When you are thinking about building a concrete home, one of the questions that may run through your mind could be, “Is concrete a green material? Is it a sustainable choice for my home?”
In this guide, we will go over what you need to know about the sustainability of concrete, as well as some types of green concrete.
First of all, in general, even traditional concrete is actually pretty sustainable. It is durable and long-lasting. Since a concrete structure can provide decades of use with little wear and tear, it is superior to a wood structure that would need to be repaired or replaced much sooner.
That said, there are now novel ways to improve concrete to make it even more sustainable.
What is Green Concrete?
When we are talking about sustainability, “green concrete” is a term that refers to specific types of concrete. There are two elements that go into making concrete “green”: methods and materials.
Sometimes, green concretes are referred to as eco-friendly concrete alternatives. While these sound like completely different things, they are just different terms referring to the same umbrella of products.
Manufacturers of green concrete use recycled and recyclable materials whenever possible.
One of the components of traditional concrete is cement. Alas, there is a large carbon footprint associated with cement. So, in green concrete, instead of using cement, manufacturers turn to other materials such as wood ash or silica fume. There are a lot of options out there that can work.
It isn’t just materials that are important when manufacturing green concrete. The methods that are used also matter.
The American Concrete Institute explains, “We will know that we are green when the industry has changed the way it thinks about, designs, builds, and uses concrete structures. When the environmental footprint of a structure is among the first considerations of a new project, we will be that much closer to the goal of sustainable construction.”
Other Meanings for the Term “Green Concrete”
Our focus in this post is on environmentally friendly concrete. But it is important to point out that the phrase “green concrete” has a few unrelated uses as well. American Concrete Institute lists this definition for green concrete in its glossary:
“Concrete that has undergone final setting but not hardened appreciably.”
As you can see, this has nothing to do with eco-friendly construction.
Sometimes, people also call freshly placed concrete “green concrete.” Again, this has nothing to do with sustainability. We just want you to know these definitions since you need context to know what someone is talking about when they mention “green concrete.”
Eco-Friendly Concrete Alternatives
You now have some groundwork for understanding green concrete in the context of sustainability. Let’s check out a few eco-friendly forms of green concrete that are environmentally-friendly alternatives to traditional concrete.
Hempcrete is a form of green concrete that consists of a mixture of hemp hurd, lime and water. The “hurd” of the hemp is the core of the stalk. When hemp is processed, it is a by-product which might otherwise go to waste.
Along with being eco-friendly, hempcrete boasts a number of other benefits. It is lightweight, insulates effectively, is resistant to fire and mold, and is hard to crack. Also, hemp itself is a sustainable crop, so that is yet another way in which hempcrete is eco-friendly. Find out about hempcrete in detail in our full hempcrete guide.
If you are after a concrete alternative that actually produces negative carbon emissions, then consider building your home out of ferrock. This material is a mixture of ground silica glass and waste steel dust.
Compared to Portland cement, ferrock is actually superior in many respects. For one thing, it resists cracking thanks to its flexibility. For another, it is significantly sturdier. You may also appreciate how rapidly it can set.
This material does contain cement, but it is mixed with waste sawdust. The carbon footprint for timbercrete is smaller than that of traditional cement. How much smaller depends on how high the sawdust composition is.
Using more sawdust means you can use less cement, which is good for the environment. It also means you can keep more sawdust out of landfills. The sawdust that ends up in landfills sometimes is burned as a source of energy. This is not good, since it is a huge carbon contributor.
The downside of having a high ratio of sawdust, however, is that the resulting timbercrete tends to be weaker and also less resistant to harsh weather. So, the key is to get a balance so you get the best of all features.
4. Straw Bales
It can sound strange to hear that a building was constructed using straw bales, but you would be surprised by just how strong and long-lasting straw bale construction is. In fact, the results are similar to what you can get from using concrete!
It might also startle you to learn that straw bales do not combust easily. They provide excellent insulation as well. There are some downsides though; if moisture gets into them, it can lead to rot and mold.
This material is made by mixing recycled fly ash, lime and water. The fly ash comes from combusting coal, and would otherwise go to waste. Ashcrete resists alkali-silica reactivity and is very strong.
6. Other Green Material Options
Along with the materials we just discussed, some other eco-friendly alternatives to traditional concrete include blast furnace slag, aggregate replacement, micro silica, post-consumer glass, concrete debris, rammed earth, plastic waste and composite cement. We would not be surprised if some more exciting materials are developed in the coming years.
Concrete has always been a sustainable building material compared to many others. But with the development of materials like hempcrete, timbercrete and ferrock, there are now quite a few alternatives that are even more sustainable. So, keep exploring materials and methods for concrete construction. You have many fantastic options for building a green concrete home.