Material and Sustainable Building - Dissertation Example

Material and Sustainable Building Introduction In today’s world, lots of innovative techniques are being implemented for concrete homebuilding. These kinds of homes are usually lasts for a long period which indicates its longevity and also it requires quite a low maintenance. Like timber framed houses, these houses also have a very good quality that is these are also environmentally friendly. A concrete house has few in built features irrespective of the kind of building it is. These features include that of energy efficiency, peace and safety along with style and solid construction. Recycling waste and industrial byproducts are other core benefits of these houses. This is because waste material can be used while processing the cement, the core raw material of the concreted building. Apart from all these benefits, there is another important benefit, especially to the dwellers of such houses which make them feel safer and it is fire safety as these kinds of houses are more resistant to fire. While visiting the large urban areas, steel building is the most common sight. Practically, most of the buildings, those are commercial in nature, are constructed either of steel or steel framing underneath. Schools, churches, warehouses, air craft hangers and various other destinations are also made out of steel. Any building which can be made through wood can also build up with the steel and because of the strength, versatility and reliability and therefore most of the people are selecting steel when compared with other options. Now, as per the objective of the study that is compared in both the material can be presented through analysis of various important factors. Comparison between Concrete and Steel as the Material of Construction Scale Basically, the component of the stone can be separately as measured with various scales. One of the most important components is the stone or gravel. It can range in size from ¼ “to 1”. For small scale sculpture, generally larger than 1/4'” or 5mm is not required. Normally, stone is cheap compared to cement and it provides strength to the large construction works and also helps to control the shrinkage. Another important component is the silica fume. It is a waste product and a very dark fine grey powder. The sizes of the particle are around 1/100. This is basically the size of Portland cement. Concrete can gain double comprehensive strength if it used 8% as per the weight of Portland cement. It further helps to reduce permeability and increase density. Plastic fiber is the other ingredient. Fiber Mesh and Fiber Ad, those are the part of the Fiber additives are chopped at about ½” or at 1 cm. Fiber also add a small amount of tensile strength on a small scale. These things are almost invisible in the final products. The prime objective of the glass fiber is to include the tensile strength into the concrete used for the thin-wall forms. One of the special glass fibers, which are known as the ARGFs, is basically 12 mm long and it has been folded into the wet mix. The suggested concrete mixes using scale along with probable volume can be presented through a table. Scale of components Volume Very Small Scale   Stone dust 1 tbsp Portland cement 1 tbsp Metakaolin pinch fibers 1/2 tsp Metal filings 1/2 to 1 tsp     Mesh Sculpture   Sand 1.5 liters Portland cement 1 liter Stone dust 175 ml Metakaolin 80 ml Air entrainer 1/6 tsp Super plasticizer 1/2 tsp Fibers 1 to 2 tbsp Water (as little as possible)     Cast Sculpture   Crushed stone 8 to 16 liters Sand 8 liters Portland cement 4 liters Fibres 80 ml Metakaolin half liter Air entrainer 1 tsp air entrainer Super plasticizer 4 tsp super plasticizer There is also a technique for measuring the compressive strength of concrete. It can be measured through pounds per square inch and can be also denoted as PSI. One square inch of a concrete surface might hold XX number of pounds before crashing due to weight. A study revealed that concrete can handle 2000 to 3000 PSI, even before crashing some are withstand up to 12000 PSI. The weakest concrete which used for filling up the holes also can handle hundred pounds of weight per square inch. Regarding the tensile strength of steel can be measured in pounds per square inch. One important thing in this case is the point at which the steel actually began to stretch, it is known as the yield point and it has been measured through the thousands of PSI which is often abbreviated as KSI. Basically, one KSI equals to the 1,000 PSI. Steel which is used for the general purpose is known as Grade 40. It has tensile strength of 40000 pounds PSI or 40 KSI (Goss, 2006). Embodied Energy Basically at the primary stage of building of a house, energy is needed for transportation of the material but in case of concrete; it is produced locally utilizing the local resources. Normally those materials are manufactured with in the area of 100 kilometers of the construction site. Apart from transportation, a concrete made building provide for lifetime energy efficiency. Leaking of air is much lesser in concrete made houses in comparison with other material such as wood, steel and others and air leakage acquires a large percentage as the source of energy loss from a home. The most important characteristic that is the thermal mass properties of concrete is useful for increase efficiency of kind of building, domestic as well as commercial. The thermal mass of concrete delivers the year round benefits through storing and releasing the energy required for heating and cooling and through reducing temperature swing inside declining the cooling and heating costs. Insulation is helpful for minimizing energy loss through the building envelop. Basically modern concrete construction system uses technique, insulation, as well as thermal mass to build up an energy efficient building. Here it is important to mention that ICF, which is known as Insulating Concrete Forms, are the panels or the hollow blocks made of either rastra or insulating foam, are load up to form the shape of the walls then filled with reinforced concrete to make the structure. Embodied energy requirement for steel is high. It is about 34 GJ/ ton. Timber has lower embodied energy than the steel. Timber needs 13 GJ/ton where other metal like aluminum and chipboard have higher embodied energy. Those have 200 and 36 GJ/ ton respectively. Therefore, it can be stated that concrete made house has lower embodied energy because of the various reason such as transportation, leakage but the core material concrete has more or less similar embodied energy as steel. In case of the steel made house, the transportation issue should be considered as steel shits usually manufactured in different location and need to transport it far away. Therefore, it increases the embodied energy (Bioregional Reclaimed, n.d.). Embodied CO2 The cement industry has been considered as the one of the two primary producers of the carbon dioxide which creates up to 5% CO2 emissions worldwide. 50% of this is because of the chemical process and another 40% is from the burning fuel. The embodied carbon dioxide or ECO2 is in the range of 75-175 kg CO2/tone concrete. The emission of carbon dioxide from concrete manufacturing is directly proportionate with the mixture of cement in the concrete mix. For the fabrication of every ton of cement 900 kg of CO2 are emitted. Cement manufactures are the greatest contributor of the green house gases. It has been happening in two ways, when calcium carbonate has been thermally decomposed and at the time of using energy from combustion of the fossil fuels. For preparing steel, one need heat to prepare the sheet which has been used during the construction of any building. Therefore, it leads more carbon emission. Even in case of screwing up the steel sheets, electrical energy is needed. Therefore it has been proved that both heat and electronic energy is needed while building up a house. Nowadays, hydro-electric energy is used to reduce the carbon emission while manufacturing steel. Ecological Footprint and Ecological Rucksack Prior to explaining the impact of concrete and steel of economic footprint, it is necessary to understand the ecological footprint and ecological rucksack. The first one is the accounting tool, through which the environmental impact of a person’s lifestyle or process can be assessed. Ecological rucksack can be denoted as the total quantity of the natural material, which can be considered as the total input for manufacturing a product. This has been shown with MI factor. MI factor of steel is 21. It refers that one kilogram of steel carries 21 ecological rucksacks (Srinivash, 2001). Regarding the ecological footprint of the concrete, it can be stated that as for constructing a concrete house no wooden material is needed, therefore it does not require any CO2 observing trees. Concrete absorbs CO2 through carbonation throughout its life time and helps to reduce the carbon footprint of those houses that are built with concrete. In this case, steel is dominated by concrete but it is also helpful for reducing footprint through its recycling process. Recycling Concrete is suitable as a means for recycling both, industrial byproducts as well as waste. Silica fume, slag, flies ash all are used for making concrete. These are further helpful for reducing embodied energy, quantity of landfill materials and carbon footprint. Kiln dust is considered as the solid waste produced through cement manufacturing is also recycled back to the kiln as the raw material. Even the old concrete is also recycled and can be reused as the coarse fill for the road beds. To make cement, the manufacturer needs various waste products and industrial byproducts. It requires silica, calcium, alumina and iron and these products are provided from the coal combustion, power station and steel casting in form of ash, fly ash and foundry sand respectively. Another important issue is that of filling land. A government backed research team had found on March 3, 1983 that approximately 17% of the worldwide landfill was from concrete’s byproduct. In the year 2008, steel was the more recycled items. According to many of the researchers of this discipline, in United States more than 83% steel has been recycled. It has been also found that more than 60% metric tons of steel was recycled in 2000 (Papp, 2007). Among those, most recycled items are that of automobiles, appliances and construction materials. One study revealed that more than 97% structural steel and 106% of automobile steel has been recycled in 2008. The most important issue in this regard is that no inherent physical properties of steel have been lost during the recycling process. The energy saved by recycling of this product can be linked with the power consumption of home. It has been proved that 75% energy consumption can be reduced of this industry by recycling and that is sufficient to power eighteen million houses annually (Web Cite, 2008). Durability and Longevity As the appropriate building material, concrete is well known for durable construction and simply because of the longevity of concrete structures. In the wider sense concrete has more benefits than their longevity Through the Life Cycle Assessment (LCA) of functional units, materials can be compared regarding their sustainability. Life Cycle Cost Analysis (LCCA) can be used for more economic comparisons. It can be considered as the best technique to evaluate over-all-long-term economic efficiency for challenging alternative investment options. It is evident that longevity plays a significant role in LCCA or in LCA. A long lasting concrete house does not require reconstruction or rehabilitation frequently and therefore in the long run less raw materials are consumed, energy can be saved and congestion is reduced. In addition, well-designed and well-constructed concrete houses hardly need any maintenance over their lifetime. Regarding the durability, it can be stated that as the Portland cement was invented at the 1824, so it has been considered as relatively recent material. Even it can be taken into consideration that the modern high strength concrete will prove to be very stable and durable. There are concrete buildings in France, aged 130 years and still in very good condition. It is important to say here that all concrete are porous and durability can be considered as the key of porosity. Normally, the high strength concrete has lower porosity in comparison with the normal one. The compressive strength of concrete is about 56-60 N/mm2. Even the high strength concrete can provide 120-160 N/mm2. Therefore, concrete options often appear to be the beneficial ones, for their longevity and durability instead of the high initial investment or cost (European Concrete Paving Association, n.d.). Nowadays, steel building has become the choice of the home owner when the question is about the construction and the design of buildings of various sizes and shapes. The primary reason behind it is the durability of the material. Even steel has the highest strength – to - weight ratio among all the building metals. It eventually means that lesser amount of steel is required to erect a building due to its strength and durability. It further leads to saving up the construction cost. Most of the organizations are selecting metal while constructing office building, agricultural buildings and others. It has been observed that commercial steel building is common than the residential steel building but now the scenario is changing as more of the people are referring to this metal when constructing their house because of its unparalleled durability. Even farmers also give priority to this kind of building for their garages, barns and storage as steel offers a level of protection. Steel has high tensile strength of about 300 to 600 or 700 N/mm2. One important technical issue regarding the durability is that, changing the temperature from +200 to -600, the durability of steel can also be reduced and it has energy impacts too (Newsweaver, 2005). Environmentally Sustainable The concrete made houses are environment friendly. Concrete has been recognized as “green” with the growing concern of environmental factors. Basically, building with concrete reduces the exhaustion of the natural resources through reduction of the reconstruction requirement. The ingredients used for concrete made house are readily obtainable natural materials and cement. Those natural materials are the water, stone, sand and others. A very recent study had been revealed that it is very much realistic in the countries that have the most favorable recycling practices, to assume that approximately 86% of the concrete is usually carbonated after 100 years. During this period it used to absorb 57% of the CO2 released, all through the original calcinations. Within a short period after crushing concrete during recycling operation, more or less 50% of the CO2 has been absorbed. It is really a sustainable construction material. Only 7% to 15% cement is consisted with in concrete, which has been considered as the only energy-intensive ingredient. Through altering the raw material used in the manufacturing, the quantity of CO2 can be reduced in the cement manufacturing process. Portland - Limestone cement is gaining position across the world because of its environmentally friendly nature. It contains 10% extra limestone in comparison to 5% in regular Portland cement which further leads to 10% less CO2 emissions from production and there is no impact on the product performance. Performance wise both the concrete, made with PLC and made with regular cement is same therefore PLC based concrete can be used as replacement for the regular one. From a recent data, it has been known that 40% replacement have been done in Europe and in Canada, National Building Code has included PLC in 2010 but in USA approval of it is still under consideration. Like concrete, steel made houses are also considered as the environment friendly houses. The primary reason behind it is its recycling benefits. This factor enables steel framed houses to reduce the energy consumption. Therefore, it has greater impact on the environment. Possible Future Possibilities Concrete made houses are lacking in this case as once the construction has been completed, it become more difficult to destroy it or to reconstruct it. Attempting such action will be time consuming as well as costly. On the other hand, result is not same in case of steel. Steel framed houses basically are made up with steel sheets and that has been attached through screws. Therefore, at the time of making any modification screws can be removed and sheets can be designed as per the choice of the owner. Concrete Vs Steel Concrete and steel are the two main elements of a concrete building. All at the same time, they complement and contradict each other. Concrete and steel complement each other in a monolithic dome through working together to provide the dome its durability, longevity and strength. Considering the characteristic of each, it suggests contradiction. It can be clear through an example that steel is a metal where concrete is a rock and it has enormous compressive strength. It can be squeezed or compressed but has very little tensile strength. Tremendous loads can be given on concrete but it will not crush. In case of steel, it has enormous tensile strength which refers the ability to resist a force tending to split it apart. Therefore, it can be said that steel can resist tension or tearing. It is universal material which can be found all over the planet. Now it can be asked that whether steel and concrete can work together or not while constructing a building. Concrete and both have different characteristic, therefore they can be successfully work together. They will be complementary to each other in this case and one can provide what other lacks. Concrete and steel can be compared through the cost also. The price of steel starts from £500 per ton where as cost of concrete is only about £30 per ton. It shows a huge price difference in both the material which will play an important role while taking decision regarding the construction of house (South, 2009). Conclusion Therefore, finally it can be concluded that as the material for constructing homes, both the material is useful in one way or the other. From the above discussion it has been identified that concrete has dominated steel in few factors where steel also has dominated concrete in other factors. Apart from it, the choice of the material should be depended not only upon these factors but also according to the location of the building and climate of the place. As the topic is about environmental impact, therefore, it can be suggested that construction of building and choice of material should be on the Passive House standard. This standard has a great impact on the environmental issues and especially on the carbon foot print. References Bioregional Reclaimed, No Date. Embodied Energy. Environmental Impact Reduction. [Online] Available at: http://www.bioregional-reclaimed.com/Environmental%20Impact%20Reduction.htm [Accessed July 08, 2010]. European Concrete Paving Association, No Date. Durability and Longevity, Constituting a Cost-Effective and Environmental Advantage. Newsletter. [Online] Available at: http://www.eupave.eu/documents/activity-areas/sustainable-construction/sustainable-construction-durability-and-longevity-1.xml?lang=en [Accessed July 08, 2010]. Goss, A., 2006. Portland Cement. Small-Scale Concrete. [Online] Available at: http://www.makersgallery.com/concrete/concrete_worknotes.pdf [Accessed July 08, 2010]. IHS, No Date. Steel - Environmentally Friendly Material. Automotive Industry Trends. [Online] Available at: http://auto.ihs.com/news/newsletters/auto-v3i2-03.htm [Accessed July 08, 2010]. Newsweaver, No Date. The Durability of Steel Buildings. Residential Steel Framing. [Online] Available at: http://newsweaver.co.uk/sunwayhomeseurope/e_article000426924.cfm?x=b11,0,w [Accessed July 08, 2010]. Papp, J.F., 2007. Recycling- Metals. 2005 Minerals Yearbook. [Online] Available at: http://minerals.usgs.gov/minerals/pubs/commodity/recycle/recycmyb05.pdf [Accessed July 08, 2010]. South, D.B., 2009. Rock and Metal. Concrete and Steel: Complementary Opposites. [Online] Available at: http://www.monolithic.com/stories/concrete-and-steel [Accessed July 08, 2010]. Srinivas, H., 2001. What are Ecological Rucksacks?. GDRC. [Online] Available at: http://www.gdrc.org/uem/footprints/rucksacks.html [Accessed July 08, 2010]. Web Cite, 2008. 2008 Steel Recycling Rates. Steel Recycling Rates at a Glance. [Online] Available at: http://www.webcitation.org/5nge7f632 [Accessed July 08, 2010]. Bibliography CMRA, No Date. How Concrete is Recycled. How to Recycle. [Online] Available at: http://www.concreterecycling.org/how.html [Accessed July 08, 2010]. 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