Australian Engineers Use Polymer Rebar to Reinforce Concrete

RebarDid you know that modern concrete bridges require maintenance about once every five years, and major rehabilitation every 20 years? That’s true now, but a new type of rebar could change that in the future.

A team of engineers at Deakin University in Victoria, Australia has developed an experimental polymer rebar to reinforce concrete and improve its lifespan.

Steel rebar is typically embedded within concrete structures to give them support. However, the rebar rusts over time, and eventually the rust takes up more space than the original rebar. Rusted steel begins to push against the surrounding concrete, leading to an issue called spalling, where the concrete cracks and falls away from the main structure, thereby weakening it.

The Australian team, led by Dr. Mahbube Subhani and Dr. Kazem Ghabraie, developed a non-rusting rebar made of glass fiber-reinforced polymer and carbon. According to the engineers, the new type of rebar is stronger than steel rebar at just one-fifth of its weight.

The new rebar is also more environmentally friendly, since it requires only a quarter as much energy to manufacture.

In the Australian city of Geelong, the polymer rebar will soon be used in the construction of a pedestrian bridge. According to the Deakin University researchers, the bridge will not require any maintenance during its planned century-long lifespan. The bridge will also use eco-friendly concrete that is made using fly ash from coal combustion. Traditional cement production is a significant source of man-made carbon dioxide emissions.

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Hawaii DOT Tests New Carbon-Injected Concrete Mix

Concrete PavingIn an effort to reduce the carbon footprint of road construction, the Hawaii Department of Transportation (HDOT) is testing a new carbon-injected concrete mix.

To test the mix, HDOT will pour about 4000 cubic feet of the carbon-injected concrete mix next to the same amount of standard concrete mix. The test will take place on an access road for the second phase of the Kapolei Interchange.

By comparing the two mixes side by side, HDOT will be able to establish specifications for the use of carbon-injected concrete in future road projects.

The carbon-injected concrete mix is made by Island Ready-Mix Concrete. The company mixes waste carbon dioxide from Hawaii Gas into the concrete using CarbonCure technology. This process traps the carbon dioxide in mineral form within the concrete, enhancing the material’s overall strength.

According to HDOT, the quantity of concrete poured in the demonstration will save about 1500 pounds of carbon dioxide. The demonstration alone will offset the carbon dioxide emissions of approximately 1600 miles of highway driving. If the carbon-injected concrete mix is more widely used, the environmental impact will be even greater.

Elemental Excelerator, a Hawaii-based startup accelerator, is supporting the project. Aki Marceau, managing director of Elemental Excelerator, says: “We are proud that Hawaii is looking at sustainable building practices to mitigate the effects of climate change.”

Hawaii Governor David Ige is glad to see his state taking the lead on sustainable road construction as well.

“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 Ige in a recent statement.

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MIT Designers Create Huge Concrete Blocks That Can Be Assembled by Hand

StonehengeVisit just about any construction site today and you’ll see cranes hoisting large slabs of concrete into place. However, cranes haven’t always been around, and for thousands of years human beings moved large stones by hand.

Matter Design, a Boston-based company directed by MIT professor Brandon Clifford, recently collaborated with the multinational building materials company Cemex to explore ancient methods of moving heavy stones, while developing a brand-new way to move concrete slabs by human hands alone.

Matter Design studied how ancient architecture was built, analyzing Stonehenge and the archeological sites of Easter Island. They then developed a project called Walking Assembly, a set of interlocking concrete puzzle pieces that can be assembled into a solid wall and staircase in just 15 minutes.

Each piece is 5 feet tall and weighs between 926 and 1,543 pounds. The designers also used to different densities of concrete in the blocks. While they’re definitely too heavy for a human being to lift, they can be “walked” into place. Cleverly applying their knowledge of physics, the designers manipulated each block’s center of mass so that the blocks naturally move along their curved bottoms. Assembling the pieces requires very little human energy, since gravity and the pieces’ varying densities do most of the work.

Walking Assembly has real-world applications. Imagine if, instead of having to demolish concrete structures, they could be easily disassembled and reconstructed, with no expensive equipment or landfills required. The project could ultimately help engineers find cheaper, easier ways to build complex structures.

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How to Keep Weeds From Growing in a Concrete Paver Patio

Weed Growing in PatioAre unsightly weeds taking a toll on the appearance of your concrete paver patio? These weeds might be awfully stubborn, but there are steps you can take to prevent unwanted growth from sprouting in the joints of your paver patio. This way, your patio will always look as good as the day it was first built.

Begin by killing any existing weeds.

The first thing you’ll want to do is kill any existing weeds that are already growing in your patio. There are many products you can buy to do this, but the safest way to kill weeds is with a solution of white vinegar, water and a few drops of dish soap. Just apply this solution to the weeds with a spray bottle and they should begin to die in a matter of hours.

Manually remove the remaining weeds

Once the weeds have died, you should remove them by hand to prevent them from growing back. If possible, use a short-handled weeding tool to pull the weeds up by their roots; simply breaking weeds off at the base of the stem may not be enough to keep them from returning in the future.

Fill the joints between concrete pavers with polymeric sand.

Now that you’ve removed the existing weeds from your patio, it’s time to fill the joints between the concrete pavers so that weeds can’t come back. Specifically, you should use polymeric sand that contains a special bonding agent that forms a tight seal when wet. Use a broom to work the sand into the joints, wet it with a misting attachment on a garden hose and then allow it to dry for a few days to create a tight, weed-proof seal.

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Old Tires Could Help Prevent Fire Spalling in Concrete Structures

Used TiresWhen a concrete structure or paved surface is involved in a fire, it won’t burn. It may, however, “spall.” When this happens, the outer layers of concrete will break apart violently and leave the structure unstable. In some cases, an entire structure may collapse to the ground as a result of intense fire spalling. The good news is, there might be something that concrete installers can do to prevent this from happening in the future.

Recently, a few companies have started adding polypropylene fibers to concrete when it’s being poured to stop it from spalling.

These fibers create small channels inside the concrete that allow moisture to escape, thereby preventing the explosive spalling that can take place during a fire. Unfortunately, though, pure polypropylene fibers are quite expensive to produce.

That’s why a team of researchers at the University of Sheffield in England is experimenting with ways to extract polypropylene fibers from the rubber found in recycled tires. If they’re able to develop a cost-effective way to extract the fibers and distribute them evenly in poured concrete, it could make the concrete structures of tomorrow far better able to withstand fire damage.

There’s still more work that needs to be done before we can start using our recycled tires in concrete construction, but it might just be a matter of time before this innovation becomes a practical reality. Until then, you can count on Bergen Mobile Concrete to provide you with the concrete delivery services you need to build durable patios, porches and more on your property. To get started, feel free to give us a call at (201) 797-7550 today!

Texas Company Receives Permit to Build 3D-Printed Concrete Homes

Concrete Home Over the course of the past few years, there has been a lot of buzz surrounding the idea of 3D-printing homes and other structures. 3D-printed homes have the potential to be affordable, durable and sustainable—a combination that is appealing both to home builders and prospective homeowners. But until recently, most companies pursing 3D-printed construction have only been able to show off rough demos of the process. This has left some skeptics to wonder if 3D-printed homes are ever actually going to get off the ground.

That could be about to change, however, thanks to an Austin, Texas-based company called Sunconomy.

Sunconomy recently partnered with a San Francisco-based housing development company called Forge New to begin leasing and licensing a 3D-printed home system called We Print Houses to home builders and residential contractors across the U.S. This system features both a mobile platform and mechanical systems that will provide builders and contractors an opportunity to create 3D-printed concrete homes.

Sunconomy says there will be a number of notable benefits associated with using their technology to 3D-print homes.

To begin with, the company claims it will only take a few weeks to build concrete homes using their system. The homes are also reportedly quite energy efficient and able to withstand everything from hurricane-force winds and hail to flooding and even earthquakes. In addition to giving builders and contractors a chance to employ the We Print Houses system in real-world scenarios, Sunconomy is also offering training courses and a certification program to help their customers make the most of the technology.

It remains to be seen whether or not the We Print Houses system is the game-changer Sunconomy hopes it will be, but it’s already being used to build at least one 3D-printed concrete home in Texas. Sunconomy calls the home “Genesis,” and it will feature three bedrooms, two bathrooms, a garage and its own renewable energy generation system at a cost of just under $300,000.

3D-printed concrete structures may not be in the mainstream just yet, but with companies like Sunconomy leading the way, they could be one step closer to widespread adoption.

Concrete Overlays Are Extending the Life of America’s Roads

Concrete TruckDoes it seem like road crews are resurfacing the highways in your area with fresh asphalt practically every year? This is due to the fact that asphalt roads, for all their virtues, have fairly limited lifespans, particularly in regions that experience harsh winter weather.

Thanks to recent innovations in the paving industry, however, some contractors are now using thin layers of concrete to extend the lifespan of roadways by as much as two decades.

In recent years, unbonded concrete overlays—which are typically less than six inches thick and separated from existing roadways by an even thinner layer of nonwoven polypropylene fabric—have been used to rehabilitate damaged roads in a number of states including Iowa, Minnesota, North Carolina and California. According to the American Concrete Pavement Association (ACPA), concrete overlays currently account for about 12.5 percent of the total volume of concrete pavement that’s poured in the U.S. each year.

By using existing roadways as a base layer for support, unbonded concrete overlays offer a cost-effective, long-term alternative to full-depth paving work and asphalt resurfacing.

“you add more structure with a concrete overlay than an asphalt overlay just by nature of the materials being stronger,” said ACPA President and CEO Gerald Voigt in a recent interview with Equipment World. “They last longer; they’re stronger inch by inch … From a user impact standpoint, you’re getting 20-plus years out of a concrete overlay versus an asphalt overlay getting eight, nine, maybe 10 years.”

Keep an eye out—before too long you may see these concrete overlays being used to rehabilitate a damaged roadway near you.

Scientists are Working to Develop Carbon Neutral Concrete

Carbon EmissionsConcrete might form the bedrock of modern urban construction, but its impact on the environment is raising concerns among climate researchers. Recent estimates suggest that Portland cement, the essential binding ingredient in concrete, accounts for roughly seven percent of global carbon emissions.

That could change soon, however, thanks to a multinational effort to drastically reduce the carbon output of the cement manufacturing process.

In Switzerland, for example, a group of scientists recently published a study that found it would be possible to reduce carbon emissions from the concrete sector by 80 percent without using carbon capture technology. These scientists argue that by optimizing concrete mixes, increasing the use of alternative fuels and recycling raw materials to produce the active ingredient clinker in cement, the concrete industry could effectively slash its carbon emissions by 2050.

Meanwhile, in Lithuania, another group of scientists is replacing Portland cement with alkali-activated industrial waste products such as fly ash to make concrete production more environmentally friendly as well. Although their carbon-cutting concrete is still in development, it is reportedly just as strong as conventional concrete and better able to resist damage from temperature fluctuations and exposure to acids.

Here in the United States, researchers at UCLA are also exploring innovative new ways to capture and repurpose carbon emissions from the cement manufacturing process. By creating a closed system wherein carbon dioxide is captured and recombined with calcium hydroxide to create limestone, they hope to make cement production a completely carbon-neutral process.

Thanks to the efforts of researchers all of the world, the concrete of the future may not only be stronger and more durable, but better for the environment as well.

In India, Waste Plastic Could Begin Replacing Sand in Concrete

Plastic BottlesIndia’s urban populations are growing at an unprecedented rate, and construction crews are having trouble keeping up with the demand for structural concrete due to a nationwide sand shortage. Meanwhile, the country’s lack of recycling infrastructure is allowing thousands of tons of waste plastic to pile up in city streets as well. But thanks to a joint effort between researchers at the University of Bath in the UK and Goa Engineering College in India, a new type of sustainable concrete could soon help to alleviate both these issues.

These researchers found that by replacing 10 percent of the sand in a conventional concrete mixture with waste plastic particles from ground up bottles, they could create a viable, eco-friendly construction material. If their plastic-infused concrete is widely adopted by India’s construction industry, the researchers estimate it could save 820 million metric tons of sand each year.

“The key challenge her was to have a limit between a small reduction in strengths, which we achieved, and using an appropriate amount of plastic to make it worthwhile,” said Principle Investigator Dr. John Orr in a statement. “It is really a viable material for use in some areas of construction that might help us to tackle issues of not being able to recycle the plastic and meeting a demand for sand.”

Although this concrete was specifically designed to help meet the unique needs of India’s construction industry, it could be useful in other regions with limited recycling capabilities as well.

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Engineer Develops New Sealant That Could Prevent Concrete Cracks

HighwayThe nation’s concrete roadways receive a whole lot of wear and tear, particularly in regions that experience extreme changes in temperature during the summer and winter. These temperature fluctuations can cause paved concrete surfaces to expand and contract, resulting in cracks that require seasonal repairs and replacement.

Thanks to the efforts of a mechanical engineering professor at Louisiana State University, however, transportation officials could soon be able to treat concrete roadways with a polymer-based sealant that mitigates the effects of seasonal expansion and contraction to prevent cracking. This, in turn, could save states a great deal of money in repairs each year.

Engineering professor Guogiang Li first began experimenting with polymer-based sealants in 2009, after receiving funding from the National Cooperative Highway Research Program and the Louisiana Research Transportation Center. His first prototype was a one-way memory shape polymer that could stretch and compress in response to seasonal temperature fluctuations. Then, in 2012, he created an improved two-way shape memory polymer sealant and combined it with asphalt to improve its ability to bond with concrete and resist environmental wear.

Following a successful round of laboratory testing, transportation departments in Louisiana, Texas and Minnesota will begin testing the concrete sealant’s performance on real roadways this year. This testing and certification process is expected to be complete by the end of 2019. If it performs as advertised, the polymer-based sealant could become a common feature of concrete roadways throughout the country.

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