Is Low Or Zero-Carbon Cement The Upcoming Trend?

Rony

Moderator
Cement plays a crucial role in our daily lives. It is a major component of concrete and the second most consumed product worldwide, after potable water. Houses, dams, staircases, dikes, factories, and virtually every construction you see is built using cement.
Although cement is an important material for building and construction, the cement industry is one of the major contributors to CO2 emissions – around 8% of manmade CO2 emissions. According to an estimate of cement production, almost 6 billion tons of cement were produced globally.

During concrete formation, cement acts as the binder between aggregates (fine and coarse rocks). In this mixture, cement makes up approximately 12% by volume which is almost solely responsible for the resulting CO2 emissions.
Traditionally, cement is made using various raw materials, including limestone (calcium carbonate), which are heated in a kiln in a process known as pyroporcessing. The result of this fuel-intensive process is the so-called clinker.
Clinker comprises small lumps of stony residue that are ground to a powder and mixed with other ingredients to produce cement. In the process, the calcium carbonate (CaCO3) is converted into calcium oxide (CaO), releasing large quantities of carbon dioxide (CO2) into the atmosphere.

Cement Alternatives​

You already know that CO2 is a greenhouse gas but abatement pressures could prompt the cement industry to embrace the upcoming trend, which is to reimagine the business. For several years, scientists, government, cement manufacturers, and researchers have been looking for cement alternatives to promote low or zero-carbon cement production as the consequences of climate change become more apparent.
Soon, we hope to see houses, bridges, cityscapes, and dams built with low or zero-carbon cement. Several options are been looked into in an attempt to decarbonize cement. Analysts predict that by 2050, CO2 could be reduced by 75%. However, technological innovations could facilitate 80% while the remainder will come from operational advances. With over 77 countries committed to decarbonizing cement by 2050, achieving this goal looks feasible.
Calcium sulphoaluminate cement is among the upcoming trends and a potential solution. Calcium sulphoaluminate cement is formed when a large portion of the limestone is replaced by bauxite. Some researchers at the Martin Luther University Halle-Wittenberg (MLU) in Germany have collaborated with fellow researchers at the Brazilian University of Pará to develop a climate-friendly alternative to conventional cement.
This alternative can reduce carbon dioxide emissions by up to 2/3rd during production when unused bauxite is used as a raw material. But while this will decarbonizes cement, sourcing the raw material is a big deal. Bauxite is not available in abundance and even if it is, it is a Holy Grail material in aluminium production.

The Quest to Find Zero-carbon Cement​

Cement companies are not relenting in their quest to finding low or zero-carbon cement. Discovering Belterra clay might be a huge success for cement suppliers. In the cement-manufacturing process, calcium carbonate cannot be entirely replaced, at least not yet, due to its nature and characteristics in cement production. At the very least, around 60% of the limestone can be replaced with an alternative option.
Since pure bauxite is not abundant in nature, utilizing it as a solution can only be in the short term. With an overburden such as Belterra clay, we might be edging closer to decarbonizing cement. Belterra clay can be up to 30 meters thick and is abundant in nature, unlike the bauxite deposits.
It can be found in the Amazon basin and other tropical regions of the earth. Belterra clay’s abundance in nature makes it readily available in large quantities. It contains essential minerals and particles of aluminium that guarantee good quality cement without additional treatment.
Another advantage of the Belterra clay is that the burning process requires 392° Fahrenheit (200° Celsius) less than what is required when producing conventional cement. This means that less CO2 will be released during the chemical conversion up to 65% during conventional cement production.

The Bottom Line​

With Covid-19 ravaging across almost all industries, the effort to decarbonize cement might be met with some serious challenges. Nonetheless, researchers suggest that by 2050, the cement industry could reduce its 2017-level emissions by more than three-quarters.
This is a piece of good news, and cement manufacturers are definitely looking forward to more sustainability in building materials and the construction industry.
 
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