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In the era of rapid construction and city development, cement has become an important commodity to support the continuation of the AEC sector. As a main ingredient of concrete, cement production accounts for up to 95% of concrete’s carbon footprint, subsequently granting them the position as the world's second-largest industrial emitter of carbon dioxide after the iron and steel sector. Being the main materials used in construction, the high carbon emission released by cement productions also add up to the AEC sector’s carbon footprint, making the sector responsible for 39% of global greenhouse gasses (GHG). With the rampage of insufficient housing in lots of emerging countries and hand in hand with infrastructure improvement, the construction sector will continue to reign and emit more GHG. Thus, it’s important to understand the value chain of these important AEC materials and make efforts to reduce the total carbon emission.

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In 2017, the cement industry alone is responsible for approximately 8% of the global carbon emission with a 90% carbon dioxide emission rate, meaning that for every ton of cement produced, around 900kg of CO2 is released to the atmosphere. The cement industry has been growing rapidly within the last couple of decades. From producing 1,39 billion tones of cement in 1995, it has grown to 3,3 billion tons in 2010, and an outstanding 4,1 billion tonnes in 2020, allowing for 4,4% of the industry annual growth. Globally, the cement and concrete industry accounts for 13% of the global GDP. Yet, even with this staggering amount of annual production, some countries like India are still experiencing cement shortages because between 2011-2013 alone, countries with rapid development like China have used more cement compared to the US in the entire twentieth century.

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There are two main phases in cement production. The first phase is called the hot cycle, a process where a mixture of limestone, clay, and iron ore is heated in a kiln until it reaches around 1450oC to form clinkers. Most CO2 emissions in cement production are generated in this process. Converting the limestone into clinker accounts for 60% of the emission, while the other 40% came from the combustion of the fuels in cement kilns and other processes.  The hot cycle is later followed by the cold cycle in which the clinkers are ground together with other ingredients like gypsum and chemical additives to form the final products that we know as cement. Added to the amount of carbon emitted, cement plants are all large consumers of water. For each ton of cement, the production process used around 60-130 kg of fuel depending on the type of cement produced, and 110kWh of electricity. In some countries, cement plants might also be found to use waste-derived fuel as a replacement for fossil fuel to support a circular economy and reduce their carbon footprints.

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As a highly competitive commodity with few options for diversification, cement is still a very conservative industry. Although there has been an effort of replacing clinker in cement production with other alternatives like granulated slag, fly ash, and other materials, the process of clinker formation itself is still irreplaceable. Added to that, the level of technology in cement plants is still highly volatile, depending on the country’s level of advancement. With cement having a high weight to commercial value ratio, cement is not an ideal commodity for a long supply chain and procurement route. It means that the material is almost always sold domestically, further reducing the opportunity of using a greener option produced in farther countries.

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In October 2021, The Global Cement and Concrete Association (GCCA) – an organization comprised of the leading cement and concrete manufacturers across the globe, decided to launch a ‘Global Net-Zero Roadmap’ a seven-points-plan to reduce CO2 emission by 25% in 2030 and achieve carbon neutral by 2050. The roadmap is expected to prevent up to five billion tonnes of carbon to enter the earth’s atmosphere by 2030. Cement plants and companies that failed to follow the low carbon process are at risk to face potential fines as well. The seven points of the Global Net-Zero Roadmap are as follow:

1. Savings in clinker production

2. Savings in cement and binders

3. Efficiency in concrete production

4. Carbon capture and utilization storage

5. Decarbonisations of electricity

6. Recarbonisations

7. Efficiency in design and construction

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Some major companies have tried to comply with the new roadmap plan and initiate some actions. LafargeHolcim has partnered with an American start-up company called Solid Technologies to develop concrete that could reduce the overall carbon footprint by 70%. The process would involve the different compositions of raw material and heating at a lower temperature. The concrete production process would also choose an alternative option of adding carbon dioxide instead of water. Other companies like Heidelberg Cement, CRH Plc, Ecocem, and CEMEX have also followed a similar step by reducing the use of clinker in the composition, adding other alternative ingredients, and also heating at a lower temperature.

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On the opposite side of the greener cement efforts, a Ph.D. student named David Stone has come up with a cement substitute back in 2015. He uses iron carbonate as the main ingredient for cement replacement, which creates an entirely green and carbon-negative process. Steel dust, a by-product of steel mills that is not recycled and often goes directly to the landfill is used in this process, along with silica from ground-up glass. The cement replacement has been patented as Ferrocrete and was sold as Ferrock. The ‘green cement’ is a better substitute compared to traditional cement as it was stronger and doesn’t break down when exposed to high heat or saltwater. On top of that, the resulting concrete is also flexible, allowing for crack and impact-resistant materials. Yet, with all those superior benefits, the manufacturing cost of Ferrock is still considered to be more expensive and less accessible.

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As important materials in the construction sector, the production of cement will continue to be a necessary ingredient to support the builds of safe and permanent housing, roads, bridges, or other infrastructure, and all in all, promoting economic growth all over the globe.

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