Foam Concrete, an environmentally friendly building material
If you want to rank Foam Concrete (FC) on how environmentally friendly (or damaging) it is, consider this list.
- Igloo made from snow.
- Mud bricks from locally found mud
- Log cabin in the woods
- Foam Concrete Dome shaped house
- Box type house made from Foam Concrete
FC compared to all those other building products and “normal“ concrete, because you can make a house with less cement, is less damaging to the environment.
Simply because it takes a lot of energy to make Portland Cement. About 7% of greenhouse gases come from the production of concrete.
It is also one of the lowest cost building materials, and if we can equate the costs directly with energy use, or greenhouse gas production, than we are way on top of the list.
Foamed concrete is simply a concrete mix with a lot of air in it and the aggregate left out. To get the air into the mortar mix, foam is mixed in. The foam is made from a special foaming agent and water and this mix is put through a foaming machine to create small bubbles.
The only disadvantage of this material is that it is not as “strong” as normal concrete; however there are special mixes that come close. There are also other ways to make a “light weight concrete” such as replacing the aggregate with polystyrene foam or expanded clay pebbles, pumice, and a few others.
The disadvantage of these are the cost, environmental impact and the difficulties in making the mix right.
Depending on the climate and geologic conditions, the construction can vary from light and simple to cold climate and earthquake proof.
I put the Dome shape into the mix as that it is the strongest form made with the minimal amount of material. This means that it can withstand cyclones and earthquakes much better than square buildings.
The building process does not produce the large amount of waste you see at the usual building sites. All FC spills can be used in the next batch, or used as a hard-fill
There are also a number of studies done to further reduce the environmental impact of FC. One study focuses on the Co2 reduction, and Concludes that FC is “better” than autoclaved lightweight concrete.
Replacing cement with Fly-ash is also one method to reduce the CO2 impact and Fly-ash can be cheaper than cement. Fly-ash is a waste product from coal fired power stations. Some experiments have replaced cement with Fly-ash up to 62% without reducing the MPa.
Addition of Fly-ash to the mortar also results in a higher strength.
I came across one study from China, replacing the sand with Iron Tailings. This is a waste product from a steel mill. Thus using an industrial waste and reducing the environmental impact of having to mine sand.
All these factors make a good argument to look further into the possibility to use this material, especially in the low-cost housing sector.
The knowledge and skill to construct houses is about the same as making them from “normal” concrete. The construction method can be making the house from bricks, precast panels, totally precast house and moved to site, and cast on site using formwork.
The main stumbling block now is the knowledge of the possibilities of Foamed Concrete. To overcome this, there is a website that brings all this together. Foamconcreteworld.com. Have a look at it.