The Sustainability of Concrete: The Problems and Solutions to Its Sustainability - Sraosi Dey Upama (Mitchell High School, Eleventh Grade)

Concrete is a construction material commonly used in buildings, roads, bridges, etc. Its strength,

durability and versatility make concrete a popular material used for construction around the world.

Concrete is made from a mixture of cement, water, and aggregates; sometimes, more materials can be

added to the mixture. It is considered one of the more sustainable construction materials used in contrast

to other construction materials such as wood. However, the cement required to make concrete has shown

a significant flaw in concrete’s popular use in sustainable construction.

Portland cement is the most common type of cement used in construction. It is a powder made by

heating limestone and clay to make clinker, which is then grinded with sulfate [1]. In concrete, Portland

cement is used as an adhesive that binds with different sizes of aggregates [2]. The manufacturing process

for this cement adds to the growth of global warming in the past few years.

To form the calcium silicates and aluminates used in Portland cement, a sufficient amount of lime

is required. Lime is one of the most important ingredients to the making of cement, making up more than

half of its composition. Lime can be derived from shale and limestone [3], both of which are obtained by

mining. Mining is already known to be harmful and invasive to the environment [4]. In addition to

causing damage to the landscape and the people around it, mining limestone also releases large amounts

of greenhouse gases. The energy required to fuel the machines used for mining comes from burning fossil

fuels, releasing significant amounts of carbon dioxide into the atmosphere [5]. The process of heating

limestone to be used in cement also releases greenhouse gases. The machines used in manufacturing

concrete, such as to heat limestone and grind mixtures, contribute significantly to global carbon emissions

because they use fossil fuels as energy. As a result, the concrete manufacturing industry contributes 5% to

total global carbon emissions with cement producing over 0.81 kgs of CO2 for every kg of cement [6]. To

be more specific, Portland cement is mostly responsible for carbon emissions coming from the cement

industry, making up almost 80% of the emissions with the other 20% coming from the production of

aggregates [7].

Considering concrete is cheap and accessible, many people choose to use concrete for their

construction projects. Approximately 8 billion tons of concrete are made every year [6]. With the

information provided above, it can be estimated that almost 5 trillion kgs of carbon dioxide are released

into the air globally by the concrete manufacturing industry. However, if we can innovate cement and

concrete to accommodate lower emissions, we will be able to use these materials without sacrificing the

strength and usefulness of current unsustainable construction materials.

Hempcrete can be used as an alternative to Portland cement. Hempcrete is a bio-composite

material capable of storing carbon in its fibers [8]. Usually used as an insulator for its low conductivity, it

has a lower strength compared to other construction materials. However, its ability to store carbon in

hemp shiv and binder allows it to contribute to the minimization of carbon emissions.

Fiber cement is another alternative to Portland cement. Cement, independently, has low strength

and ductility; however, the incorporation of fibers makes it stronger and more flexible [9]. Fiber cement

can be made with biodegradable fibers like plant fiber and recycled fibers like plastics. The combination

of these fibers would be able to not only reduce future greenhouse gas emissions in the concrete

manufacturing process, but also recycle the waste created in previous years.

We are a long way from utilizing sustainable construction technology. Nevertheless, with the

responsibility of the Earth and its environments on our shoulders, it is beneficial to discover and build

more sustainable technologies that will help to mitigate the environmental risks of the construction

industry.

Bibliography:

1. Recycled Concrete. (2023). Portland Cement. Science Direct.

2. Bye, G.C. (1999). Portland Cement: Second edition. Thomas Telford Publishing.

3. TopCem. (2024). Main Ingredients in Cement and Their Functions.

4. Terrascope. (2016). Enviornmental Risks of Mining. Massachusetts Institute of Technology.

5. Yulex. (2021, November). What You Didn’t Know About Limestone Mining and the Environment.

6. Huntzinger, D.N., & Eatmon, T.D. (2009). A life-cycle assessment of Portland cement manufacturing:

comparing the traditional process with alternative technologies. Journal of Cleaner Production,

17(7).

7. Flower, D.J.M., & Sanjayan, J.G. (2007). Green house gas emissions due to concrete manufacture. Int J

Life Cycle Assess 12, 282–288.

8. Arehart, J.H., Nelson, W. S., & Srubar, W.V. (2020). On the theoretical carbon storage and carbon

sequestration potential of hempcrete. Journal of Cleaner Production, 266.

9. Balea, A., Fuente, E., Monte, M.C., Blanco, A., & Negro, C. (2021). Recycled Fibers for Sustainable

Hybrid Fiber Cement Based Material: A Review. Materials, 14(9).