Tech
Cardboard and earth combine to create low-carbon alternative to concrete
Engineers in Australia have developed a new building material with about one quarter of concrete’s carbon footprint, while reducing waste going to landfill. The research is published in the journal Structures.
This innovative material, called cardboard-confined rammed earth, is composed entirely of cardboard, water and soil—making it reusable and recyclable.
In Australia alone, more than 2.2 million tons of cardboard and paper are sent to landfill each year. Meanwhile, cement and concrete production account for about 8% of annual global emissions.
Cardboard has previously been used in temporary structures and disaster shelters, such as Shigeru Ban’s iconic Cardboard Cathedral in Christchurch, New Zealand.
Inspired by such designs, the RMIT University team has, for the first time, combined the durability of rammed earth with the versatility of cardboard.
Lead author Dr. Jiaming Ma from RMIT said the development of cardboard-confined rammed earth marked a significant advancement toward a more sustainable construction industry.
“Modern rammed earth construction compacts soil with added cement for strength. Cement use is excessive given the natural thickness of rammed earth walls,” he said.
But cardboard-confined rammed earth, developed at RMIT University, eliminates the need for cement and boasts one quarter of the carbon footprint at under one third of the cost, compared to concrete.
“By simply using cardboard, soil and water, we can make walls robust enough to support low-rise buildings,” Ma said.
“This innovation could revolutionize building design and construction, using locally sourced materials that are easier to recycle.
“It also reflects the global revival of earth-based construction fueled by net zero goals and interest in local sustainable materials.”
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Image of study lead author Dr. Jiaming Ma holding the cardboard-confined rammed earth material. Credit: RMIT University
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The RMIT-based research team. L–R: Hongru Zhang, Jiaming Ma, Dilan Robert and Ngoc San Ha. Credit: RMIT University
Practical benefits
The cardboard-confined rammed earth can be made on the construction site by compacting the soil and water mixture inside the cardboard formwork, either manually or with machines.
Study corresponding author and leading expert in the field of structural optimization, Emeritus Professor Yi Min “Mike’ Xie, said this advancement can spearhead a leaner, greener approach to construction.
“Instead of hauling in tons of bricks, steel and concrete, builders would only need to bring lightweight cardboard, as nearly all material can be obtained on site,” Xie said.
“This would significantly cut transport costs, simplify logistics and reduce upfront material demands.”
Ma said cardboard-confined rammed earth could be an effective solution for construction in remote areas, such as regional Australia, where red soils—ideal for rammed earth construction—are plentiful.
“Rammed earth buildings are ideal in hot climates because their high thermal mass naturally regulates indoor temperatures and humidity, reducing the need for mechanical cooling and cutting carbon emissions,” he said.
The mechanical strength of the novel material varies based on the thickness of the cardboard tubes.
Ma said the team has developed the formula for this strength design.
“We’ve created a way to figure out how the thickness of the cardboard affects the strength of the rammed earth, allowing us to measure strength based on cardboard thickness,” Ma said.
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An RMIT-created cardboard-confined rammed earth column. Credit: RMIT University
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An RMIT-created cardboard-confined rammed earth column. Credit: RMIT University
In a separate study led by Ma and published in Composite Structures, carbon fiber was combined with rammed earth, proving it had a comparable strength to high-performance concrete.
Ma and the team are ready to partner with various industries to further develop this new material so it can be used widely.
More information:
Jiaming Ma et al, Cardboard-confined rammed earth towards sustainable construction, Structures (2025). DOI: 10.1016/j.istruc.2025.110117
Jiaming Ma et al, CFRP-confined rammed earth towards high-performance earth construction, Composite Structures (2025). DOI: 10.1016/j.compstruct.2025.119512
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Tech
Best HelloFresh Coupons and Promo Codes for December 2025
Leveraging meal kit coupons is the extreme couponing of our times—a capitalism hack-a-thon right up there with trial yoga classes and attempting to cancel your Adobe subscription. Meal kits like HelloFresh have always been a better deal than they get credit for, even at full price: It’s actually hard to recreate meal kit meals for less than you can get the recipes delivered to your home. But it’s especially worth it when you can find a HelloFresh coupon, promo code, or discount at more than half off.
I’ll admit I wasn’t that sold on HelloFresh when I first tried it most of a decade ago. It was useful, it got me out of my staid routines, but I wasn’t impressed with the selection. It felt a little basic. But lately? Honestly, it’s kinda cosmopolitan these days, after expanding to a dozen countries and absorbing the supply networks from multiple other meal plans. When I last tested the HelloFresh meal kit (7/10, WIRED Recommends), I was surprised to find myself cooking credible home renditions of ramen, ponzu-plum beef stir fry, and Southwest-accented pork roasts. And when I’m able to pick up a HelloFresh discount code, it’s generally less than I’d spend on groceries anyway. So it’s a good moment to try out a lifestyle where the food comes in the mail.
Get 50% Off and up to 10 Free Meals as a New HelloFresh Customer
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HelloFresh Student and Discount: 55% Off, Free Shipping, Plus Extra 15% Off Education Discounts Available via UNiDAYS
HelloFresh meal kits are pretty amenable to dorm life when ordering the ready-to-eat meals—or just saving time during grad school instead of ordering pizza, by letting the Internet do your shopping and meal planning. But student budgets tend to be tight, of course. And so there are steeply discounted HelloFresh coupon codes specifically for students. Follow the link here for a HelloFresh education promo code offering 55% off your first box, free shipping, and a continuing discount of 15% off for the first year.
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Special Hero Discount for Military, Veterans, and Healthcare Workers
Military discounts are a long tradition in America. HelloFresh also offers hero discount programs for first responders, health professionals, and military personnel. Heroes also get excellent discounts that include 55% off the first order, free shipping, and 15% off for the first year of HelloFresh delivery boxes.
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Note that the hero discounts don’t combine with any other HelloFresh promo codes.
Give $40, Get $10 With the HelloFresh Referral Program
Already a HelloFresh subscriber? You’re still eligible for discounts if you pass along subscription information to your friends. Here’s how: Send your friends a $40 discount for their own affordable meal kits. Once they sign up using your HelloFresh referral code, you’ll also get a $10 credit on your next delivery.
These discounts stack. So if you sign up multiple friends with your referral code, you get multiple $10 discounts. Check out the HelloFresh meal kit referral program here.
Take Advantage of HelloFresh Come Back Offers
Some of these discounts are only available to new HelloFresh customers. But there’s a hack to getting discounts anyway. After you pause or cancel your subscription, check your inbox after the next few days or weeks. Often, you’ll get HelloFresh coupon codes for discounts.
Typical HelloFresh “come-back” offers after a canceled subscription include: $100 to $180 off (spread out over several meal boxes), free shipping on the first box (after re-subscribing), free items such as dessert, breakfast, or an extra protein per meal, or a free meal box is offered after a break. Typical retention offers, for when customers try to cancel, include: 40% off the next box, if you decide not to cancel, or 25% off the next two meal kits. None of this is failsafe, of course, offers vary for each customer. But as with magazine subscriptions, sometimes canceling, or trying to cancel, will lead to a good discount offer from a company eager to keep your business.
When to Save the Most on HelloFresh Subscriptions
HelloFresh almost always has some sort of deal going, whether to bring in new customers with an especially choice HelloFresh coupon, or bring back previous customers with HelloFresh discount codes and retention offers. But summer tends to be one of the times they offer the steepest discounts, including 10 free meals across several boxes, complimentary appetizers, free ready-made items, or free shipping on select boxes.
The other big times for HelloFresh coupon codes are around Black Friday and the end of the year. HelloFresh often launches limited-edition holiday meal boxes and themed meal kits, not to mention discounts for returning customers looking to cook more at home as part of New Year’s resolutions.
Tech
Could You Use a Rowboat to Walk on the Seafloor Like Jack Sparrow?
But you already know about this, because Fg is what normies call an object’s “weight,” and for a given volume, weight depends only on the density. Now, if you dropped these blocks in a lake, obviously the styrofoam would float and the steel would sink. So clearly it has something to do with density.
What if you had a block of water with the same volume? If you could somehow hold this cube of water, it would feel pretty heavy, about 62.4 pounds. Now, if you place it carefully in a lake, will it sink or bob on the surface like styrofoam? Neither, right? It’s just going to sit there.
Since it doesn’t move up or down, the total force on the block of water must be zero. That means there has to be a force counteracting gravity by pushing up with equal strength. We call this buoyancy, and for any object, the buoyancy force is equal to the weight of the water it displaces.
So let’s think about this. The steel block displaces the same amount of water, so it has the same upward-pushing buoyancy force as the block of water. But because it’s denser and has more mass, down it goes.
In general, an object will sink if the gravitational force exceeds the buoyancy force, and it will float if the buoyancy force exceeds the gravitational force. Another way of saying that is, an object will sink if it’s denser than water and it will float if it’s less dense.
And right in the middle an object will neither sink nor rise to the surface—we call that neutral buoyancy. Humans are pretty close to neutral because our bodies are 60 percent water. That’s why you feel weightless underwater—the buoyancy force pretty much offsets the gravitational force.
Avast! Hold on there, matey. Aircraft carriers are made of steel and weigh 100,000 tons, so why do they float? Can you guess? It’s because of their shape. Unlike a block of steel, a ship’s hull is hollow and filled with air, so it has a large volume relative to its weight.
But what if you start filling it with cargo? The ship gets heavier, which means it must displace more water to reach that equilibrium point. In general, when you launch a boat or ship into the water, it’ll sink down until the weight of the water it pushes aside equals the boat’s total weight.
Tech
The Ricoh GR IV, the Cult Favorite Pocket Camera, Just Got Way Better
When I reviewed the GR III, I wrote about how much I liked snap focus mode, which allows you to set a predetermined focus distance regardless of the aperture. I set up my GR III to use autofocus when I half-pressed the shutter and snap when I quickly pressed, so that snap focus fired off the shot at my predetermined focus distance (usually 1.5 meters).
All that remains, but there is also now a dedicated letter, Sn, on the mode dial that sets the camera in Snap Focus mode, which allows you to dial in not only the distance you want focus at, but also the aperture you want to lock in. You can control the depth of field as well. I rather enjoyed this new mode and found myself shooting with it quite a bit.
Should You Get One?
The GR IV debuted at $1,497, which is significantly more than the GR III’s $999 price at launch. Is it worth the extra money? If you have a GR III and are frustrated by the autofocus, I think you will like the upgrade. It’s significant and, if you have the money, well worth it.
If you have any desire to use your pocket camera for video, this is not the one for you. See our guides to pocket cameras and the best travel cameras for some better, hybrid photo- and video-capable cameras. If you want an APS-C sensor that legitimately fits in your pocket, offers amazing one-handed control, and produces excellent images, the the Ricoh GR IV is for you.
Personally, I am holding out for the GR IVx, which will hopefully, like the GR IIIx, be the same camera with a 40mm-equivalent lens. At the time of writing, Ricoh would not comment on whether there will be a GR IVx.
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