Quick Drying 3D Printed Clay-Hemp Polymer To Replace Concrete

Concrete’s Environmental Limits: Sand Use and CO₂ Emissions

Concrete has become the central material in construction over the past few decades, especially in dense urban environments. It has progressively replaced bricks, stone, and wood, thanks to its low cost, ease of use, and scalability.

But it is not without issues.

First, it is far from a sustainable product when it comes to resource consumption. It uses tremendous amounts of sand, to the point that reports suggest the world is “running out of sand.”

Source: Visual Capitalist

The production of cement is also a very energy-intensive activity. It is almost exclusively powered by fossil fuels, resulting in cement production being responsible for 8% of the world’s CO₂ emissions.

This is comparable to the emissions from cars and vans, which are responsible for 10% of global emissions. Consequently, making concrete more sustainable would be as impactful as transitioning all of the world’s cars to EVs and powering them only with green energy.

How Clay-Hemp 3D Printing Creates a Low-Carbon Concrete Alternative

Parallel to the search for greener alternatives to traditional concrete, the idea emerged of using 3D printing principles to build houses.

Instead of labor-intensive methods like bricklaying, an automated 3D printing machine can assemble walls quickly.

However, printing the walls does not eliminate the long curing time required for concrete; there is still a 28-day waiting period before the structure achieves full strength.

Researchers at Oregon State University have now developed a concrete substitute that is significantly less carbon-intensive while remaining compatible with 3D printing technology.

They published their results in Advanced Composites and Hybrid Materials¹ under the title “3D printing of sustainable infrastructure using rapid-set clay concrete with biobased additives.”

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Inside the Clay-Hemp Polymer: RICFP and Bio-Based Aggregates

Cement is typically comprised of calcium, silicon, aluminum, and iron, which are ultimately heated in a kiln and ground into a fine powder.

Instead, the researchers developed a 3D-printable, clay-based construction material using a method known as Radical-Induced Cationic Frontal Polymerization (RICFP).

It relies on three key chemical components:

• A monomer that polymerizes in the presence of a free radical.
• A crosslinker that links polymer strands together.
• An initiator that, under high temperature, releases the free radicals needed to start the polymerization.

The researchers achieved this by combining the RICFP binder with clay aggregate, sand, biochar, and hemp fiber to improve compressive strength, insulation, and sustainability. To this, a binder was added, made of acrylamide (ACR) monomer, methylenebisacrylamide (MBA) cross-linker, and ammonium persulfate (APS).

In total, this managed to use 70–80% bio-based materials by weight.

Source: Advanced Composites and Hybrid Materials

Superior Strength and Faster Curing Than Traditional Concrete

The main improvement this material provides compared to concrete is higher strength, especially immediately after 3D printing.

With a buildable strength of 3 megapascals (MPa), it enables the construction of multilayer walls and freestanding overhangs like roofs.

This strength increases over time, creating a very solid final building.

“It surpasses 17 megapascals, the strength required of residential structural concrete, in just three days, compared to as long as 28 days for traditional cement-based concrete.”

Devin Roach – Assistant Professor of Mechanical Engineering, OSU College of Engineering

Another advantage is cure time: the material reaches the 17 MPa strength required for residential structural concrete in just three days. It fully cures in under two weeks—compared with around 28 days for traditional cement-based concrete.

The researchers also tested different 3D printing construction methods. They demonstrated that higher strength and rapid polymerization enable the new mix to be printed without an underlying structure.

Source: Advanced Composites and Hybrid Materials

This new method could also be used to print normally shaped doors and windows, features that usually require extra materials or special methods with concrete 3D printing.

“The material’s ability to print free standing structure without the use of supports, including various and unique capabilities of printing with frontally polymerizing concrete.”

What Clay-Hemp 3D Printing Could Mean for Future Buildings

While 3D-printed houses and construction materials initially used concrete, it is likely that this novel construction method will benefit from new materials.

For now, as it is still at an experimental stage, the clay-hemp-biochar-based material is more expensive than concrete.

But further refinement and reduction in construction costs, thanks to 3D printing efficiencies, should ultimately bring it on par with traditional materials.

In addition, the superior carbon footprint could be a decisive factor if carbon taxes begin to impact cement costs heavily.

Investing in Cement Production

CRH: A Sustainable Cement Leader and Decarbonization Play

As one of the world’s leaders in cement production, CRH will be instrumental in turning cement construction into a more sustainable industry. It ranks #1 in total volume of construction material provided in both the US and European markets.

The company is active in 28 countries and 3,390 locations, employing 78,500 people, with CRH Americas making 65% of its 2023 global sales.

CRH expects robust spending by Western governments on infrastructure to help grow its business. The trends of re-industrialization and on-shoring high-tech manufacturing should also help.

Source: CRH

CRH has made serious progress in sustainability with a series of initiatives:

• It is the largest recycler in North America, with 43.9 million tons of waste and by-products from other industries recycled in 2023.
• It reduced its CO₂ emissions by 8% in 2023, thanks to using 36% alternative fuels in its cement plants.
• It is aiming for a reduction of emissions by 30% by 2030 (compared to 2021 emissions).

This is laudable in itself, but it can be seen as too little, too late, considering the carbon emissions of the concrete industry.

Luckily, CRH is also a driver of more fundamental changes to the sector. Notably, it has invested $75M into low-carbon cement company Sublime, together with the European concrete giant Holcim.

Sublime Systems was spun out of MIT in 2020 to utilize an electrolyzer to produce cement at ambient temperatures, replacing energy and fossil fuel-intensive kilns. It also enables the use of calcium sources as an input material, avoiding the release of CO₂ from limestone input.

Sublime’s first commercial facility in Holyoke is expected to open as early as 2026. If proven successful, it could be the real game-changer for the cement industry, and it could open the way to scalable low-emission concrete.

CRH also invested in other decarbonization and sustainability startups:

• €23.7 million in Cool Planet Technologies, developing carbon capture solutions for industries that have traditionally been difficult to decarbonize.
• $34.7M by CRH and other investors in Carbon Upcycling Technologies, using an all-electric mineralization solution to permanently store CO₂ in industrial by-products and minerals, like cement, plastics, consumer products, fertilizers, and pharmaceuticals.
• AICrete, a ‘recipe-as-a-service’ platform that works with local concrete producers, optimizing local materials and minimizing the amount of cement used using AI analyses, reducing both the CO₂ footprint and the cost of concrete production.
• FIDO AI’s Series B funding is a startup using AI to reduce water consumption and increase water savings.

Lastly, CRH is also investing in 3D concrete printing (3DCP) through its subsidiary Amerimix.

Overall, CRH is a profitable leader in the concrete and construction industry and is very actively preparing for the decarbonization of the industry, both directly in existing facilities and by being a prime provider of capital to innovative startups creating the next generation of cement and concrete production technology, including decarbonization and 3D printing.

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Study Referenced

^{1. Nicolas A. Gonsalves et al,. 3D printing of sustainable infrastructure using rapid-set clay concrete with biobased additives. Advanced Composites and Hybrid Materials. Volume 8. 01 October 2025. https://link.springer.com/article/10.1007/s42114-025-01456-1}