While Part 1 of the article, "These unexpected ingredients are being used to fortify concrete" looked at food waste, diapers and crustaceans as possible ingredients for the manufacture of concrete, Part 2 will look at volcanic ash, wind turbine blades, plastic, PPE and even more food being used to fortify concrete.

Vegetables

Similar to the use of food waste detailed earlier in Part 1 in the making of concrete, researchers from Lancaster University in the U.K. are exploring how adding root vegetable fibers to concrete might improve the strength of the material as well as making it more eco-friendly.

Specifically, the team intends to explore how to incorporate nanoplatelets taken from the fibers of root vegetables such as sugar beets and carrots into concrete. So far, early tests have demonstrated the enhancement of concrete’s mechanical properties with the addition of the sugar beet and carrot nanoplatelets. The cement nanocomposites are created by combining Portland cement with nanoplatelets extracted from waste root vegetables.

By adding nanoplatelets to the mixture of water, aggregate and Portland cement, thereby increasing the amount of calcium silicate hydrate (which is responsible for increasing the strength of concrete), the team found that the mixture increased the strength of the concrete so much so that they needed 40 kg less Portland cement per cubic meter of concrete than with standard mixes, which means a corresponding reduction in the production of carbon dioxide.

Turbine blades

An Iowa startup is turning decommissioned wind turbine blades into an ingredient used in the making of concrete. REGEN Fiber has created technology that shreds decommissioned wind turbine blades into reinforcement fiber that will increase the strength and durability of concrete and mortar designed for use in applications like pavement, slabs-on-grade and precast products.

Fiber-reinforced polymer materials are derived from wind turbine blades. Source: REGEN Fiber

Volcanic ash

A team of researchers from MIT, Kuwait Institute for Scientific Research and Kuwait University suggests that volcanic ash — which is a mix of rock, mineral and glass particles expelled from a volcano during a volcanic eruption — can be a replacement for some of the Portland cement used in the manufacture of concrete.

The researchers are eyeing volcanic ash for such an application due to its natural availability and because some types reportedly feature pozzolanic properties. Specifically, in powder form, the ash with a reduced amount of cement can bind with water and other materials to create cement-like pastes.

Plastic

A team of researchers from MIT is reinforcing concrete formulations with plastic flakes.

Source: MIT News

In the lab, flakes of polyethylene terephthalate — material that is commonly used to make water and soda bottles — were exposed to doses of harmless gamma radiation. The flakes were then pulverized into a fine powder and mixed with cement paste. The resulting concrete was 20% stronger than conventional concrete, and the team suggested that the radiation treatment, which was performed in MIT’s cobalt-60 irradiator, altered and strengthened the material’s crystalline structure.

Following a battery of X-ray diffraction, backscattered electron microscopy and X-ray microtomography techniques, high-resolution images of the concrete featuring the irradiated plastic exhibited crystalline structures with more cross-linking, or molecular connections. Further, the crystalline structure also blocked pores within concrete, making the samples denser and subsequently stronger.

More plastic

A new kind of plastic-enhanced concrete is expected to improve plastic waste issues in Cape Town, South Africa.

Source: Center of Regenerative Design and Collaboration

Costa Rican-based company the Center of Regenerative Design and Collaboration (CRDC) is manufacturing concrete bricks using EcoArena pre-conditioned resin aggregate (PRA), otherwise known as shredded plastic, in Cape Town. Combined with a traditional sand and cement mixture, the plastic-enhanced bricks, which are lighter weight and stronger than traditional cement bricks, will be used to build houses, schools, hospitals and roads in Cape Town.

PPE

Masks worn amid the COVID-19 pandemic have overwhelmingly been discarded now that they are no longer in widespread use. Looking for a solution to the accumulation of discarded masks and the subsequent waste they leave behind, researchers from Washington State University (WSU) are using these one-time use masks to fortify concrete.

Diverting the disposable masks from the waste stream, the WSU team has made a concrete mixture featuring fibers from the disposable masks that is reportedly 47% stronger than traditional concrete.

Source: Washington State University

To accomplish this, the team devised a process wherein mask fibers (ranging from 5 mm to 30 mm in length) from deconstructed disposable masks are immersed in a graphene oxide solution before being immersed in the cement paste.

The researchers suggest that the graphene oxide creates ultrathin layers that adhere to the fabric fibers, thereby enabling them to absorb and dissipate the fracture energy that contributes to the tiny cracks that develop in traditional concrete and subsequently lends to larger cracks and eventual material failure.

Wood

Recognizing that furniture factories in Singapore can generate over half a million tons of wood waste annually, National University of Singapore (NUS) researchers devised a way to sustainably exploit the sawdust waste material derived from this industry and convert it into biochar featuring water absorption and retention properties.

The researchers display enhanced concrete (left) and a sample of biochar generated from wood waste (right). Source: NUS

According to the researchers, the recovered biochar can be incorporated into cement to improve the strength and water tightness of the material and enhance the curing and hardening of mortar and concrete, resulting in reduced construction time and cost by permitting early removal of formwork.

These are just a handful of examples of the different materials being used in the manufacture of concrete. Check back with GlobalSpec for more on these and other material innovations.