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For centuries, historians have marvelled at the artistic techniques applied in building the ancient sites of the Colosseum and the Roman Forum. While civil engineers have been in awe at the construction techniques employed in building the Pantheon. Construction chemical suppliers and manufacturers, however, have been less interested in the wonders of Rome, as for years the recipe for making Roman concrete has been (for the most part) known; volcanic ash, lime (the product of baked limestone), and water.

But now it seems that construction chemical producers can still learn something from how the Romans made concrete, and it may well change thinking in the construction chemical sector. This is because a research team working at the US Department of Energy’s Lawrence Berkeley National Laboratory (Berkeley Lab) have used X-rays to microscopically analyse segments of Roman concrete and found that the use of seawater in building harbours and piers in the Roman Empire may have given the concrete extra durability.

As the Berkeley Lab website reports, “The team’s earlier work at Berkeley Lab’s Advanced Light Source (ALS), an X-ray research center known as a synchrotron, found that crystals of aluminous tobermorite, a layered mineral, played a key role in strengthening the concrete as they grew in relict lime particles.”
The research team believe that the tobermorite crystallized in the lime as the Roman concrete generated heat when exposed to sea water. This led the team to carry out a more detailed study of the harbor walls using an electron microscope to map the distribution of elements.

As the BBC reports, “The team also used two other techniques, X-ray micro-diffraction and Raman spectroscopy, to gain a deeper understanding of the chemistry at play.” This allowed the chemists to find, “significant amounts of tobermorite growing through the fabric of the concrete, with a related, porous mineral called phillipsite. The researchers say that the long-term exposure to sea water helped these crystals to keep on growing over time, reinforcing the concrete and preventing cracks from developing.”

Berkeley lab also notes how, “The minerals form fine fibers and plates that make the concrete more resilient and less susceptible to fracture over time. They may explain an ancient observation by the Roman scientist Pliny the Elder, who opined that the concrete, ‘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.’”

“Contrary to the principles of modern cement-based concrete,” said lead author Marie Jackson from the University of Utah, USA, “the Romans created a rock-like concrete that thrives in open chemical exchange with seawater.”

As the study states (pdf), “The cementing fabrics of Roman concrete breakwaters and piers constructed with volcanic ash mortars provide a well-constrained template for developing cementitious technologies through low-temperature rock-fluid interactions, cation-exchange, and carbonation reactions that occur long after an initial phase of reaction with lime.” It continues by outlining in detail how, “Roman marine concretes can provide guidelines for the optimal selection of natural volcanic pozzolans that have the potential to produce of regenerative cementitious resilience through long-term crystallization of zeolite, Al-tobermorite, and strätlingite mineral cements.”

While at present much of the research may seem like the abstract examination of old seawalls, the discovery is not only surprising, but also may lead to the development of improved modern concretes. As Berkeley Lab reports, “The work ultimately could lead to a wider adoption of concrete manufacturing techniques with less environmental impact than modern Portland cement manufacturing processes, which require high-temperature kilns. These are a significant contributor to industrial carbon dioxide emissions, which add to the build-up of greenhouse gases in Earth’s atmosphere.”

Knowing how concrete changes, and even grows, over time, could also be used to make a concrete that has less environmental impact. If that is the case, then the construction chemical sector could be on the edge of a new era.

Global governments are fighting for new ways to lower carbon emissions, the demand for concrete has never been higher, and the third world will soon be looking to construct the high-rise buildings enjoyed by the developed world. As ocean levels rise over the coming decades, the need to build sea walls will also increase, meaning that knowing what the Romans knew about concrete could help construction chemical suppliers everywhere.

Photo credit: University of Utah
Photo credit: JP Oleson

Adhesives have come a long way in recent years. The demand for ever stronger bonds has grown, as the need for replacing stitching, nails, and bolts has grown; and as materials have adapted, so have adhesives. Today, people are less likely to need to bind wood and metal together, as the use of rubber, plastic, ceramics, and glass has become more popular.

More modern materials, such as hydrogels, have even more elasticity, and are being used in all manner of places, for example modern robotics, contact lenses, and soft bone replacement treatments (such as in the vertebrae). They are called hydrogels because of the large amounts of water they contain, and they are highly adaptable materials.

However, up until now, there has not been an adequate adhesive to join two hydrogels together, as most modern glues turn rigid and stiff when they bond. When the hydrogels move, they create stresses and fractures in the adhesive, thus weakening the bond.

But now a team of researchers from Johannes Kepler University, in Linz, Austria, have developed a glue that is able to maintain high levels of flexibility, even after it has bonded.

The research team began by examining the properties of modern, household, superglue, and found that while it was a strong adhesive, “…it would not work [as a hydrogel adhesive] because when it dries, it becomes hard—that means that when two stretchy materials are bonded together, the glue cracks when both are stretched. That led them to conclude that what was needed was a non-solvent—a material that would not dissolve into the glue and would prevent it from becoming hard.”

The resulting adhesive, as the scientific journal Phys.org reports, “is a glue made with cyanoacrylates (the adherents in superglue) diluted with a non-solvent. When it is applied to two surfaces, the researchers explain, it diffuses into their outer layers and is triggered to polymerize by the water content, such as in a hydrogel. Put another way, they say that the glue becomes tangled with the polymer chains in a gel, creating a very tight bond—and thus far, it has worked really well.”

You can learn more about this discovery on the YouTube video here.

The highly successful results have been published in the online research sharing journal Science Advances. Where the report notes that the new adhesive is, “… a facile, universally applicable method for instant tough bonding of hydrogels to a wide variety of materials—from soft to hard—with unprecedented interfacial toughness exceeding the intrinsic fracture strength of the gels.”

The report continues by outlining exactly how wide a range of materials the glue was tested on, namely, “We carried out the 90° peeling tests of hydrogels bonded to poly(methyl methacrylate) (PMMA; 3 mm, Evonik Industries), PET (1 mm, Evonik Industries), PI (125 μm, Kapton DuPont), nitrile rubber (VWR nitrile examination gloves), polyisoprene rubber (460 μm, Oppo Band 8016), VHB4905 (500 μm, 3M), PDMS (Dow Corning Sylgard 184), Ecoflex (Ecoflex 00-30, Smooth-On), leather and bone (pork shoulder blade), chromium-coated metals (aluminium and copper), and chromium-coated glass and to hydrogels. We note that silicone elastomers (PDMS and Ecoflex) require surface pre-treatment with a commercially available primer (Loctite SF770, Henkel) to promote wetting of the adhesive dispersion; all other materials were used without pre-treatment.”

It is interesting to note the research team’s inclination to glue an electronic circuit to human skin. Whether this superglue will herald a new wave of consumer wearable electronics or not, remains to be seen. However, as hydrogels are permeable, the adhesive could be used to make flexible skins that delivery water soluble drugs, or adhere electronic sensors almost directly to the body. As the report notes, “We apply our approach to create a new set of soft machines and electronics and to demonstrate instant healing, adaptive optics, soft actuators and generators, tough batteries, and hydrogel electronic skins. Applications range from robotics, energy harvesting from renewable sources, consumer electronics, and wearables, to a new class of medical tools and health monitors.”

Clearly an adhesive of such versatility has numerous applications, for its water-permeability, coupled with the glue’s quick fixing time, its flexibility, its strength, and ultra-thinness, opens up a world of possibilities. Anywhere, where flexible, movable parts need to be connected – strongly – is a place where his glue could be stuck.

So where would you stick it?

Photo Credit: Soft Electronics Laboratory, Linz Institute of Technology

A lot has been written, in recent years, about the benefits of insect protein as an animal feed additive. Numerous studies have weighed up the pros and cons of insect meal, but with the industry expanding at a significant rate, it is clear that there are benefits to using insects as an additive to fish, poultry, and ruminant feed.

Perhaps most obviously, is the how simple the proces is to make protein additives for animal feed from insects. As the industry journal, TheFoodRush, describes, “When the flies have laid their eggs, the trays are transferred to a different container. There they will develop into maggots that eventually reach the end of the larval life cycle. At this moment, they will be put into a heater or dehydrator device to dry them out. Once dry, they can be ground into a flour-like substance that can be added to the meal used to feed livestock, poultry, or fish.”

The next biggest reason for using insect protein as a feed ingredient is demand. As the EU Commission’s CORDIS (Community Research and Development Information Service) states, “Europe currently imports 70 % of its protein for animal feed, putting it at risk from ever-growing competition for feed protein from a global population that is set to exceed 9 billion by 2050. Developing nations in particular are seeing a huge increase in demand for animal products, and there has been a five-fold increase in the total consumption of meat since the mid-1940s.”

However, there are plenty of challenges facing any new industry, and that includes the development of large scale insect protein production.

One of the largest problems facing Insect-For-Feed producers is legislation.

The industry is expanding, there is an evident need for a more sustainable protein feedstock, and yet the law is struggling to keep up with the pace of progress.

As Sarah Nolet, a consultant on food system innovation explains in a recent article on the agribusiness investor website, AGFunder, “Most countries lack a regulatory framework equipped to handle the potential risks (e.g., concerns over mad cow disease in Australia), while still allowing for innovations to enter the market. China is a clear exception, as they have an established regulatory framework, which is why companies like Protix have gone there to scale up production and establish traction.”

But now it seems that the tide has turned, and lawmakers are seeing the logic of environmentally friendly, sustainable, and circular economy insect farming for animal feed. As a report by the scientific journal, LabManager, states, “Until recently, insect-based feed was not allowed in the farmed fish industry in Europe. After years of discussions with European Union officials the EU Standing Committee on Plants, Animals, Food and Feed voted in December 2016 to allow insect proteins to be used in fish feed in Europe starting July 2017. [Although] only protein from eight insect species, including that from mealworms and two species of flies, are permitted.”

But there are still hurdles to be passed, even for using insect meal in petfood, as the industry journal, PetFoodIndustry.com, makes clear, “At the Association of American Feed Control Officials (AAFCO) meeting in January, the Committee indicated that new definitions for each insect, type of ingredient (flour, meal, protein concentrate, etc.) and intended species would need to be established first for the insect ingredients to be considered acceptable.” Adding that, “To date, only one insect, black soldier fly larvae (AAFCO #T60.117) has been defined, and that is limited to use in salmonid feeds.”

Pressure is growing though to pass legislation to further free up the use of insects as an animal feed raw material. This process has already begun in the EU, where, according to the journal FarmingUK, “The European Commission officially authorised insect-based processed animal proteins (PAPs) as feed for aquaculture animals on May 24, 2017, through a change to Annex IV of Regulation 999/2001, with the regulation text to come into effect on July 1 this year.”

However, many animal feed suppliers do not think that the legislation goes far enough, and are pressing, “… to allow ‘safe and sustainable’ insect-based feedstock for the pork and poultry industries.”

One such supplier is Mohamed Gastli, co-founder and CEO of insect farmer nextProtein, who believes that, “What must now be a priority is ensuring outdated regulations are amended to ensure safe and sustainable insect proteins can be used in the poultry and pork industries.

“Insect proteins are one of the most abundant sources of alternative proteins but until now the legal framework covering insect proteins needs has yet to fully catch up to the future of what businesses like ours can offer to modern agriculture.”

There has been significant media coverage on the need for a circular economy. The global and political will to combat climate change is present, and the need to increase global food production is well known, and yet many legislative bodies are reluctant, or simply too slow, to pass legislation allowing the increased use of insect meal as an animal feed source.

Already, two billion humans regularly consume insects as part of the diet, and yet we are concerned about the impact it will have on cattle and swine. Or even poultry, which have a natural urge to scratch and hunt for farmyard bugs.

If it is public opinion that is slowing down progress, then maybe we need to have an open debate about the advantages of insects as a protein source. For while it may seem unnatural to feed cows meal worms, growing acres and acres of corn and soybean for cattle feed isn’t very natural either.

Photo credit: Marcel Bekken