Written by Morgan Kaenzig de Denus, AMAST Content

Image from buildabroad.com

If you haven’t heard of ferrock yet, you’re not alone. This carbon-negative, iron-rich compound was introduced in the early 2000s and has not yet gained widespread popularity. An excellent environmentally-friendly alternative to concrete, ferrock is created from byproducts of other processes and has notable potential uses in the construction industry.

What Is Ferrock?

Ferrock is created from a mixture of steel dust waste and silica, both of which are byproducts of other processes. When mixed with ferrous rock and water and exposed to carbon dioxide, this mixture hardens as a result of a chemical reaction between the steel dust waste’s iron and carbon dioxide from the air. As the iron in the steel dust waste absorbs carbon dioxide, iron carbonate is formed and the material continues to harden. The resulting product is strong, durable, quick to set, and carbon neutral.

Ferrock was invented by Dr. David Stone in 2002. An experiment-gone-wrong as he was researching how to prevent iron from rusting and hardening, ferrock was initially abandoned by Stone. After figuring out how to manufacture ferrock with the help of Tohono O’odham Nation Reservation and $200,000 worth of Environmental Protection Agency (EPA) grants, the University of Arizona was issued a patent for ferrock in 2013.

What Are the Benefits of Ferrock?

Ferrock is Strong
Ferrock is five times stronger than concrete. Ferrock’s strength is partially due to the presence of iron carbonate — a product of the chemical reaction that occurs between the steel dust waste’s iron and the carbon dioxide. Ferrock’s strength generally ranges from 5,000 to 7,000 psi, though some ferrock tests reached 10,000 psi.

In addition to being strong, ferrock has some flexibility. This flexibility allows ferrock to withstand more movement and pressure without cracking. In many cases, when faced with seismic activity or compression, ferrock won’t crumble.

It’s Environmentally Friendly
Ferrock Has Recycled Materials
Since ferrock is created from steel dust waste and silica, 95% of ferrock consists of recycled material. Steel dust waste is a byproduct of many industrial processes, while silica comes from ground-up glass.

Ferrock is Carbon Neutral
Like concrete and cement production, ferrock production emits carbon dioxide into the atmosphere. Unlike concrete and cement production — which are responsible for 5% of the world’s carbon dioxide emissions — producing ferrock can actually reduce greenhouse gases. When the mixture of steel dust waste, silica, ferrock rock, and water is exposed to air, the iron in the steel dust waste absorbs and reacts with carbon dioxide from the air.

Ferrock Sets Faster Than Concrete
While concrete takes between 24 and 48 hours to harden and up to 28 days to reach full strength, ferrock only needs around a week to completely harden. As it hardens, the glass fragments will fuse together and it will absorb carbon dioxide from the air, making it even stronger.

Ferrock is Durable
Ferrock is relatively chemically inactive. When it’s exposed to gases or chemicals, ferrock won’t deteriorate. Ferrock is resistant to rotting, oxidation, UV radiation, corrosion, chemicals, and rust, making it an ideal material for tubes and pipes. Ferrock is even strengthened by exposure to saltwater, so it’s often used in marine construction projects.

What Are the Drawbacks of Ferrock?

The main drawback of using ferrock in construction projects is that it is still very new. Having only been around since the early 2000s, no one knows ferrock’s full life cycle. Due to ferrock’s limited usage in the construction industry, it can be hard to come by builders experienced with using ferrock in projects.

While ferrock has been approved for use in slabs, pavers, bricks, sidewalks, benches, and walls, it has not been approved for use in roads or large structures yet. Currently, ferrock is used in marine construction.

What’s Next for Ferrock?

Ferrock will likely continue to grow within marine environments before it is more widely adapted. In the future, as more and more people continue to explore new methods of reducing greenhouse gas emissions and start to seek out carbon-neutral building materials, the demand for ferrock may grow.


Bonnefin, I. (n.d.). Emerging Materials: Ferrock. Certified Energy. Retrieved June 11, 2021, from https://www.certifiedenergy.com.au/emerging-materials/emerging-materials-ferrock.

Ferrock: A Stronger, Greener Alternative to Concrete? Build Abroad. (2017, January 29). Retrieved June 12, 2021, from https://buildabroad.org/2016/09/27/ferrock/.

Geiger, O, et al. (2017, June 6). Ferrock Concrete. Natural Building Blog. Retrieved June 7, 2021, from http://www.naturalbuildingblog.com/ferrock-concrete/.

How Is Ferrock Made? BuilderSpace. (n.d.) Retrieved June 8, 2021, from https://www.builderspace.com/how-is-ferrock-made#:~:text=Ferrock%20is%20a%20carbon%2Dnegative,steel%20dust%20waste%20with%20silica.

What Is Ferrock?Just Wood Furniture. (n.d.). Retrieved June 10, 2021, from https://www.justwoodfurniture.net/what-is-ferrock/.

Online Marketplace for Construction Materials serving contractors, vendors, and management companies — www.AMAST.com