Phoenix Chen

Dr. Christina Cogdell

Des 40A

May 17 2024

Taipei 101: Materials

Taipei 101, the tallest building in the world up until 2010 is a work of ingenuity and of near-indestructible design. Built to withstand massive earthquakes and the buffeting winds from tropical typhoons, the tower symbolizes Taiwan's rapid technological advancements and cultural renaissance in the 21st century. Its robust foundation is anchored deeply into the bedrock while a massive tuned mass damper in its center counteracts against swaying during high winds and seismic activities. To get a better understanding of what is behind the skyscraper’s construction,  the life cycle of Taipei 101’s main material will be analyzed through the lens of the structural steel used in all its stages, from raw materials acquisition to the final stage of waste management.

Steel, one of the major components of Taipei 101’s structure, was the material of choice for the building’s main contractor, KTRT Joint Venture. It is unclear where the steel used in Taipei 101’s construction was sourced. To narrow down the likely source of Taipei 101’s steel used by KTRT Joint Venture, China Steel Corporation, the biggest producer of steel in Taiwan, is selected to be the probable source to facilitate the duration of this analysis. The closest exact statistic on the amount of steel used is within 118,000 tonnes, a number that includes the amount of high-strength concrete used and a deep foundation system according to a paper published by the engineering firm behind Taipei 101. 

Steel is composed of iron and carbon, though other elements can be added to change its properties. A majority of iron ore, a necessary and integral material used in steelmaking, is exported by Australia and Brazil, “each having about one-third of total exports” (National Minerals Information Center). To better streamline the material acquisition and steelmaking explanation due to a lack of exact information provided by the contractor and other parties, the general manufacturing process is assumed: iron ore, coal (later converted to coke, a high-carbon fuel), and limestone (a flux agent used for the removal of impurities in the smelting process) are the primary raw materials and secondary materials. The next step, ironmaking, makes use of the blast furnace. A process called ‘reducing’ is done in the blast furnace, in which “hot air is injected into a continuous feed of coke, sinter and lime” (ArcelorMittal) to produce liquid iron, which is later transported to the basic oxygen furnace. The blast furnace process also produces two by-products, carbon dioxide (CO2) and slag (a mixture of minerals). What follows next is the steelmaking, and through the basic oxygen steelmaking method the liquid iron from the blast furnace is mixed with scrap steel, and oxygen is blown in to reduce carbon content and impurities, forming steel and slag. Afterwards, secondary steelmaking is implemented and involves the refining processes such as ladle furnace treatment for fine-tuning composition, vacuum degassing to remove gasses, and removing non-metallic inclusions for better quality. The molten steel is then poured into a continuous casting machine, where it solidifies into semi-finished shapes like billets, blooms, or slabs. They are then subsequently hot-rolled into an assortment of finished shapes such as sheets, plates, bars, or rails, with further cold-rolling at room temperature for improved finish and properties. Finishing processes include heat treatments like annealing, quenching, and tempering to achieve the desired mechanical properties and surface treatments like coating, pickling, and galvanizing are for corrosion resistance. The final dimensions and shapes are engineered through cutting, machining, and other shaping techniques. 

As there are no exact sources regarding the distribution and transportation of the steel used for Taipei 101’s construction, the widely used and assumed method would be the use of “Specialized heavy haul cargo haulers like a flatbed trailer” which is “needed to handle items with substantial length and weight, like to transport steel beams” (VeriTread). Assuming that much of the construction material is transported with cargo haulers, the fuel would be diesel. For overseas imports, cargo ships typically use heavy fuel oil. 

The transported steel will then be utilized at the construction site according to the amount the building plan calls for. There is no data regarding the planned re-use of the steel from Taipei 101 but for general demolitions, steel “Capture rates are typically above 90% and average 96%” and “For hot rolled structural sections, the capture rate is 99%” (Steel Construction). Maintenance wise, there is “a dedicated mechanical floor every eight floors, with massive floor-high steel outrigger trusses. These connect the columns in the core to the super columns on the perimeter, effectively widening the building to help it resist overturning” (Bhadeshia). For interior maintenance, those mechanical floors are likely to be where a majority of maintenance on the steel structure happens. There is no exact information on how the exterior of the building is maintained. Generally, coatings such as inorganic zinc and epoxy help prevent steel from rusting and also acts as a protective shield against moisture and erosion. 

According to the American Institute of Steel Construction, “At the end of a building's life, 98% of all structural steel is recycled back into new steel products, with no loss of its physical properties. As such, structural steel isn't just recycled but "multi-cycled," as it can be recycled over and over and over again.” Based on this statistic, it is very likely that if Taipei 101 is ever demolished or in a situation where the steel is no longer a part of its structure, demolition contractors will remove the structural steel elements to be re-fabricated for use in new structures and the “remaining steel elements are captured as scrap and used to create new steel products” (American Institute of Steel Construction). 

When steel ends up at the dump rather than building material with renewed purpose, it means that what remains was not recycled as scrap charge nor dismantled and used directly for new structures. Typically, “Only 1% of all steel that is made is lost to landfill or rust” (Galvanizers Association) and of that percentage, the treatment for steel at landfills is just like any other solid waste’s; the waste is dumped into a specific area of the landfill, compacted by a compactor, then covered with a layer of soil. The soil layer coined the ‘daily cover’ is the raw material that processes the steel although its main purpose is to simply act as a barrier between pests and the waste. 

As reflected throughout the duration of this life cycle analysis of Taipei 101’s steel, a lot of processes have to be undergone in order to get to the final product. This life cycle analysis was in no way an exact explanation for the steel’s life cycle in Taipei 101’s structure as much of its construction plans were not published but is rather a close approximation of how the material’s life cycle begins and ends in relation to the skyscraper.

The research process for specific information pertaining to the Taipei 101 skyscraper has been an arduous one. There is a lack of particulars; much of what is available on the internet do not cover a majority of the exact data for the analysis on the life cycle of Taipei 101’s steel. In order to progress with the analysis, assumptions to fill in the gaps were made, such as the explanation of the general method of transportation for construction materials in place of the exact procedure that was used for Taipei 101’s steel, which was not publicly shared. There is at the time of writing virtually no exact data on the amount of steel used, how or where Taipei 101’s steel was manufactured, processed, formulated, distributed, and transported. In order to answer all aspects of Taipei 101’s steel life cycle, the closest approximations and assumptions (based on all the life cycle aspects of steel as a construction material) were implemented to fill in the gaps to better facilitate the process. 

Bibliography

American Institute of Steel Construction. “Recycling | American Institute of Steel Construction.” Www.aisc.org, www.aisc.org/why-steel/sustainability/recycling/#:~:text=At%20the%20end%20of%20a.

Arcelor Mittal. “Making Steel | ArcelorMittal.” Corporate.arcelormittal.com, 2023, corporate.arcelormittal.com/about/making-steel#:~:text=Steel%20is%20made%20from%20iron.

Bhadeshia, H. K. D. H. “The Taipei 101 Tower, Taiwan: The Tallest Building on Earth, Made Using Steel.” Www.phase-Trans.msm.cam.ac.uk, www.phase-trans.msm.cam.ac.uk/2005/t101/t101.html#:~:text=Given%20the%20strenuous%20geographical%20circumstances%2C%20the%20engineering. Accessed 30 May 2024.

FreightCenter. “Shipping Construction and Building Materials Made Easy 7 Steps.” Www.freightcenter.com, 17 July 2023, www.freightcenter.com/shipping/building-materials/#:~:text=Materials%20on%20a%20construction%20site.

Galvanizers Association. “Steel Recycling.” Galvanizers Association, 2 Aug. 2016, galvanizing.org.uk/sustainable-construction/steel-is-sustainable/steel-recycling/#:~:text=Recycling%20steel.

International Trade Administration. Steel Imports Report: Taiwan. May 2017, pp. 1–8, legacy.trade.gov/steel/countries/pdfs/2016/annual/imports-taiwan.pdf. Accessed 31 May 2024.

National Minerals Information Center. “Iron Ore Statistics and Information | U.S. Geological Survey.” Www.usgs.gov, www.usgs.gov/centers/national-minerals-information-center/iron-ore-statistics-and-information.

Poon, Dennis, et al. Structural Design of Tai 101, the World’s Tallest Building. 2004, p. 9, global.ctbuh.org/resources/papers/download/1650-structural-design-of-taipei-101-the-worlds-tallest-building.pdf.

Reliance Foundry. “How Is Steel Made?” Reliance Foundry Co. Ltd, 2 July 2020, www.reliance-foundry.com/blog/how-is-steel-made.

S.C. Department of Health and Environmental Control. “How Landfills Work | SCDHEC.” Scdhec.gov, scdhec.gov/environment/land-and-waste-landfills/how-landfills-work#:~:text=What%20Happens%20Every%20Day.

secoaTECH. “Corrosion Resistant Coatings for Steel – Types and Uses.” Secoa Metal Finishing, 22 Nov. 2017, secoatech.com/corrosion-resistant-coatings-for-steel-types-and-uses/#:~:text=Some%20coating%20types%20that%20are.

Steel Construction. “Recycling and Reuse.” Www.steelconstruction.info, 2011, www.steelconstruction.info/Recycling_and_reuse.

VeriTread. “How to Transport Steel Beams.” VeriTread, 24 Mar. 2022, www.veritread.com/blog/transport-steel-beams/.

Jonathan Kim

Design 040A

28 May, 2024

Energy Usage in Concrete and Steel for Taipei 101

As a towering symbol and architectural marvel in engineering, Taipei 101 dominates other skyscrapers built throughout human history. Designed to withstand powerful typhoons and earthquakes, Taipei 101 embodies innovation. However, Taipei 101 took five years to construct, using a common material that covers many cityscapes: concrete and steel. Therefore, Taipei 101 consumed copious energy to create today’s modern monolith. This essay will be split into two parts, each with multiple paragraphs: concrete and steel.

Concrete’s Energy Usage in Processing Ingredients and Pumping to Structure:

 Many materials form concrete; specifically, it uses “limestone, clay, pozzolans (volcanic ash), iron ore, gypsum, [and] fly ash” (Jkcement). Cement has limestone because of “...its superior plasticity, workability, and other qualities,” which helps “...[stabilize the soil] for roads, airfields, building foundations, and earth dams, where it upgrades low quality soils into usable base and subbase materials” (Department of Energy 2). It is one of the binding agents for cement. Producing lime includes extracting, conveying, screening, secondary and tertiary crushing, and sizing, which calls for energy. Extracting limestone takes, on average, “33,500 Btu per ton” (Department of Energy 7). In cement, lime (calcium oxide) makes 60% to 65% of the mixture; therefore, if Taipei 101 used 226,821 cubic yards of concrete, which is roughly 317,549 tons of cement, the amount of limestone used is approximately 190,529 to 206,407 tons of limestone–which uses about 6,382,721,500 to 6,914,634,500 Btu of thermal energy (Topcem Cement); that is roughly 630 pounds of coal.  

Unlike other types of cement, Taipei 101 uses a special concrete that is less than water, designed by Professor Young of the National Taiwan University of Science and Technology “...by mixing cement and porous clay (obtained by dredging silt at the bottom of a dam)” (Bhadeshia). Hydraulic dredges use “submersible pumps that suck up the debris” (“Lake Dredging 101: What Is Dredging?”). Although the Internet lacks resources for finding the exact energy usage for silt dredging for Taipei 101, imagine that the contractors utilized 30-inch Cutter Suction Dredgers, commonly used in China. According to a website selling dredging equipment (dredgerbrokers.com), the main engine and four auxiliary engines, cutter head, the cantilever crane, and other consignments consume 4943 kW, which is 5,635.02 pounds of coal (for the calculations, the input cutter power is used since it consumes energy, not releases energy. Using a pound of coal as an example helps us understand the amount of heat and energy released since btu and kWh cannot intertwine since they measure different concepts: heat and energy). Furthermore, concrete also includes iron ores since it helps with “...[improving] the porosity” (Largeau). Specifically, about 0.5 to 6% of iron oxide is in concrete (Top Cem). Many iron mines are either surface mining or underground mining; most industries extract from surface mines. After extraction, the stones get crushed and screened, then ground through a less-than-325 mesh, then fed into a concentration circuit where the valuable mineral is recovered and concentrated, and finally goes through agglomeration–ores burn in a blast furnace for ironmaking by sintering, pelletizing, and briquette. “The total energy required to extract and process iron is 94,400 Btu per ton” (Department of Energy, 4 Iron 10). Thus, it takes around 5,664 Btu per ton of concrete. Therefore, Taipei 101, which used roughly 317,549 tons of concrete, used around 1,798,597,536 Btu, roughly equivalent to 90 pounds of coal burning. Gypsum in concrete allows fire resistance and sound insulation properties (Kent Companies). On average, a factory produces “...1 tonne of gypsum consumes about 20 kg of fuel oil and 28 kWh of electricity” (Bušatlić et. al. 180). If 20 kg of oil has 232.6 kWh, then 1 ton of gypsum will use 260.6 kWh. If cement “...[consist of] 3 to 5% gypsum…” (which is 0.03 to 0.05 tons of gypsum per ton of cement), then Taipei 101 called for 2,482,598.082 kWh of gypsum when constructing Taipei 101; following along with the coal reference, this is about 2,830,161.81348 pounds (since 1.14 pounds of coal is 1 kWh according to the U.S. Energy Information Administration (Mohammad, Safiullah). Ultimately, the amount of energy utilized when extracting and processing the ingredients for cement for Taipei 101 equates to using 2,836,516.83348 pounds of coal, enough to power roughly 235 houses for one year. 

Once the materials are combined and processed into cement, the factory needs to send the cement to the construction site; most cement industries utilize mixer trucks. Taipei 101’s consulting company “...worked with … Taiwan Cement Corporation…” (Schwing). According to the TCC (Taiwan Cement Corporation) factory contact information page, their cement plants are in Hoping cement plant–which takes 1 hour and 49 minutes from the construction site–, Suao cement plant–taking 1 hour and 9 minutes to the construction site–, and Hualien cement plant–taking 2 hours and 54 minutes to go back to the construction site. Although no information lists how many mixer trucks the contractors used, the company at least supplied the site with three trucks. “Ready-mix trucks burn 4 to 4-1/2 gallons per hour…” which means that all these trucks combined will use a minimum of 81 gallons to reach the site, which is about 810 pounds of coal since “...1 gallon of oil is equivalent to about 10 pounds of coal…” (Concrete Construction; MatSc 101).

Although there is no exact measurement of how much energy the construction company uses to extract, process, and integrate materials into the construction site, we can estimate the energy usage roughly. It takes about “3.4 GJ of thermal energy (in dry process) and 110 kWh of electrical energy…” to produce one ton of cement (Mohktar and Mohsen). Therefore, if Taipei 101 used 226,821 cubic yards of concrete, which is roughly 317,549 tons of cement, then it took about 1,071,667 GJ of thermal energy and 34,931,100.5 kWh of electrical energy, which is enough to power almost 9,800 houses annually. Combining the energy used for gathering ingredients and implementing it in Taipei 101 via construction vehicles can almost power 10,035 houses (9,800 annually and 235 for a year).

However, imagine a natural disaster destroys the building or some bulldozers decide to decimate the fundamental tower. Concrete gets recycled by breaking it up with a portable crusher at the job site, removing unwanted materials like dirt and steel, and crushing the remaining mixture into preferred spaces at quarry sites; this mixture is called Recycled Concrete Aggregate (RCA). “The energy used in the production of crushed aggregate is 82 kJ/kg, and … the energy required for the transportation of material for every 100 km is 265.5 kJ/kg” (Hameed and Chinini 3). If the recyclers collected 288,075,607 kg of concrete from Taipei 101, they would use 23,622,199,774 kJ to produce crushed aggregate. According to the CTCI E-Newsletter, TCC’s Renewable Resource Recycling Center (RRRC) is located at Heping Cement Plant in Hualien County; thus, the distance will be around 113 km, 300.015 kJ. The calculations only include one trip since there are scarce resources in Taiwan’s concrete recycling management. 

Steel’s Energy Usage in Processing Ingredients and Implementing to the Structure:

Another essential asset for Taipei 101’s creation is steel. Taipei 101’s frame “...required 107,000 Mg (118,000 tons) of steel members and connections...” (Poon et al.). Steel starts from iron–where stated before, used 94,400 Btu/ton in extraction through surface mining. Steel manufacturing is an energy-intensive process since “traditional steel furnaces burn [iron with] fossil fuels to reach the temperatures needed to smelt raw iron and carbon into steel” (Office of Energy Efficiency & Renewable Energy). During the emission process, factories use carbon to remove oxygen from the iron ores, reducing it to pig iron–essential for steelmaking. After, the basic oxygen furnace (BOF) then converts iron to steel and gets cast, rolled, and/or coated into strips, plates, sections, or bars. In a Basic Oxygen Furnace, “oxygen is blown through liquid pig iron, increasing its temperature and releasing carbon. Pure oxygen is used as it improves the efficiency of the reaction between carbon and oxygen” (Martelino). However, “...the production of hot metal or pig iron is the most energy intensive process for steel production at roughly 13.5 × 109 joules per ton (1000 Kg) of pig iron produced. The basic oxygen furnace is the second most energy intensive process at 11 × 109 joules per ton or steel produced” which is roughly 3,750.3 kWh produced and 3,305.82 kWh with a BOF–enough to power a house for 110 to 125 days, which is around 30% of the year (Martelino). 

Realistically, Taipei 101’s contractor may have contacted the most significant domestic steel group of EAF-integrated steelmaking: the Taiwan Steel Group. In addition, most of their steel–even though no sources are stating where Taipei 101’s company supplies their steel–is imported mainly from China and Japan; “Taiwan imported the largest share of flat products from Japan [...] at 43 percent (760 thousand metric tons), followed by China at 27 percent (481 thousand metric tons)” which means 70% of steel are from these two exporters (International Trade Administration 4). Therefore, these companies would use many cargo ships to export to Taiwan. Hypothetically, if China and Japan had at least three average cargo ships sending steel, with “...engines have been designed for top speeds ranging between 20 and 25 knots per hour, which is between 23 and 28 miles per hour. [Then], a Panamax container ship can consume 63,000 gallons of marine fuel per day at that speed” (FreightWaves). If it takes a day to travel from China and Japan to Taiwan, then to travel from the steel plant to the construction site via ship, it would take 378,000 gallons of marine fuel (marine fuel is a type of fuel oil); that is 4,951,800 pounds of coal or 4,357,584 kWh, which can fuel 403.48 American houses for a year. The hypothetical situation mentioned does not include the energy used to return to their plants. Therefore, using 378,000 gallons of fuel is just the minimum for bringing steel to Taipei 101. 

Imagine the theoretical situation mentioned above, but instead of focusing on concrete, the scenario shifts to steel. After a terrible disaster struck Taipei, leaving Taipei 101 in ruins, the steel may get recycled. Unlike “the production of steel from virgin iron ore (primary steel) [which] requires a number of energy-intensive steps with a cumulative energy input of 15–24 GJ/t, much of it as coal, while the melting of pure scrap steel to produce new steel (recycled or secondary steel) requires only 1.3–6.0 GJ/t, all of which can be supplied by electricity that in turn can be produced from renewable energy sources” (Harvey 1). According to Harvey, when producing liquid steel from BOF (Blast Oxygen Furnace) and EAF (Electric Arc Furnace), the output of blast furnaces from creating useable iron ores (in the forms of lumps, pellets, or sinter) is pig iron, and contains metal oxide which is removable through oxidation; this process creates slag, the waste material. “Three kinds of scrap are generated during the lifecycle of steel” forming scrap, which is produced during the casting and shaping of intermediate steel products such as rods, tubes and sheets; fabrication scrap, which is generated when intermediate product are cut into final products; and end-of-life (EOL) scrap, which is produced when steel products are no longer used” (Harvey 2). In this example, I will focus on the EOL scrap since Taipei 101 in the scenario has reached its end of life; therefore, when recycling EOL scraps, “...some non-steel contaminants (such as plastic, copper wire, or aluminum) are generally mixed in small quantities with the steel due to imperfect separation of different materials prior to melting” (the EOL scraps contains different alloys, which can cause inconsistencies in its composition) (Harvey 2). Sometimes, the firm removes impurities in the mix by vaporizing or removing slag when refining, and thus, pig iron or direct reuse iron must be added to the scraps to dilute the impurities. “Recycling steel saves 72% of the energy needed for primary production (i.e., 4,697 kWh per tonne)” (EuRIC 4). Therefore, the whole recycling process consumes “...6-15 MJ (1,655 to 4,170 Wh)” to produce 1 kg of recycled steel (Decker). Recycling all the steel frames in Taipei 101 will call for 642.28698 TJ to 1,605.71745 TJ; to comprehend how much power this is, this is roughly 10.195 atomic bombs to 25.488 atomic bombs released onto Hiroshima.

Conclusion:

Taipei 101 demands a lot of energy usage, excluding other materials besides concrete and steel during its construction. Although many glorify sustainability and innovation now, the energy requirement of acquiring materials, processing them, distributing them, and possible waste disposal requires high energy consumption. For concrete, it took at least 34,931,100.5 kWh and 1,071,667 GJ of heat–roughly equivalent to powering 10,035 houses (9,800 annually and 235 for a year). It will take a minimum of 4,360,889.82 kWh for the steel frames to produce and distribute steel and use around 1,605.717 TJ to recycle steel. This is enough to power many homes for years and enough heat to decimate a whole country––almost hot as the sun. In addition, Taiwan companies continue to look for more sustainable options for future projects like using recycled steel. 

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