Ecological Performance
Monolithic Soil Based Rammed Earth
We chose to do the Rammed Earth Monolithic Soil Based wall system becasue we could find the most information on it. And figured it would be one of the most interesting types of wall systems for soil based walls.
Materials Flow Analysis
It is relatively easy to follow the life of Soil Based Monolithic Rammed Earth from to its underlying raw materials to its in-place position as part of a structure. Sand is the biggest component in Rammed Earth, weighing in a 70% of the total composition. Next is line is clay, taking up about 30% of the dry materials, leaving room for less than 1% for cement. Mixing these components together will create an amalgamation that will eventually be rammed into formwork; hence the name "rammed earth." The formwork for Rammed Earth is typically made of wood. The wood used is derived from trees. A finish on the exterior of the rammed earth wall is not necessary. Click here to view what Rammed Earth wall systems are made of.
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Supply Chain Risk Analysis
Five Year Analysis
Ten Year Analysis
Twenty-Five Year Analysis
References - Silica - Gypsum - Lime
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Materials, Energy, and Waste Whisker Diagram
The diagram above represents the matter and energy inputs to the monolithic soil based rammed earth wall systems. There are also materials and energy that come out of the construction of the rammed earth wall system. Equipment is used during the construction of the wall but it is shown to exit on the downstream side becasue they are temporary resources that are moved off the site at the end of the construction phase. Click here for source of diagram.
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Collateral Damage Analysis:
Rammed Earth is quickly becoming one of the new alternatives in green building around the country. However, because of the amount of compaction and ramming that the earth must undergo for completion, it is a very labor intensive process. Click here for an overview of some of the negative effects rammed earth has on labor and construction costs. This labor intensive process could lead to fatigue by many of the workers during construction because they are working in the heat. Along with its high price and labor costs, rammed earth can have a detrimental impact on the home if weather is inclement. Precipitation during the construction process can be devastating to the project and can lead to the destruction of the wall systems and foundation. Dry and humid weather is needed to ensure the security of the wall system. If not properly insulated internally and externally, water can ruin the rammed earth system by seeping through the earth and soil and possibly causing a slide. This could lead to the displacement of the foundation and the rammed earth wall system during construction and operation of the system; negatively affecting the construction of the system as a whole. Rain or water also makes it difficult for workers to perform their duties during construction. Another major factor that can negatively influence the use of rammed earth is the type of soil used. Soil can either be used from the jobsite at the foundation or can be brought in from a manufacturer. However, not using the right soil can cause a collapse to foundation during construction or operation, this can ultimately lead to the destruction of the system. Click here for an overview of the which soil to use during construction from a rammed earth builder. Cutting down trees for the excavation of the jobsite before construction begins can lead to the displacement of animals and the dispersal of carbon dioxide in the area and negatively impact the local ecosystem and environment.
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Collateral Synergy Analysis
Rammed Earth is an environmentally friendly type of wall system that is becoming more and more popular as we see an increasing need for environmental consideration. The installation of a rammed earth wall system is relatively simple. Although the actual ramming may be labor intensive, the system is very easy to understand and learn, allowing almost anyone to be able to participate in installation. There are no extensive skills necessary to produce a wall system other than formwork construction. These characteristics of rammed earth have a positive effect on the installers because it is such a simple process for them. The advantages that rammed earth offers also make it an impressive ecological choice. First of all, the composition of the actual rammed earth is almost completely natural. Using these naturally based materials limits the environmental impact, especially when there are no chemical or other hazardous releases during production. A majority of the material can be found directly on site. The clay found in the earth that is dug up for a foundation can be put directly in the wall system, and sand is a readily available material as well with zero impact on the environment when used. Furthermore, "rammed earth buildings have the advantage of having very thick walls that retain heat. Their thickness, or thermal mass, helps to even out temperature fluctuations between day and night, making them easy to heat and cool". This is yet another ecological advantage. Finally, the wall system is extemely durable. "Rammed earth buildings are extremely durable and can last for centuries. Experts claim that rammed-earth walls continue to harden - or cure, in their parlance - during the first year after construction". The resources required for a rammed earth wall system are renewable, ecofriendly and extremely durable.
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End-of-Life-Cycle Analysis
The expected life cycle of a rammed-earth wall is unknown as many historical buildings such as the great wall of china used rammed earth. All the materials used are highly durable and can last for the walls life-cycle. Rammed earth is very environmentally friendly and almost all materials come from the earth. There are three scenarios that are explained on how to dispose of the components of this wall type.
Scenario 1 - Dump Out Back
Unlike most systems, this approach is not too bad for the environment. Components such as water, clay, sand, and lime are easily decomposed and put back into the environment without causing any harm. Gypsum can cause a problem due to its ability to break down into sulfate ions which produces hydrogen sulfide, a gas that is toxic to fish and other life forms. Although very low levels of gypsum are in a rammed earth wall, disposal of the wall in the environment could cause toxic gas to leach into the soil or water. Silica is also a harmful chemical to leave in the environment. Silica crystals can cause silicosis, which can lead to lung cancer. Although this is very unlikely with the low levels used in the wall, caution should be used when deciding how to dispose of the wall. Wood is hardly used when building the rammed earth wall as it is only used in the formwork. The wood used is generally plywood and should be re-used and not left in the environment. Leaving a rammed earth wall in place when its reached the end of its life cycle does not cause horrid effects to the environment. However caution should be used when decided where to leave the components of this wall structure.
Scenario 2- Landfill
In this scenario, the components of the wall are taken apart and transoported to a landfill. This is the most common approach for builders as it covers all legal obligations and the wall is taken out of place. This idea also causes very little harm to the environment. Parts of the soil such as clay and sand will easily decompose in the environment but will not give any benefits by sitting in the landfill. Lime will also be released back into the environment and serve its natural purpose. Gypsum will ultimately be released as hydrogen sulfide which will seep into the soil and could harm environment. It is better to place gypsum into a landfill that is far from lakes or streams to prevent any harm to fish and animals. If disposing of the wood formwork, a landfill is a better approach than dumping out back so that no glue or treated wood is left in the environment. Although dumping in a landfill does not help the waste management problem in this country, minimal construction debris involved in the rammed earth wall is harmful to the environment and the quantity of harmful materials is minimal.
Scenario 3 - The Green Approach
The most environmentally friendly approach to destruction a rammed earth wall is to recycle. Unfourtunately, the rammed earth wall can't be taken apart as it is mixed as soil (clay, sand) and cement (lime,gypsum,silica). The wall is mixed before it dries so seperating the materials is virtually impossible, The best way to take down the wall would be to break down the wall find a suitable place to release the pieces. The clay, sand, and lime would decompose and create new topsoil for plants to grow and the minimal cement that is used should cause virtually no harm to the environment. The formwork used should be taken and used on the next rammed earth wall that is built and eventually disposed of in a landfill.
Rammed earth building is by far the most environmentally responsible way to build. It combines materials that came from the earth and puts them into a living environment for humans. Rammed earth was one of the first structure types used by humans and has proven to withstand the test of time. If the structure ever needs to be demolished, almost all components can serve their original purpose without causing any harm to the earth.
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Manufacturer's Claims Analysis
Proponent Claims
When using earth-building techniques, such as rammed earth, the act of construction practically uses no energy or any kind of pollution.. Soil is recyclable and because it can be dug right from the site, transportation (CO2 emissions) is usually not necessary. Rammed earth is very efficient when it comes to thermal productivity. The material provides thermal resistance, thermal storage, as well as efficient humidity regulation. The large thermal mass of a rammed earth wall stabilizes air temperature. As far as risks concerning environmental or human health, rammed earth itself has none. Many green building sites claim that it increases the indoor air quality.
Credibility and Reasonableness
Because rammed earth is recyclable and does not have manufacturers, information is taken from educational or websites dedicated simply for advice or guidance. One of the sites information was taken from was rammedearth.info. The sites credibility is under question. The author's name is not provided although there is contact information such as a telephone number and email to submit questions. Some claims seem to have no justification such as: rammed earth structures are sustainable for over a thousand years. However there was information that was backed by other websites. Information taken from Devon Earth Building Association appears to be a little more credible. There are no author's names but the claims all seem to be reasonable. The Association's purpose is to provide guidance for earth built structures.
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References
www.lime.org/environmental.html
www.nygypsum.ca/english/WA_DOE1990.pdf
http://content.karger.com/ProdukteDB/produkte.asp?Aktion=showproducts&searchWhat=books&ProduktNr=223692
http://en.wikipedia.org/wiki/Rammed_earth
http://www.devonearthbuilding.com/faq.htm
http://www.rammedearth.info/index.htm#Home
http://www.solumbuilders.ca/
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