Compressed Earth Block Construction: Advantages & Disadvantages

1. Introduction

From the beginning of humanity, one of the fundamental obligations is protecting themselves from weather, dangers or attacks, i.e. sheltering. In ancient times, the only option for seeking protection from natural dangers was caved. Later on, people found some methods to construct their living areas. Even in the modern age, everybody still needs to find shelter. Today, thanks to developments in technology, humanity has the ability to build by legions of construction methods. These can be exemplified by timber framing, reinforced concrete structures, earth-based structures etc. It is seemed to be that new and technological methods are popular in the sector, old and basic ones are preserving their importance, too. Besides new methods which are based on consumption are attracting for the market, earth-based construction methods can be eco-friendlier and more sustainable. In the context, this perspective has gained more importance in architecture. In this paper, it is mainly focusing on one of the earth-based construction method, compressed earth block (CEB) construction. It is a block consisting of earth-based materials. Also, it needs a compression process to be formed, which makes CEB special. Recently, it becomes more popular due to its cost-efficiency, sustainability, and health. In the following sections, a description of CEB, discussions about CEB, the comparison between advantages and disadvantages of CEB and possible future developments will be discussed in detail.

2. Compressed Earth Block (CEB)

Further thoughts, CEB is defined as “masonry elements principally made of raw earth, which are small in size and which have regular dynamic compression of earth in a humid state followed by immediate demoulding” (F.V. Riza & I.A. Rahman, 2014, s. 379). Clay, sand and silt compose soil which is transformed CEB. Moisture gradient of the soil should be 4-12% (P. Donkor & E. Obonyo, 2015). The compressed ground block, the most often known as adobe block, is a modern descendant of the moulded earth block. However, the idea that the earth should be compacted for improvements in its quality and performance is far from new, and the first compressed earth blocks were manufactured using wooden tamps. In some parts of the world, this process is still used. The first earth compressor machines probably date back to the 1 8th century. In France, Francois Cointeraux, inventor and fervent advocate of ‘ new pise ‘ (rammed earth) designed the ‘ crecise ‘, a device derived from a wine-press. But the first mechanical presses were designed with heavy tubes, forced into molds, only in the beginning of the 20th century. Even motor driven examples of this type of press. The fired brick industry continued to use static presses for the compression of the earth between two converging plates. However, after the invention of the famed little CINVA-RAM press, designed by engineer Raul Ramirez in Bogota, Columbia, the turn of the press use and of the use of compressed earth blocks for construction and architectural purposes took effect only in 1952. This was to be applied worldwide. In the 70 ‘s and the 80 ‘s the production and application of the compressed earth block was completed by a new generation of manual, machine and motor presses, resulting in the emergence of an authentic market today. The density of stabilized compressed soil bricks is typically found to be within the range of 1500e2000 kg / m3. The compressed earth brick density is consistently linked to its compressive strength and compact strength during production. The dry density mainly depends upon the characteristics of the component material, the humidity during pressing and the compactive load used and the compressive force controlled by density even in India. Density will also be affected by types of compaction, such as dynamic, static and vibrant. Standard processes such as ASTM C 140 and BS 1924-2 (1990) and others can be used to determine brick density.

Advantages & Disadvantages of CEB

It makes CEB safer when replacing cement or other materials with soil. Manufacturing of CEB does not need skilled laboring. Since CEBs are made up of locally available materials, they usually generate less waste, consume less energy and cost less. Also, the internal temperature and air conditioning of a building made by CEB are regulated due to its allowing the thermal mass control. Therefore, it provides an overall energy-efficiency for buildings. The nature of CEBs prevents any moisture due to clay. Because of this property, it can be said that buildings can breathe. In CEB buildings, humidity can be stabilized between 40 and 60 percent. In other words, indoor humidity can be regulated in CEB buildings, which can be considered as an air conditioning system. Thanks to this, the air quality of CEB buildings are better. In addition, the mixture of 30 percent of clay and 70 percent of sand is the most common one. It is important not to use too much clay (as well as liquid) unless blocks crack. The mass of CEBs resistant to earthquakes due to its thermal and acoustic properties. On the biological side, CEBs are natural non-toxic and fireproof materials.

On the other hand; the manufacturing process of CEB could be time-consuming. For example, the hardening process of CEB needs 28 days to be water-resistant. It is hard to find the correct mixture of materials such as soil, clay, concrete etc. Also, the height of CEB buildings is smaller than conventional ones because of intense. Similarly, the performance of CEB buildings is worse than concrete ones. If inappropriate production processes and materials are applied to CEB, their stability could be worsening. In fact, stabilizing CEB with adding extra materials could increase the carbon emission and environmental damages. For example, for holding the heat, it is necessary to add insulators to the mixture of CEB, if CEB is used for building in rainy climates (Kalale, 2014).

Future Developments

It is clear that there is an increasing trend on the researches of CEB. Unfortunately, it is still uncommon to use CEB in construction. Despite the fact that the cost-effective, long-term energy conservation and ease of use material points of view make CEB attractive (F.V. Riza & I.A. Rahman, 2014, s. 389). Nowadays, scientists are working on Martian Soil. Surprisingly, if a little pressure is applied, it is a good material for making earth-based blocks. Researchers at the University of California, San Diego, founded an easy method that Martian bricks which made up of a modified soil sample of the rover are stronger than steel-reinforced concrete. Lead researcher Yu Qiao said that “Our candidate research is on the materials level. We created coin-sized soil samples to scale up… We need something to lift the hammer and then release the hammer to hit the soil. That would create sufficient pressure to turn it into a brick.” (Lorek, 2018).

It is an obligation to limit the amount of material which will be transported from Earth to Mars if humanity wants to send humans to Mars (Beall, 2017). This will create some problems like building construction in Mars. Scientists had to find a method which is cost-efficient and easy so that they can solve this problem. In that point, future studies about Martian bricks may lighten them.

Another aspect of innovation in CEB is that people will be able to build their own homes by using locally available soils due to its interlocking shapes. This can add versatility and the still needed for building can be reduced, too. And portable and manual motor-driven press machines may motivate people to build their own houses. Moreover, future researches may expand the range of CEB materials with the scope of being greener and eco-friendlier (F.V. Riza & I.A. Rahman, 2014, s. 389).

Conclusion

In consumer societies, it is hard to ignore the ones which are in the current system. Investigators choose the easiest and cheapest way because the consumer demand is parallel to this situation. In this point, architectures come into all this with their original ideas. CEB is a perfect material for low high building constructions. Architectures could project in the direction of being eco-friendlier and more sustainable. If they deal with the advantages and disadvantages of CEB, it is possible to create a trend that is attractive for investigators. Even, local authorities and governments may support this concept which may be called “More Livable World”.

References

1. Beall, A. (2017, April 27). It’s much easier to make bricks out of Martian soil than we thought. Retrieved from Wired: https://www.wired.co.uk/article/bricks-martian-soil
2. F.V. Riza & I.A. Rahman. (2014). The properties of compressed earth-based (CEB) masonry blocks. In P. Chindaprasirt, Eco-efficient Masonry Bricks and Blocks (pp. 379-389). Jalan, Malaysia.
3. Kalale, P. (2014, January 20). Compressed Earth Block Construction: Turning Soil into a Sustainable Structure. Retrieved from Poplar: https://www.poplarnetwork.com/news/compressed-earth-block-construction-turning-soil-sustainable-structure
4. Lorek, S. (2018, March 21). SpaceX to Mars City: How to Build on Mars. Retrieved from Constructible: (https://constructible.trimble.com/construction-industry/spacex-to-mars-city-how-to-build-on-mars
5. P. Donkor & E. Obonyo. (2015). Earthen construction materials: Assessing the feasibility of improving strength and deformability of compressed earth blocks using polypropylene fibers. Materials & Design, 83, 813-819.