. Credit: Pixabay.

Adding irradiated plastic makes for stronger concrete, cuts CO2 emissions

Concrete is responsible for a significant share of man-made greenhouse emissions. Credit: Pixabay.

Concrete is responsible for a significant share of man-made greenhouse emissions. Credit: Pixabay.

MIT undergraduate students found that recycled plastic flakes can make concrete 15 percent stronger. Discarded plastic bottles could thus one day serve a new role, inside your walls for instance, instead of polluting the environment in landfills and oceans. The plastic is first blasted with gamma rays, a process which is complately harmless.

Blasting concrete pollution

Concrete is the second most widely used construction material in the world, after water. Manufacturing and transporting concrete is responsible for 4.5 percent of all man-made carbon dioxide emissions.

While researching a student project, Carolyn Schaefer and Michael Ortega were amazed by just how many emissions the concrete industry is responsible for. If they could find a way to make concrete greener, even by a fraction, the two thought, it would be possible to lessen concrete’s strain on the environment.

“There is a huge amount of plastic that is landfilled every year,” Michael Short, an assistant professor in MIT’s Department of Nuclear Science and Engineering, told MIT News. “Our technology takes plastic out of the landfill, locks it up in concrete, and also uses less cement to make the concrete, which makes fewer carbon dioxide emissions. This has the potential to pull plastic landfill waste out of the landfill and into buildings, where it could actually help to make them stronger.”

The MIT undergrads scoured the literature and found out about previous efforts that mixed recycled plastic with Portland cement. The resulting concrete, however, was weakened. Going deeper into the rabbit hole, the two found out that exposing the plastic to gamma radiation alters the material’s crystalline structure to such a degree that the plastic turns stiffer, tougher, and stronger. So, they got the bright idea to first irradiate plastic and then mix it with cement and mineral additives (fly ash and silica fume) to manufacture a potentially stronger concrete.

The plastic in question was polyethylene terephthalate, recovered from a nearby recycling plant. The flakes were irradiated with a cobalt-60 irradiator housed in one of MIT’s basements. The irradiated flakes of plastic do not leave traces of radiation afterward so they can safely be used in cement without the fear of jeopardizing human health.

After it was poured into molds, allowed to cure, and removed from the molds, cylindrical concrete samples were subjected to a battery of compression tests. The results were then compared to those performed on concrete made from regular, non-irradiated plastic, as well as plain concrete with no plastic.

According to the MIT researchers, the presence of the gamma-ray irradiated plastic and fly ash enhanced the strength of the concrete by 15 percent, as reported in the journal Waste Management.

Using X-ray diffraction, backscattered electron microscopy, and X-ray microtomography, the researchers found that irradiated plastic, particularly at high doses, exhibited crystalline structures with more cross-linking, or molecular connections. Such crystalline structure seems to trap pores within the concrete, making it denser and stronger. Tests so far suggest that the higher the dose of gamma ray radiation, the stronger the concrete, though more work needs to be carried out to find the optimal mix of materials and radiation.

Next, Ortega and Schaefer plan on experimenting with different kinds of plastic and radiation doses. They say that replacing just 1.5 percent of concrete with plastic makes it stronger, and could have a significant impact. By one calculation, 1.5 percent plastic in concrete implies 0.0675 percent of the world’s carbon dioxide emissions would be slashed.

concrete speaker

Why a startup is making speakers out of concrete

concrete speaker

Credit: Master & Dynamic

If you’ve ever been to a party in a big concrete room, you must remember how terrible the sound was. That’s because concrete is one of the worse acoustic absorbers, it causes a lot of echo. Despite this property, some clever engineers have made speakers whose housing is made of concrete, and it reportedly sounds fantastic.

Drew Stone Briggs of newly incorporated audio company Master & Dynamic is the mastermind behind the project. He teamed up with architect David Adjaye to not only design an acoustically tuned speaker, but a sleek one to boot.

A sculpted speaker

concrete speaker

Credit: Master & Dynamic

Typically, most of the speaker’s housings or resonance chambers are made out of lightweight materials such as wood or plastic. A good speaker chamber has thick walls and internal braces that make it air tight and rigid. You really don’t want the speaker cabinet to vibrate. Ideally, you want all the speaker’s energy to push out as sound.

Concrete is great in this respect because it’s stiff. Damn stiff. By lining the interior with a soft material, the speaker is able to have very low distortion. What’s more, the engineers used a modified form of concrete which has a handful of polymers embedded inside besides the typical rock and gravel.

concrete speaker

Credit: Master & Dynamic

The tapered design acts like a horn which expands to a wide, flat surface in the front. This minimizes the area in the back of the speaker cabinet but maximizes the sound that gets pushed out. Again, it’s about managing reverberations.

“This speaker is not about the traditional idea of making boxes, but about a directional form. We created a new geometry for this speaker. A new geometry of sound,” said  Adjaye, the architect behind Washington D.C.’s new National Museum of African American History and Culture.

Overall, the damping properties of the MA770 speaker are so good you can reportedly play it at full volume without causing the table or floor to vibrate. Other features include:

  • Measurements – 410mm x 510mm x 245mm, 16kg
  • Wireless Connectivity – Dual band 802.11 a/b/g/n/ac WiFi and Bluetooth 4.1 with BLE
  • Connectivity – Chromecast built-in, Bluetooth 4.1 with BLE, 3.5mm Auxiliary Analog, TOSLINK Optical Audio
  • Streaming Services – Chromecast enabled applications including Spotify, Tidal, Pandora, Soundcloud, Deezer, and more

To make the speaker streamline, each unit is cast and cured in a mold. It’s then broken in half to create a seamless effect. The surface is shaped with a rotary tool so the speaker has a nice grainy texture.

concrete speaker

Credit: Master & Dynamic

M&D’s first speaker weighs under 40 pounds, which is pretty good for a block of concrete, albeit hollow.

You can preorder the MA770 through the Master & Dynamic website. You can test the speaker live and purchase it at the MoMA Design Store beginning on Tuesday, April 25.

Electrical concrete could de-ice by itself

An innovative type of concrete has the potential to save lives and millions off taxpayers’ money.

Credits: Chris Tuan, University of Nebraska-Lincoln

Especially in these frosty times, we all understand how troublesome snow and ice can be, especially on the road. This is where this concrete enters the stage.

The secret ingredient is a bunch of steel shavings and carbon particles that make about 20% of the entire mixture. These add-ins do nothing to weaken the concrete’s structural resistance, but they can conduct electricity, which means they can be heated.

The idea is to incorporate this type of concrete in key places, which have the highest risk of accident.

“De-icing concrete is intended for icy bridges, street intersections, interstate exit ramps, and where accidents are prone to take place,” said Dr. Chris Tuan, a professor of civil engineering at the university who designed the material.

Chris Tuan, professor of civil engineering at the University of Nebraska-Lincoln, stands on a slab of conductive concrete that can heat itself through electricity.

Of course, this would make the material much more expensive than regular concrete. A cubic yard of this material costs about $300, compared to $120 per cubic yard of regular concrete. However, in the long run, this might actually save money, because de-icing chemicals are hugely expensive themselves. Furthermore, salt, which is most commonly used in de-icing erodes concrete, can cause holes, rusts cars and has a significant detrimental effect on both the plants and the animals in the area. All these sum up at several billion dollars per year.

There’s also another hidden advantage – if we electrify parts of roads, then it could become much easier to power up electric vehicles. Also, by replacing the limestone and sand typically used in concrete with a mineral called magnetite, Tuan has shown that the mixture can also shield against electromagnetic waves, protecting against unwanted intrusions.

“We invite parties that are interested in the technology to go in there and try to use their cell phones,” said Tuan, who has patented his design through NUtech Ventures. “And they always receive a no-service message.”

But the main idea remains reducing the risk of accidents and saving lives. According to the US Road Weather Management Program, there were over 500,000 crashes in the past 10 years caused by snowy or frozen concrete, resulting in 2000 fatalities. This means that 200 lives a year could be saved with this pavement.

The technology itself is not new; electrified concrete has been used on a 150-foot bridge near Lincoln, Nebraska. The bridge was inlaid with 52 slabs of de-icing concrete in 2002 and has successfully defrosted itself ever since, without the need for further chemicals. Now, Tuan wants to convince airports to use it, and for good reason.

“To my surprise, they don’t want to use it for the runways,” Tuan said in a statement. “What they need is the tarmac around the gated areas cleared, because they have so many carts to unload — luggage service, food service, trash service, fuel service — that all need to get into those areas … They said that if we can heat that kind of tarmac, then there would be (far fewer) weather-related delays.”

In the meantime, he’s enjoying the benefits of this technology himself.

“I have a patio in my backyard that is made of conductive concrete,” he said with a laugh. “So I’m practicing what I preach.”

concrete parking garage

What is concrete: how concrete is made and why it’s so important

Concrete practically surrounds us, but how many of us really know what it is? Almost every building project on the planet uses concrete at some point in the process: footings and foundations for homes, office buildings, and highway projects, as well as sidewalks, architectural elements, dams, and skyscrapers. From bridges to swimming pools to highways, concrete has probably been used to construct it. It’s versatile, relatively inexpensive, and it endures under punishing conditions.

 

concrete parking garage

Concrete is the foundation material to mankind’s buildings, streets, and cities going back to Roman times. Yet, it’s not something the average non-construction worker can tell you about without a quick trip to their computer keyboard. So to solve the mystery of today’s concrete, we’ve got to look at its history and its origins.

First of all, the term concrete does not define a specific material—more a mix of them. Cement and broken stone or gravel is mixed with water to form concrete. Basically, a mix of paste and rock that hardens. The magic behind concrete’s great history and vast array of uses comes from its multitude of uses; concrete, as well as cement (think of it as a kind of glue), can be shaped and molded while wet but is incredibly hard, strong and durable after it dries.

The history of concrete 

Concrete as a building material is thought to have been used as early as 6500 B.C., beginning in what is now known as Syria and Jordan. Ancient structures, many of which are still standing today, have been identified by most Scholars as being constructed from some form of concrete. The process of mixing sand, gravel, limestone, and water for building materials was used, in one form or another, throughout the ancient world for thousands of years. Babylonians and Assyrians used clay as the mortar or ‘glue’ to keep their rock, gravel, and sand mixtures in place. But it was not until the rise of the Roman Empire that concrete was able to ‘hold its own,’ as it were. The discovery of an ancient form of cement is what first changed the nature of what we now call concrete.

The metamorphosis of a pliable substance into one that a civilization could be built upon is what first fascinated the Romans in the early 1st Century. The Parthenon and the Colosseum were both constructed using Roman concrete and are still partially standing to this day. But Roman engineers did not merely improve upon the ancient mixture—sometimes called ‘Liquid Stone’—they created what would become the most widely used man-made building material in the modern world.

The Romans found magic in a volcano known as Campi Flegrei, near the town of Pozzuoli, Italy. Specifically, a magic volcanic dust that turned to stone when it touched water. This ‘magic’ dust was known as ‘Pozzolana’ and was a construction miracle for the Roman world.

As it turns out, Pozzolana—Italian volcanic ash—is the perfect mixture of silica oxides and lime, which, when mixed with water is the basis for what we now call cement. It has been speculated that ancient Roman engineers observed the hardening of volcanic materials when it entered the sea and wondered if the process could be re-created in the building process. As a result, concrete and the Roman building boom was born.

The weight-bearing abilities and pure durability of concrete made it the material of choice for many ancient builders, who used it to construct baths, piers, and harbors for the Romans. However, when the Roman Empire fell in the 5th Century A.D., knowledge of concrete fell with it. Concrete making was lost to history for more than a thousand years—out of use and out of mind until the 19th Century. An Englishman named Joseph Aspdin rediscovered concrete and patented it as Portland Cement in 1824. Mr. Aspdin’s patented cement still makes up the majority of what we call grout, mortar, and stucco in today’s buildings.

How concrete is made

how concrete is made

Making concrete isn’t that different from one of children’s favorite pastimes: making stuff out of mud using molds, then left to dry in the sun. No skyscrapper ever could be made out of mud, of course, so there must be more to it.

Essentially, concrete is made by mixing two essential components: aggregates and paste. In the composition of modern concrete, there are various materials that are used by the industry as aggregates. These include sand, gravel or crushed stone. The particle size of the aggregates can matter a lot, depending on the type of construction. Fine aggregate is considered anything with particles smaller than 0.2 inches (5 millimeters), while coarse aggregates can be as large as 1.5 inches (38 millimeters).

The paste is most of the time cement — a mix of limestone, clay, gypsum and various other minerals or chemicals.

Aggregates and paste need to mixed in the right proportion if we’re to make strong and durable concrete. If you don’t put enough paste, then the concrete will have too many voids between aggregates (porous concrete and rough surface). Excess cement will always produce a nice, smooth surface but this can crack more easily and can become costly.

After the material have been appropriately proportioned, water is added in the right amount. The water-cement ratio is the weight of the mixing water divided by the weight of the cement. A chemical process called hydration is initiated. During this reaction, each cement particle forms a node that grows, linking up with other cement particles or adhering to nearby aggregates.

When the resulting mixture dries, it forms a solid stonelike mass. The best concrete has a low water-cement ratio. Engineers play with this ratio until they reach a soft spot between quality and fresh concrete workability.

Typically, the industry uses a mix that looks like this: cement (10 to 15 percent), aggregate (60 to 75 percent) and water (15 to 20 percent). Air is an inevitable component of concrete and makes-up 5 to 8 percent.

Rediscovering concrete

The main ingredients in Portland cement—the literal mortar of the modern world—are calcium silicates, formed when limestone and clay are mixed and heated to over 1,000 degrees Fahrenheit. Chemically, roughly the same formula that created ‘Pozzolana’ inside the Campi Flegrei volcano centuries before.

The trick is in remembering that cement is not the same as concrete. In the many years since 1824, the construction industry has tweaked, improved, and expanded the formula for making concrete with a mountain of additives and processes, but cement is still the glue that holds everything together.

Today’s concrete, with cement as one of its main components, is able to support huge amounts of weight without crumbling. It has compressive strength. Concrete is limited however, when it comes to tensile strength—the ability to bend. Concrete breaks when it bends. That’s a big problem when building bridges, dams or support columns that must make constant adjustments for weather and wear to endure.

The tensile strength of concrete has been enhanced since Roman times with additions to the chemical mix. In 1849, just twenty-five years after the patenting of Portland Cement, Joseph Monier, a Parisian pot-maker, invented reinforced concrete. Monier received a patent for his method of adding steel bars or mesh to concrete before it hardens, which brought about yet another innovation in modern building techniques and improved the tensile strength of concrete. Reinforced Concrete is still widely used today in a multitude of projects, from skyscrapers, dams, war memorials, bridges, and highways.

The future of concrete

Traditional concrete can absorb only 300 millimeters of water an hour. In contrast, Topmix can safely due away 36,000 millimeters of water an hour.

Now that you know what concrete is, you should also know what it’s in the process of becoming. Many new forms of the ancient mixture are being developed and increasingly used in construction today. One of most exciting improvements to concrete in recent years is the development of pervious concrete.

Also known as porous pavement, pervious concrete holds qualities opposite to traditional concrete in that its particles are so large they allow water to seep all the way through them. Rather than repelling water and causing urban flooding after a rain like impervious concrete does, pervious concrete allows natural run-off and ground absorption of the water. Together with the promise of driverless cars, pervious concrete could bring about significant changes to driving conditions in the near future. Also, self-repairing concrete is definitely something to watch.

No matter what you call it, though, the world as we know it would not exist without the discovery and use of concrete. It’s in our buildings, our cities, and our highways. It’s the very bedrock of our civilization and is contained in most everything we look at, live and work in, and drive on.

topmix concrete

Your eyes aren’t fooling you – this concrete absorbs 1,000 gallons of water per minute

topmix concrete

When there’s rain, let alone a storm, city streets form puddles and in some extreme cases get flooded. That’s because concrete mostly keeps water out, and only a tiny volume gets absorbed. A company from the UK, however, has come up with such an innovative solution that it almost seems like magic were it not pure science at work. Namely, they came up with a new kind of concrete that allows more water to percolate through its gaps, so much that  1,056 gallons were gobbled up in under 60 seconds during a test. It all seems unreal – but it’s as concrete as it gets.

Pavements that allow water to creep through aren’t exactly new. For decades various universities and private companies demonstrated permeable pavements and deployed these in pedestrian areas. The Topmix Permeable material stands out, however, since it’s a type of concrete and hence supports more weight.

[LEARN] What exactly is concrete?

A closeup of the permeable concrete. Credit: imgur user showmm.

A closeup of the permeable concrete. Credit: imgur user showmm.

Traditional concrete can absorb only 300 millimeters of water an hour. In contrast, Topmix can safely due away 36,000 millimeters of water an hour. The company behind the material,  Tarmac, says this is possible because their concrete is more porous seeing how crushed granite replaced fine sand which typically blocks the water. Once past the concrete, the water can either percolate straight into the ground which naturally has a high absorption potential or it can wind up in sewers or the stormwater drainage. Alternatively, the water can be collected in a special container for later use in flushing toilets or irrigation. It all depends on what a municipality needs.

As climate change intensifies and storms become more frequent, so will the sight of flooded streets. Most cities in the United States are in desperate need of an overhaul seeing how their stormwater drainage systems are old, leaky and out of phase with current needs. Topmix might be part of the mix of solutions that municipalities might employ to keep their cities in order.

[MORE] Self-repairing concrete might build the world

At the moment, Topmix is available for sale only in the UK. Tests ran by Tarmac suggest, however, that Topmix isn’t suitable for busy streets. It’s optimal for traffic 30 miles per hour or less and the concrete doesn’t fair too well in the cold. Less busy streets and parking lots seem like a great fit though and, who knows, a future refined version might be able to hold more weight. Either way, who knew concrete could be this thirsty?

Self-repairing concrete might build the future

Tomorrow’s bridges, tunnels and other engineering structures might be built with a different material – a type of “smart” concrete. Belgian researchers at the University of Ghent have created two types of self-repairing concrete, using polymers and bacteria.

Image via Flickr.

 

“The concrete is filled with super-absorbent polymers. So when a crack appears, water comes in, and the super-absorbent polymers swell and they block the crack from further intake of water.”

The concrete was developed as part of a pioneering European project called healCON. The idea of developing self-repairing materials is not new, and it has been suggested in several materials, though it hasn’t been applied at a truly large scale. Bath University researchers have also suggested using self-repairing concrete last year, and the topic seems to be picking on a lot of steam.

Nele de Belie, Technical Director of the Magnel Laboratory for Concrete Research explains that impermeability is the key factor:

“You do not have healed concrete regain its strength completely. It’s strong enough as it is. What you do want to regain is the liquid tightness and impermeability, so that durability still remains fine”.

Basically, special polymers are added into the cement mix, and make it so that small cracks are healed. As scientists explain, small cracks aren’t a big problem in itself – it’s the fact that they tend to grow into bigger cracks.

“If a small crack starts healing immediately, then there is no risk that it grows bigger. So the total structure won’t run the risk of falling down. We want to stop the problem before it is big enough”.

In order to design the polymers, the team took inspiration from nature. Biological systems such as bones, skin or plants have the capacity to detect damage very quickly and repair it – they wanted to do the same for concrete. Needless to say, the potential of such a self-healing concrete are huge, in terms of stability and reducing maintenance and repair costs.

Image credits: healCON.

 

They also tried another approach – one which used a more organic approach to self-healing concrete – namely bacteria.

“These are bacteria that we have isolated from locations in our planet that have conditions which are similar to concrete,” says Henk Jonkers, a biologist at Delft University of Technology. “One condition is rock-like. The other condition is being very alkaline, so very high PH conditions. These bacteria like to grow under those conditions. These bacteria are not pathogenic, and are not harmful for human beings or for the environment”.

According to reports, both approaches passed initial lab tests. For example, with the bacteria solution, as soon as cracks appear, the bacteria starts to produce calcium carbonate and fill them up. It’s not clear at the moment exactly how impenetrable this filling is though. The next steps are to test the technology in big-scale real life conditions, test the impenetrability, and ultimately conduct a life-cycle assessment to see just how much money and effort it can save.

“The initial cost will increase. But then if you can reduce the maintenance costs and you increase the service life of the structures, then at the end, this self-healing concrete presents an economically positive picture”.

You can find out more about this project from their webpage, where you can also browse their publications.

 

 

Building houses with bacteria

Houses of the future might be built with bacteria – at least partially. It may sound like science fiction, but a Spanish company located in Madrid is working to make that a concrete reality.

Image via Eco-Cement.

It all starts with a common type of soil bacterium being. Put it in some soil, provide it with nutrients, and keep the temperature steady at about 30 degrees, and then let it work its magic; after a while, add it to a mix of sand, industrial cement waste and the ash of rice husks.. Piero Tiano, a biologist with the Italian Institute for the Conservation and Preservation of Cultural Heritage told euronews how it works:

“Inside this mix, bacteria starts to develop; they basically grow in number. The bacteria has to reach a certain quantity in order to make cement. After around three hours of fermentation, our mix is ready for use”.


OK, but why would they want to do this? Well, about 5% of global carbon emissions originate from the manufacturing of cement. Furthermore, the global production of cement in 2030 is projected to grow to a level roughly 5 times higher than its level in 1990, with close to 5 billion tones worldwide This project aims to make cement not only cheaper and easier to make, but also more sustainable.

“Our raw materials are basically all waste. So we don’t have added costs,” said Laura Sánchez Alonso, a mining Engineer and Eco-Cement project coordinator. For instance, we don’t need to extract and transport the limestone commonly used to produce cement. And we also save the energy costs”

Less heat means lower amounts of energy invested and less emissions. To put some figures down, this technology can reduce greenhouse gas emissions by 11%, and production costs by 27%. This might not seem like much, but again – consider the massive quantities of cement fabricated throughout the world. This are also only the initial results – researchers are working to make the technology even more efficient and eco-friendly.

“In ordinary cement, they have to use very high temperatures, up to 1,400-1,500 degrees Celsius in order to turn limestone into cement. That is part of the process. And that takes an awful lot of energy. Here we only need bacteria to multiply at 30 degrees. So that is a massive difference. And that amount of heat energy is saved because we are using a biological process to bind the particles together”.

The bacteria basically produces limestone, but if it’s not carefully planned, it may produce too much or too little.

“It’s important to know the ideal density of bacteria in the mix,” said Linda Wittig, an industrial chemist with Fraunhofer-IFAM.

To make things even more interesting, the resilience, resistance and sturdiness of the resulting structure means that researchers can also use this bacteria to create mortar.

“We decided to use this material as mortar and not as concrete because it is not as strong as traditional concrete. But it can be easily transformed. This is the reason why we decided to use this material as mortar,” said Nikos Bakas, a civil engineer at Neapolis University in Greece.

Realistically speaking, the technology is still a few years away before actually hitting the shelves – but developing a cheaper, easier and more sustainable system of creating cement… sign me up any day!

Green Garage Can Be Done

Why you should build an eco-friendly garage

Green Garage Can Be Done

Green Garage Can Be Done

More and more people are becoming aware of the harmful effect that human activity is having on the environment, and are attempting to reduce the impact by making alterations to their lifestyle and homes. The concept of energy saving ‘eco garages’ is also becoming increasingly popular, not only do they conserve energy but also save money. You can build large concrete garages that will shelter your pride and joy cars but also get on the green band wagon.

Concrete Can Be Cheap and Eco

Green Concrete Being Laid

Green Concrete Being Laid

Some may already have concrete garages, which is a great start. Concrete is an incredibly cheap and sustainable material. Pervious concrete allows water to drain back into the ground on which it is laid when it rains. In terms of using it for roofing, it is waterproofed using Hydrophobic Pore-Blocking Ingredients (HPI’s), to repel water and blocks out dampness and leaks and is extremely hardy, therefore cutting down on future repair costs. Green concrete offers a variety of cost effective options for building an environmentally friendly garage.

The Door

Of course you’ll also need a garage door. There is a range of recycled and recyclable materials available in all colours and styles so there is no need to compromise on the appearance of the garage. They are weather resistant and designed to effectively insulate the building to prevent heat loss. This is particularly useful if the garage is attached to the home and saves not only energy but unnecessary extra cost to the owner. To add to this, you could provide power to the garage by installing solar panels in the roof.

Electric Car Charging Point

Teslar Charging

Teslar Charging

The ultimate eco-garage would obviously house an electric car and domestic charging point for the vehicle.

It is thought that by the year 2020, ten per cent of vehicles purchased will be electric cars.  With the commencement of various schemes across  the UK, not only are charging points being installed  in public places such as supermarkets and car parks, but people are now being encouraged to have them fitted domestically.

UK Energy Saving Trust

UK Energy Saving Trus

UK Energy Saving Trus

In Scotland, The Energy Saving Trust are offering grants to residents to install a completely free 32 amp domestic charging point, with all installation costs covered as well, and with numbers of electric car sales estimated to increase this year in the UK, similar schemes will be offered elsewhere. So why does it make sense to have a charging point at home?

Well, for a lot of people that return home for the evening night, their electric vehicle can be charging whilst they sleep. Off peak electricity is far cheaper and with no fuel costs to pay this means the running of the car will be extremely cheap. Not only is this beneficial to the owner, but will do wonders for reducing carbon emissions. If you consider the predictions that there could be 700,000 solar powered homes by 2020, this will mean extremely good news for the environment. In New York, there’s actually a pilot program which allows electric cars to recharge when parked using wireless induction via charging docks that look like manholes.

 

Berkeley develops new, earth-friendly way to create concrete – inspired from the Romans

In a quest to make concrete not only more durable but also more sustainable, a group of geologists and engineers have found inspiration in the ancient Romans – whose imposing buildings have passed the test of time, surviving two millennia.

Geology and the Romans

Chris Brandon of the ROMACONS project collects a sample of ancient Roman concrete drilled from a breakwater in Pozzuoli Bay, near Naples, Italy.

Chris Brandon of the ROMACONS project collects a sample of ancient Roman concrete drilled from a breakwater in Pozzuoli Bay, near Naples, Italy.

Using classic microscopy, as well as the Advanced Light Source at Lawrence Berkeley National Laboratory (Berkeley Lab), a synchrotron light source, one of the world’s brightest sources of ultraviolet and soft x-ray beams, the team examined the fine scale structure of Roman concrete. They have described, for the first time, how the extraordinarily stable compound – calcium-aluminum-silicate-hydrate (C-A-S-H) – binds the material used to build the sturdy constructions.

Their work could improve the quality and sustainability of concrete, particularly in ocean environments. Modern concrete starts showing significant signs of degradation after approximately 50 years (quite often sooner). The method also leaves behind a smaller carbon footprint than the common counterpart.

Portland vs the Romans

croman concrete 2Portland cement (often referred to as OPC, from Ordinary Portland Cement) is the most common type of cement in general use around the world. The process for creating Portland cement requires fossil fuels to burn calcium carbonate (limestone) and clays at about 1,450 degrees Celsius (2,642 degrees Fahrenheit); about 7% of all CO2 emissions each year come from this activity. The production of lime for Roman concrete, however, is much cleaner – requiring about 1.000 degrees Celsius to be created (2/3 of its counterpart).

“Roman concrete has remained coherent and well-consolidated for 2,000 years in aggressive maritime environments,” said Marie Jackson, lead author of both papers. “It is one of the most durable construction materials on the planet, and that was no accident. Shipping was the lifeline of political, economic and military stability for the Roman Empire, so constructing harbors that would last was critical.”

Marie Jackson holds a 2,000-year-old sample of maritime concrete from the first century B.C. Santa Liberata harbor site in Tuscany.

Marie Jackson holds a 2,000-year-old sample of maritime concrete from the first century B.C. Santa Liberata harbor site in Tuscany.

The Roman Empire, arguably the most important Empire in all history, left behind numerous stunning constructions. Concrete was their material of choice, and the process was described around 30 B.C. by Marcus Vitruvius Pollio, an engineer for Octavian, who became Emperor Augustus. The key ingredient, which is not really a secret, is volcanic ash – which the Romans combined with lime to form mortar. They packed this mortar and rock chunks into wooden molds which they then immersed in seawater – harnessing the salt and water as important parts. This also led to the development of a very rare hydrothermal mineral called aluminum tobermorite (Al-tobermorite).

“Our study provided the first experimental determination of the mechanical properties of the mineral,” said Jackson.

A modern solution

So if their method was so good, why did it decline then?

“As the Roman Empire declined, and shipping declined, the need for the seawater concrete declined,” said Jackson. “You could also argue that the original structures were built so well that, once they were in place, they didn’t need to be replaced.”

While Roman concrete is incredibly durable compared to what we use today, it is pretty much impossible to use it nowadays; why? Because it takes too long to dry, and you can’t apply it in constructions where fast hardening is necessary.

But researchers are now finding ways to apply their findings on Roman concrete. Fly ash, one of the residues generated in combustion, is commonly used in the fabrication of concrete, and now, they are trying to prove that you can use volcanic ash instead of it – like the Romans did.

“There is not enough fly ash in this world to replace half of the Portland cement being used,” said Monteiro. “Many countries don’t have fly ash, so the idea is to find alternative, local materials that will work, including the kind of volcanic ash that Romans used. Using these alternatives could replace 40 percent of the world’s demand for Portland cement.”

They are trying to take the best of the 2 cements, and mix it together.

The research was published in the Journal of the American Ceramic Society

Via Berkeley