Foam Concrete (FC)
An environmentally friendly building material
If I rank the FC on how environmentally friendly (or damaging) it is this is the list.
- Igloo made from snow.
- Mud bricks from locally found mud
- Log cabin in the forrest
- Foam concrete dome shaped house
- Foam concrete square shaped house
FC compared to all those other building products and “normal“ concrete, because you can make a house with less cement etc is less damaging to the environment. Simply because it takes a lot of energy to make Portland Cement.
It is also one of the lowest cost building materials. If we can equate the costs directly with energy use than we are way on top of the list.
I put the Dome shape into the mix as I believe that it is the strongest form made with the minimal amount of material.
The building process should also not produce the large amount of waste you see at the usual building sites. All FC spills can be used in the next batch.
It is also possible to recycle the FC. Demolish and pulverized on site, and use the “powder” in the next batch instead of sand. This depends of course if steel is used as re-enforcing how we deal with this.
There are also a number of studies done to further reduce the environmental impact of FC. This one focuses on the Co2 reduction, and Concludes that FC is “better” than autoclaved lightweight concrete.
The environmental impacts of foamed concrete production and exploitation
To cite this article: E Namsone et al 2017 IOP Conf. Ser.: Mater. Sci. Eng. 251 012029
The full version is available in the link. This study is interesting from the point of view that FC is not as bad for the environment as ACC concrete as the energy produced a for M3 is less. It does not take the Quality of Fc into consideration. I also included the conclusions of the report (9 pages).
Abstract. This paper presents a study focusing on the environmental impacts of foamed concrete production and exploitation. CO2 emissions are very important factor for describing durability and sustainability of any building material and its life cycle. The building sector is one of the largest energy-consuming sectors in the world. In this study CO2 missions are evaluated with regard to three types of energy resources (gas, coal and eco-friendly fuel). The related savings on raw materials are up to 120 t of water per 1000 t of traditionally mixed foamed concrete and up to 350 t of sand per 1000 t of foamed concrete produced withintensive mixing technology. In addition, total reduction of CO2 emissions (up to 60 t per 1000 m3 of material) and total energy saving from introduction of foamed concrete production (depending on the type of fuel) were calculated. In order to analyze the conditions of exploitation, both thermal conductivity and thickness of wall was determined. All obtained and calculated results were compared to those of the commercially produced autoclaved aerated concrete.
- Conclusions (copied from the report)
- Introducing production of foamed concrete by using gas will help to reduce total CO2 emissions by up to 34.62 t per 1000 m3 with regard to foamed concrete produced with intensive mixing technology and up to 30.5 t per 1000 m3 with regard to traditionally mixed foamed concrete.
- By replacing production of autoclaved aerated concrete with production of foamed concrete, the following savings in materials can be reached: water – up to 120 t per 1000 t for traditionally mixed foamed concrete, up to 55.3 t per 1000 t for foamed concrete produced with intensive mixing technology, sand – up to 349 t per 1000 t for foamed concrete produced with intensive mixing technology, up to 224 t per 1000 t for traditionally mixed foamed concrete.
- Lower value of thermal conductivity was reached for foamed concrete produced with intensive mixing technology with density class of D600 and with heat transfer coefficient U=0.18 W/m2K.
- Comparing to autoclaved aerated concrete, use of foamed concrete will save the wall construction material up to 10.5% by U=0.18 W/m2K.
Replacing cement with Fly-ash is 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 can make the MPa higher.
I came acres one study done in China, replacing the sand with Iron Tailings. This is a waste product from a steel mill.
Influences of Admixtures on Properties of Foam Concrete with Iron Tailings
There are a lot more publications on this topic, and I will list them if they are interesting enough. A lot of study is done on using locally produced waste materials in FC and concrete. How good these “solutions” are on the long term needs to be seen.
This website deals also with the “green” building topic: www.greenhomebuilding.com