Design Life-Cycle
assess.design.(don't)consume
Melinda, Chen
Des40A
Professor Cogdell
5 December 2018
Clay Bricks Raw Materials
The production of bricks is a simple process which creates an ideal building material that generally lasts a long time. This process includes collecting raw clay minerals which is then mixed with water and fired. Bricks have an adaptable nature due to its flexible size, cheap production cost, and durability. The raw materials involved in the process of creating bricks often fluctuate from manufacturer to manufacturer depending on their needs and budget. For example, clay bricks made in more rural areas without access to machinery and extra minerals may choose to create a brick simply by mixing clay and water, while other large brick manufacturing companies may include additives such as barium carbonate to strengthen the brick. This allows for a lot of flexibility in the creation of bricks, making it one of the most common building materials. However, this flexibility also means that the raw materials and any additional chemicals that are chosen by different manufacturers will play a large role in the finished product. Therefore, it is important to understand which raw materials are used to create bricks and how these materials can maximize the efficiency of the brick production process.
It is important to consider the durability, color, texture, strength, and absorption of each raw material that is used throughout the brick making process, as all of these variables will have an effect on how the final brick behaves and how efficient it is. Clay bricks are the oldest and most used building material that can be easily manufactured wherever suitable soil is found. Natural clay materials such as soil is used as it is cheap, environmentally friendly, and very accessible. The production phase starts with the raw material preparation, then forming, drying, firing, and lastly packaging and transportation. Examples of commonly used natural clay minerals in the raw material preparation phase includes kaolinite and shale. There is an abundance of natural mineral materials on this planet which can be used in various diverse industries to create products such as ceramics, cement, and bricks. Kaolin and Shale are two examples of clays that are commonly used in bricks. Kaolinite is a clay mineral material that is layered with silicate mineral and linked through oxygen atoms. Rocks that are rich in kaolinite that are commonly used in clay brick production are known are kaolin. Kaolinite is one of the most common minerals that are naturally found in areas such as Vietnam, Brazil, China, and the United States, and is also used in the paper and plastic industries. This rock is a flexible material that has a low shrink-swell capacity making it soft and malleable which is suitable for forming bricks. Kaolin is usually white and is often mixed with iron oxide which changes it to a rusty hue. Iron oxide can also be used in glazes to increase its fluidity and change the color. Shale is a sedimentary rock that accounts for 55% of all of the rocks on the earth. This clay is subjected to high pressures until they have hardened into slate. Shale is a clastic sedimentary rock that is often easily breakable into thin layers which makes it easy to mix with other materials. These rocks are often used because of their plasticity, which allows them to be shaped and molded when mixed with water. This speeds up the manufacturing process as it can easily be molded into the correct size and shape for building. Furthermore, when choosing a clay it is important to take into consideration its strength when it is air dried. For example, Kaolin will dry when exposed to air below 100 degrees Celsius and will end in a “bone dry” state. Therefore, kaolin and shale are appropriate clays because they have sufficient strength when air-dried and are able to maintain their shape after being molded and dried. The high melting temperatures of Kaolin and Shale also allows the bricks to be sturdy and able to withstand high temperatures. These raw clay materials can easily be stored to use for later production regardless of weather conditions. Kaolin and Shale are just two examples of the types of minerals that can be used to make bricks, and the different properties show how each mineral will affect the final outcome.
The composition and type of raw materials chosen by the brick manufacturer can heavily affects the bricks properties, manufacturing process, and uses. A variety of these raw natural clay minerals are often mixed together in order to create the perfect chemical composition and physical properties needed for the brick. A high-quality brick is usually made from different clays that are blended together to achieve the maximum potential of the raw materials for brick production. The composition of the raw materials also affects how the bricks are manufactured. The manufacturing process includes adding water to the clay, forming it, drying, and firing. For example, depending on the raw materials, the amount of water added may need to be adjusted. Raw materials that have a higher water absorption rate may need less water in order to create a paste while some raw materials may need more water. Furthermore, the temperature of the firing kiln may also need to be adjusted for performance and efficiency depending on the raw material. Clay minerals such as kaolin have a very high melting temperature when used in brick creation and has to be fired in a kiln that is between 1,000 and 1,200 degrees centigrade. Other raw materials may have a lower melting temperature and may be able to be dried by simply laying it out in the sun. Therefore, it is important to consider the different ways that the composition of each raw material can affect the manufacturing process.
A variety of chemicals and additives can also be used in addition to natural clay minerals for different purposes to alter the color, texture, or durability of bricks. Not all bricks contain the same raw materials, and a basic handmade clay brick can be as simple as adding water to natural clay minerals and letting It dry. However, it is common for larger manufacturers to add other minerals throughout the process to create sturdier and more aesthetic bricks. The addition of other chemicals and minerals can also increase the efficiency of the brick production process. For example, chemical elements such as manganese and barium are often blended with the clay to produce different shades of bricks, as natural minerals are often white or uncolored like kaolin. Manganese can be used to create darker shades such as black while barium can create blue-greens. These can also be mixed together with other additives such as Potash, which has a yellow-green hue, to create different color mixes for the bricks. Manganese is a chemical that can be ground from natural ore materials such as raw umber, and is an easily accessible and cost-efficient way to color bricks. Chemical additives can also be used to strengthen the brick and increase its durability. Barium carbonate is often added to improve the brick’s chemical resistance to different elements. It can also be used in clay bodies to control scumming by rendering sulfates insoluble, in order to keep the bricks clean and free of dirt. The impurities from the raw clay materials such as kaolin can cause glassy discoloration and precipitated white powdery scum, which can be removed with the use of Barium Carbonate. The Barium Carbonate reacts with the impurities and sulphates to precipitate the insoluble products and control efflorescence. It does this by reacting with the soluble salts in the raw clay materials that cause this discoloration and hinders them from moving up to the surface. Other minerals that are added to bricks include sodium, potassium, and calcium. These minerals melt to form a silicate liquid, allowing the bricks to be altered more quickly in order to form its shape. This also creates a glassy coat for the brick and aids in the hardening process. Sand can also be added to the mix to improve the strength of the brick and to reduce its melting temperature so that the brick is easier to work with. This shows how different chemicals and additives can affect the brick in different ways, and how flexible the production of bricks are.
During the brick manufacturing process, coatings may also be applied to change and improve the texture or the surface of the brick. Glazes can help to create a smooth or sand-finished texture after forming the brick. This smooth texture is referred to as a die skin, which occurs as the clay passes through the steel die during the extrusion process. Finely ground clay or colorants may also be added throughout the manufacturing process to change the appearance. Clay slips and sand may be used in a glaze and fired onto the body of the brick during the manufacturing process to increase the hardness, or to create patterns throughout the brick. Glazes made of a slurry of clay and water may also be sprayed onto the brick to obtain different colors and to make the brick impermeable to water and water vapor. Finally, the finished bricks are secured together with mortar during the building process. Mortar is a binding agent that contains cement, sand, and water. Mortar is a workable paste that binds each individual brick together to form a wall. This paste is used in order to seal and fill the irregular gaps between the bricks to create a strong wall that serves as a base for building. The mortar can also be used to add colors or patterns in the walls.
In conclusion, a variety of raw materials can be used in the production of bricks depending on the producers’ available materials, budget, and desire for quality. These raw materials often include natural clay minerals, which then have other chemicals or minerals added to it. These additional chemicals and additives can be used to strengthen, purify, or change the composition of the clay bricks to suit the manufacturers needs. This means that the process of brickmaking can range from a simple process involving few materials to a large scale manufactured process involving various chemicals and machines. Therefore, this shows how versatile brick making can be and can provide insight into why bricks are one of the most commonly used building materials around the world.
Clay Bricks Bibliography
“Brick.” How Products Are Made, www.madehow.com/Volume-1/Brick.html.
“Production of Bricks from Waste Materials – A Review.” Construction and Building Materials, Elsevier, 10 June 2013, www.sciencedirect.com/science/article/pii/S0950061813004418.
Lee, James A., and Thomas O. Mason. “Brick and Tile.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 30 June 2016, www.britannica.com/technology/brick-building-material.
Brick, www.cement.org/cement-concrete-applications/paving/buildings-structures/concrete-homes/building-systems-for-every-need/brick.
The History of Bricks, www.dehoopsteenwerwe.co.za/information03.html.
Fennell, Natalie, and Laura Bilash. “Watch How Bricks Are Made - and See Why They're One of the Sturdiest Building Materials.” INSIDER, 10 May 2018, www.thisisinsider.com/how-bricks-are-made-2018-5.
“Bricks of the Trade: Ibstock Shows Us How It's Made.” Professional Builder, 14 July 2016, probuildermag.co.uk/features/bricks-trade-ibstock-shows-us-made.
“Making Bricks - Step by Step Manufacturing Bricks and Pavers.” Littlehampton Clay Bricks and Pavers, littlehamptonbrick.com.au/littlehampton-brick-about-us/making-bricks/.
Rodriguez, Juan. “5 Types of Bricks: Applications and Advantages.” The Balance Small Business, www.thebalancesmb.com/bricks-types-uses-and-advantages-844819.
Mustaq, Monamy. “Types of Bricks – Detail Classification of Bricks.” Civil Engineering, civiltoday.com/civil-engineering-materials/brick/191-types-of-bricks.
Shane Cooney
Des 40A - C. Cogdell
Research Essay
12/05/18
Life-Cycle Analysis of the Total Embodied Energy in Natural Clay Bricks
Naturally occurring clay is an abundant resource and is used in a myriad of building applications throughout the world. The earthen clay is extracted and manipulated to form long lasting, heat insulating, safe, and sturdy building blocks known as bricks. Given the 21st century’s global demand for affordable building resources, the construction industry is responsible for extracting nearly one quarter of the earth’s natural resources from the lithosphere -- demanding massive amounts of (non-renewable) energy and contributing equivocal amounts of toxic waste into the atmosphere. While natural clay bricks are an advantageous building resource and are inexpensive to produce, they require substantial amounts of energy to manufacture, process, and distribute, and are without energy efficient methods of reuse and recycling.
Clay bricks are comprised of a variety of different naturally occurring clays. As research implies, given “the difference in processes employed for manufacturing and the difference in composition of clay from region to region, a large variation is obtained in embodied energy of bricks” (Kua, 191). Furthermore, the embodied energy reported by various sources covers a range of figures: results which ranged depending on the year, location, and methodology used by brick manufacturers. What is consistent across all of the studies considered in this report is that the firing and drying process of curing the clay consumes by far the most embodied energy (~85%), followed by material extraction (~10%), and finally transportation, distribution, and end of life cycle procedures (~5%) . Overall, the total embodied energy required for the cradle-to-grave cycle of 1 kg of bricks is ~2.89MJ.
The first stage in the life cycle process of manufacturing clay bricks is material extraction. The initial acquisition process of removing bricks from the earth’s lithosphere requires heavy digging machinery powered by fossil-fuel based energy (diesel, petrol, and electricity). The size, average fuel consumption, and energy efficiency of these specific machines was not explicitly reported.
In general, however, the digging machines operate off of diesel -- which emits a myriad toxic pollutants such as Carbon Monoxide, Carbon Dioxide, Methane, and Nitrogen Oxide, to name a few. Furthermore, as mentioned above, this phase of production accounts for roughly 10% of the total embodied energy consumed.
Once the clay has been extracted, it is transported to a processing site. Depending on the region, the transportation of the raw clay to production facilities averages roughly 25 km --
and is carried using vehicles which typically consume diesel. The size and fuel efficiency of these cargo trucks varies by region and was not explicitly documented in any of the relevant reports. Consider the diagram above (courtesy of the 2005 study by Christopher Koroneos and Aris Dompros) as a reference to these transportation figures.
The second stage in the life-cycle of brick is processing and production. Once the raw material has been transported to the production facility, the clay is prepared to be molded and eventually baked, or fired, in a kiln. Before entering the kiln, the clay is mixed, smashed, and sifted: removing impurities so that the clay can be mixed with water. Once the water has been added, the wet clay is mixed and knead into a moldable paste, and is then cast into individual pieces; varying in size depending on the desired building application. These crushing and mixing processes are accomplished by diesel and electrically powered, industrial machinery.
Next, the wet clay bricks are dried in a facility which derives heat from the exhaust of the kilns used for firing the bricks, which, if done properly, can improve energy efficiency. In some cases, the bricks are set to air-dry for several days before they enter the next phase of production, depending on the plant. Following the drying procedure, the shaped bricks are transferred into a kiln, or furnace, and are ‘fired’ at high temperatures (+900 degrees Celsius) for several hours. These furnaces typically operate on fossil-fuel based energy, such as coal or petrol-coke -- but can also be substituted with bio-fuels such as sawdust or diesel oil. All of these fuel sources emit high levels of greenhouse gases into the atmosphere. Since bricks require an incredibly high temperature to be fired, this phase is by far the most energy intensive and wasteful phase of the life cycle.
A significant factor in the amount of energy required and waste emitted during the firing process is the inefficiencies of trapping and maintaining heat in the kilns and furnaces. In less advanced plants, kilns called ‘intermittent traditional kilns’ are employed -- which are significant contributors to harmful pollutants To understand the scale of the environmental and energy impact of these beginning procedures, considering the following statistic from a 2008 study: “the Asian brick making industry consumed about 110 million tons of coal and the diesel used for transportation produced approximately 180 million tons of carbon dioxide (CO2)” (Kua, 191). Importantly, these figures do not represent the total CO2 emissions of the entire process, merely those contributed by transportation.
Once the bricks are fired and cooled they are considered to be ‘finished’ and ready for packaging. Depending on the plant, the packaging can be done by either human labor, or machinery. In the latter case, the equipment typically uses electricity as its fuel proponent. Next, the brick is loaded onto trucks via diesel-powered machinery, destined to either a distribution center -- where the brick is prepared to be sent to various locations, or is transported directly to the site of use (typically for building structures). The aforementioned destination of the packaged bricks depends on the plant and region. These factors are accounted for in the overall embodied energy: if the bricks are transported to a distribution center, it is accomplished by large, diesel powered trucks. In referencing the above table 3 on page, the distance between the manufacturing site and the distribution facility is 32.5 km: a distance which requires a significant amount of diesel (87.26 kWh diesel energy / 48 kg of Clay) to power the transport trucks. Regardless of where the bricks are eventually distributed, it can be assumed that this process was achieved by heavy-duty, diesel-operated vehicles.
At this point in the life cycle analysis, the bricks have been fully processed and distributed and are ready for the next phase of being used in building applications. From this point forward, the plants which have extracted, processed, and distributed the bricks are left out of the equation. To consider and summarize the scale of energy required and the overall impact of brick production, consult the following data taken from a brick making plant in Greece:
Using these figures, the average amount of individual bricks produced annually is equivalent to ~1.25 million units (totalling 7,387,200 kg). Consequently, these practices rely on three main types of energy: diesel, electricity, and pet-coke. Furthermore, to better understand the total embodied energy, the cradle-to-grave energy requirement in 1 kg clay bricks (in a Singapore study) equates to roughly 2.89 MJ -- which is equivalent to ~0.8 kWh.
Once the finished bricks have been assumed by the builder, the bricks are assembled manually by hand. Clay bricks require mortar, which is essentially a cement which locks the bricks in place, to achieve their full potential as a weather, moisture, and flame resistant material. Throughout the reports surveyed for data collection, the use phase was not acutely documented: since the energy required in assembling bricks is measured by human-power, the overall embodied energy impact is insignificant when compared to other phases in the life cycle.
Clay brick has a lifetime of 80-100 years, depending on the weather and application. Throughout their use, bricks require significantly little maintenance, which decreases the total embodied energy required during their life-cycle. However, as much as the energy required for maintaining bricks is low, the potential for recycling the brick is energy inefficient and lacking of proper infrastructure.
The most common recycling practice of bricks is to ‘down-cycle’ by breaking the brick up into smaller pieces and employ it into the sub-base layers of roads or as a filler-substitute to reinforce concrete. In order to be broken up, the brick must be demolished. This demolition process, once again, involves diesel-powered industrial machinery. According to a study in Thailand, this equipment utilizes 0.0359 MJ of diesel per 1 kg of brick. In the same study, roughly 0.24 million tonnes of waste brick (the classification of brick after it has been reduced to smaller pieces) are conceived annually.
For a heavy, relatively low grade material like brick to be transferred locations -- as implied in the transportation phase -- demands a significant amount of energy. Thus, the location of the nearest recycling facility in relation to the demolition site is critical in determining the efficiency of recycling; the greater the distance, the increased usage of energy inputs (diesel) can in fact consume more energy than recycling would save -- in the greater picture.
In a country such as Greece, it is stated that “demolition waste... is used for landfilling purposes since there is no suitable plant for reduction and sorting of the waste material and reutilization of the demolition waste” (Koroneos, 2020). Thus, in instances where recycling infrastructure is unavailable or energy inefficient, the used brick ends its life cycle sitting in landfills. Fortunately, clay brick is inert and does not contribute to significant greenhouses gases as it decomposes on its own. In fact, a study by M.T. Brown and Vorasun Buranakarn considers that “overall, collection and landfilling costs are very small compared to the energy used in construction [of recycling bricks]. Essentially, then, recycling bricks becomes costly and energy demanding, whereas leaving them to rest in landfills is a cheap, relatively harmless alternative.
In order to reduce the embodied energy and overall environmental impact of manufacturing clay bricks, several solutions have been presented. The first, as mentioned earlier, is to have a more secure regulation of air-flow and heat maintenance throughout the firing process: there are opportunities for design innovations in creating furnaces which better trap heat, and which use less energy. Additionally, sun-drying the bricks before they are fired is an effective, energy reducing method. Ultimately, since the greatest environmental impact of bricks comes from fossil-fuel emissions, it is suggested that to use cleaner fuel (ones with lower sulfur contents) would greatly reduce overall toxic emissions. However, within the scope of studies analyzed herein, there was a shortage of information on the exact cleaner fuel alternatives and sustainable practices and how these are projected to reduce the embodied energy.
A blossoming alternative process of brick production -- which resorts to pre-industrial practices for producing bricks is in growing numbers today -- specifically in developing countries. These methods serve as a cost/energy effective method of reducing the environmental impact of brick production. For instance, The Clay Brick Association of South Africa, known as “CBA” has several initiatives which support ‘micro-enterprises’: local, informal brick-making operations that rely on traditional, labor-intensive practices to harvest and fire bricks. As much as these practices are far better for the environment, they cannot keep up with the demand of the growing infrastructure throughout the world. Even though brick making has been conducted by humans for thousands of years, there are alternative building techniques, such as ones that upcycle lumber, denim, and plastic, which prove to be far less impactful on the environment and consume far less energy in their life cycles.
BIBLIOGRAPHY
Bribián, Ignacio Zabalza, et al. “Life Cycle Assessment of Building Materials: Comparative
Analysis of Energy and Environmental Impacts and Evaluation of the Eco-Efficiency Improvement Potential.” Building and Environment, vol. 46, no. 5, 2011, pp. 1133–1140.
“Brick Builds Better.” Home, www.gobrick.com/.
Brown, M.t., and Vorasun Buranakarn. “Emergy Indices and Ratios for Sustainable Material
Cycles and Recycle Options.” Resources, Conservation and Recycling, vol. 38, no. 1, 2003, pp. 1–22.
“BRICKMAKING in the USA: A BRIEF HISTORY.” BRICK COLLECTING .Com,
brickcollecting.com/history.htm.
“Clay Brick Association of South Africa.” Clay Brick Life Cycle Assessment (LCA) | Clay Brick
Association of South Africa, www.claybrick.org/LCA.
Harris, D.j. “A Quantitative Approach to the Assessment of the Environmental Impact of
Building Materials.” Building and Environment, vol. 34, no. 6, 1999, pp. 751–758.
Koroneos, Christopher, and Aris Dompros. “Environmental Assessment of Brick Production in
Greece.” Building and Environment, vol. 42, no. 5, 2007, pp. 2114–2123.
Kua, Harn Wei, and Susmita Kamath. “An Attributional and Consequential Life Cycle
Assessment of Substituting Concrete with Bricks.” Journal of Cleaner Production, vol. 81, 2014, pp. 190–200.
Lin, Kae-Long, et al. “Recycling Waste Brick from Construction and Demolition of Buildings as
Pozzolanic Materials.” Waste Management & Research, vol. 28, no. 7, Dec. 2010, pp. 653–659.
Pérez-Hernández, A., et al. “Life Cycle Assessment of Regional Brick Manufacture.” Materiales
De Construcción, vol. 66, no. 322, 2016.
Sahu, M.k., and R.k. Patel. “Methods for Utilization of Red Mud and Its Management.”
Environmental Materials and Waste, 2016, pp. 485–524.
Thormark, Catarina. “A Low Energy Building in a Life Cycle—Its Embodied Energy, Energy
Need for Operation and Recycling Potential.” Building and Environment, vol. 37, no. 4, 2002, pp. 429–435.
Allan Hom
995910137
DES 40A. A01
Cogdell/ Saremi
Clay Brick Life Cycle: Waste and Emissions
As a major building material, fired ceramic, also known as clay brick, has been used throughout generations for its durability and heat resistance. Described by Professor Christina Cogdell at the University of California, Davis, the earliest fired brick in architecture is recorded back to c. 3000 BCE. These compression structures were consisted of mud, clay, and straw bricks to be dried in the sun, combined with other materials, and then to shaped for appliances and structures ultimately impacting their civilization in terms of energy expenditures and wastes. Over time, clay brick’s usage continued to be used for construction of buildings and new types of blocks made of different materials were created, such as fly ash, engineered, sand lime, and concrete bricks. This process of brickmaking has relatively stayed the same with slight adjustments in conjunction with the advancement of technology. Though some will advocate for brick’s durability, insulative properties, and even aesthetic appeal, clay brick production is severely harmful for the environment and all aspects of life considering the high levels of greenhouse gasses emitted in addition to the depletion of non-renewable sources during the process, therefore alternative materials and methods should be assessed when it comes to the construction of buildings and appliances.
Depending on the geographic region, the raw materials required to produce clay bricks are extracted directly from the earth’s crust, which influences the chemical makeup of the product itself. Generally, the composition of clay is silicon dioxide (SiO₂), Aluminium oxide (Al₂O₃), and impurities (CaO). Encyclopedia Britannica declares that “Clays used in brickmaking represent a wide range of materials that include varying percentages of silica and alumina. They may be grouped in three classes: (1) surface clays found near or on the surface of the earth, typically in river bottoms; (2) shales, clays subjected to high geologic pressures and varying in hardness from a slate to a form of partially decomposed rock; and (3) fireclays, found deeper under the surface and requiring mining. Fireclays have a more uniform chemical composition than surface clays or shale.” Surface clays are usually extracted with power shovels, bulldozers equipped with scraper blades, and dragline operations. Shales are obtained by means of blasting and power shovels, and fireclays are mined through conventional techniques. This extraction process known as clay ‘winning’ results in the usage of machinery and the expenditure of energy, leaving behind carbon footprints. When there is unavailable land to obtain the raw materials needed to produce clay, it is possible to source the raw materials from clay pits, which are mines or quarries used for storing and extracting clay to be used for pottery, bricks, or mixed with other materials such as cement. These pits reserved for clay extraction disrupts and often destroys the interconnected ecosystem of native plants and fauna. Furthermore, a related study in the LCA of clay brick walling in South Africa noted that “With respect to Human health, the impacts in the clay preparation phase come from the coal and originate from the emissions caused at the coal mine during extraction, whereas during firing, particularly damaging emissions are sulphur dioxide, Dioxin 2,3,7,8, Tetrachlorodibenzo-p, nitrogen oxides, particulates and ammonia..” In addition to degradation of natural landscape for the extraction of raw materials needed to produce clay bricks, the transportation from the pits to the manufacturing process will also require cargo fuel, resulting in varying emissions of carbon dioxide (CO2 ) depending on the distance traveled. On an individual scale, miners are also exposed to dust that results from these extraction methods. Research was unable to confirm if water extraction occurs in these processes. When considering the need for biodiversity within our landscape to sustain our crops, winning raw materials and clay pits required for brick production are not conducive towards a sustainable environment.
After mining of primary raw materials to be manufactured into secondary raw materials before the formulation of a final product in clay bricks, these steps reveal manufacturing as the most concerning issue involved in its life cycle assessment in terms of waste and emissions due to the firing of the brick. Following extraction is forming the clay brick’s dimensions; shape and size, which can be achieved in three different ways; extrusion, stiff-mud process where clay is mixed with an appropriate amount of water to enable plasticity, molded (soft mud), and dry pressed, as detailed The Brick Industry Association. After this step from the molding and cutting machines, the bricks are set to be dried; water is evaporated in dryer chambers at temperatures ranging from 100 to 400 degrees Fahrenheit for 24 to 48 hours, depending on structure. This regulation of heat and humidity must be carefully accounted for in order to avoid any cracking in the brick. Lastly, firing is one of the final stages of clay brick production, and directly impacts air quality in a negative manner. During this process for clay brick manufacturing, the burning of fuel for firing bricks results in emissions of gaseous pollutants and ash into the environment. Indeed, with such high embodied energy expenditures and output of CO2, the firing of bricks also emits various pollutants like chlorides, fluoride, sulfur, oxides of nitrogen. A chart published by The National Pollutant Inventory in 1998 confirms these toxins are emitted, with air affected by particulates, water contaminated with metals, and handling wastes also present.
Also illustrated in the same study is that when clay bricks are fired in kilns, substances emitted range from cobalt, lead, nickel, arsenic, mercury, and beryllium.
Firing kilns used in the clay brick production requires energy and the burning of coals, leading to carbon emissions, as well as water extraction to bind the clay to reinforce its shape throughout the process. The large carbon footprint that is left behind amounts to various toxic chemicals harmful to all aspects of life. After the clay bricks are fired dried and then cooled, they must be transported and shipped in some manner, resulting in more carbon emissions. The amount of clay bricks compared to the amount of space and handling load for this heavy material will also likely result in multiple trips, thus increasing toxic emissions as well.
Little research was conducted on distribution and transportation of getting the material to the stores and the consumers due to limited sources on this topic. However, cargo emissions of CO2 and other greenhouse gas emissions is obvious when clay bricks are transported by car or train. In more rural areas, loads of clay bricks are seen to be handled on boats with the prime movers as men or even animal. In an article by international animal welfare charity Brooke, south Asian brick kilns are explored, and through this it is evident that pack animals such as donkeys, mules, and horses are transporting the heavy material. These animals may be led by young boys and even women, exposing them to dust and other particles while handling the materials and other duties involved.
Once consumers obtain the clay bricks, their usage is predominantly construction and building material. It is worthy to note that their use phase can also involve the burning of coal, which has been documented to increase greenhouse gas emissions. Though clay bricks are built to last 100 years or more, according to the International Association of Certified Home Inspectors (IACHI), they can be reused if they meet certain safety guidelines. Due to the composition of clay brick, it features numerous physical advantages, such as its porosity, temperature resistance, and overall low maintenance, but the firing required for reuse of salvaged clay bricks would also result in more fossil fuel emissions.
Bricks are categorized under construction and demolition waste. They require the specialized disposition from a contractor or construction and demolition recycling plant. After the brick is collected, it can be pulverized into gravel-size pieces and used as ground cover for yards, as substitute for mulch, and into powders to be incorporated into baseball diamonds, running fields, and onto tennis courts. The Brick Industry Association also claims that “most brick manufacturers use recycled content when making new bricks, which likely results from recycling old bricks.”
In regard to waste management, bricks consist of natural raw materials, so they have no harmful side effects when they come into contact with ground or surface water; the mineral structure allows it to be reused after recycling for infrastructure works, aggregation to precase concrete and mortar, and plant substrates. Bricks that cannot be reclaimed after demolition and unable to be combined with other materials will result in occupying landfill.
The design of buildings relies on many materials and methods, and according to the U.S. Energy Information Administration, buildings are responsible for about half of U.S. CO2 emissions (44.6%). In consideration of the entire lifecycle, the processing of clay bricks expresses the most damaging effects to life, as prolonged exposure to greenhouse gases has indicated exacerbation or increased susceptibly to respiratory issues. From pisé, or rammed earth, to the Ziggurat of Ur, and then extending towards the Great Wall of China, brickmaking has been pivotal in the construction of these monuments and other structures. Though clay bricks continue to boast superior moisture control as well as protection from hazards such as fire and storms with their timeless look and feel, the environmental implications far outweigh these benefits from using clay bricks as a source of building blocks. In some parts of the world such as China, clay is scarce and continues to be a non-renewable resource as it is extracted from the earth, as indicated by the China Economic Trade Committee. The clay brick production process continually contaminates human health and contributes to global warming, and in an embodied energy data compilation by Auroville Earth Institute in 2013, the carbon emissions are 8.8x greater compared than compressed earth block structures, further establishing the need for more sustainable materials and methods in construction buildings.
Sources:
1. “Brick.” Wikipedia, Wikimedia Foundation, 21 Nov. 2018, en.wikipedia.org/wiki/Brick.
2. “Global Mitigation of Non-CO2 Greenhouse Gases: Coal Mining.” EPA, Environmental Protection Agency, 9 Aug. 2016, www.epa.gov/global-mitigation-non-co2-greenhouse-gases/global-mitigation-non-co2-greenhouse-gases-coal-mining.
3. Mason, Thomas O., and James A. Lee. “Brick and Tile.” Encyclopædia Britannica, Encyclopædia Britannica, Inc., 31 Oct. 2018, www.britannica.com/technology/brick-building-material#ref76609.
4. “Why Choose Brick?” Home, www.gobrick.com/why-choose-brick.
5. “Researchers Track the Environmental Impact of Brick Kilns in South Asia.” Phys.org - News and Articles on Science and Technology, Phys.org, phys.org/news/2017-09-track-environmental-impact-brick-kilns.html.
6. “Home.” Vandersanden Group, www.vandersandengroup.com/group/en/eco/bricks-durable-and-ecologically#recycling-and-reuse.
7. “Clay Brick Association of South Africa.” 500 Years Is the Average Brick Lifespan | Clay Brick Association of South Africa, www.claybrick.org/technical-note-30-lca-environmental-impacts-clay-bricks-south-africa.
8. “Clay Brick Association of South Africa.” 500 Years Is the Average Brick Lifespan | Clay Brick Association of South Africa, www.claybrick.org/lca-life-cycle-clay-brick-and-why-it-matters.
9. “Bricks: Fired / Unfired Clay, Reclaimed & Calcium Silicate.” Greenspec, www.greenspec.co.uk/building-design/bricks.
10. “ENVIRONMENTAL POLLUTION FROM BRICK MAKING OPERATIONS AND THEIR EFFECT ON WORKERS.” The Environmental Impact by Nearby Businesses, 8 Jan. 2012, businessimpactenvironment.wordpress.com/2011/10/03/environmental-pollution-from-brick-making-operations-and-their-effect-on-workers/.
11. “How Buildings Impact the Environment.” BOSS Controls, 27 Sept. 2016, bosscontrols.com/buildings-impact-environment/.
12. “Organisations Join Forces to Tackle Invisibility of South Asia's Brick Kilns.” Emma Goodman-Milne Q&A | Brooke, 26 Jan. 2017, www.thebrooke.org/news/organisations-tackle-invisible-south-asia-brick-kilns.
13. National Pollutant Inventory, www.npi.gov.au/resource/emission-estimation-technique-manual-bricks-ceramics-and-clay-product-manufacturing.
14. “Production of Bricks from Waste Materials – A Review.” NeuroImage, Academic Press, 10 June 2013, www.sciencedirect.com/science/article/pii/S0950061813004418#b0035.