Earth is probably the oldest building material known and has been used in traditional construction in almost all the regions in the world for centuries. It has been used in the form of COB, hammed earth and adobe which are similar methods of construction that use soil and organic materials such as straw to produce sun-dried individual bricks or whole walls. After the creation of the fired clay brick, which can be mass-produced and is widely used in construction today, the use of these natural methods of construction reduced considerably. However, with increasing environmental awareness and search for more natural and sustainable methods of construction, these techniques are reviving and new advancements that use no wood for firing or formwork are becoming available.
Compressed stabilised earth brick (CSEB) is one of the technologies that increased in use in recent years. It was originally created as an alternative to adobe for low-cost construction as a stronger and more durable product, but nowadays it is used in all sorts of construction from low cost to high standard homes when a sustainable alternative to fired clay bricks or concrete blocks is desired.
Houses built with CSEBs
The production of CSEBs is done in three stages: soil preparation, compression and curing. The first stage consists of mixing suitable dry inorganic subsoil with a stabiliser and water. The most common stabiliser used is Portland cement in a proportion of 5% to 10% depending on the composition of the soil; it acts as the binding element that increases soil strength and durability. After producing an even mixture, the material is placed into a mould and compressed by using a manual or automatic press. Finally, the curing process starts by stacking the bricks and submerging them in water for several minutes , they are then removed from the water and placed in the shade to cure for around 28 days.
It is recognised that cement manufacture is an energy intensive process that has high embodied carbon but its use in this small amount in the CSEBs means that the final product is over 90% more energy and carbon efficient than its widely used fired clay bricks and concrete block counterparts. An alternative to cement is the use of lime in the mixture when appropriate, but there are also studies considering the use of enzymes and polymers as low-carbon alternatives to cement.
In addition to the environmental advantages of its composition and manufacturing process, the construction process with CSEBs is very economical when compared to fired clay bricks or concrete blocks as the final product has even surfaces, accurate dimensions and is interlockable, completely eliminating the need for any mortar between the bricks. Usually only small amount of appropriate brick glue is used. A wall made of CSEBs looks really neat with an exposed brick finish but if plastering is desired, only a very thin layer needs to be applied before painting.
There are many different shapes of interlocking CSEBs being developed and used around the world but the cleverest we have found is the CSEB with two holes. The system is composed of ‘two holes bricks’, ‘half bricks’ with one hole and channel bricks. The holes are used as receptacles for reinforced concrete columns eliminating the need for wood formwork and as voids for water pipes and electrical conduits, so there is no need to brake the bricks after walls are already built. The channel brick is used above doors and
windows and at ceiling level to act as permanent formwork for reinforced concrete beams, so again no wood is used and wasted. CSEBs can also be used in metal structure buildings as non- structural mansonry. Being a stackable system, it is very easy and quick to put together and can reduce build time by over 30%.
Another advantage of CSEBs is their thermal mass, which creates a very comfortable environment within homes both in summer and winter. They are also fire, sound and mould resistant as well as a non-toxic material and will not pose any threat to your family’s health. However, as it can absorb moisture easily, it is important to properly protect bricks from the rain and ground moisture by applying appropriate water seals.
There are many benefits of using CSEBs as mentioned above. In the UK it is yet to become a common product but as it is being widely manufactured and used in other countries we hope it will become popular soon. It is an eco-friendly alternative to fired clay bricks and concrete blocks and can be easily and quickly built. Consider using stabilised earth bricks on your next build and Green It Yourself…Now!