The production of cement has a significant carbon footprint, but green cement has emerged as an environmentally friendly alternative. To minimize the carbon footprint of cement production, many innovative approaches have been developed, resulting in the production of several types of green cement.
Green cement is produced using energy-efficient and low-carbon methods, as well as new cement formulations, geopolymers, carbon-negative cements, and new concrete products. By incorporating discarded industrial waste such as blast furnace slag and fly ash, green cement production can also reduce cement consumption.
Several types of green cement have been developed, including Ekkomaxx cement, magnesium oxychloride cement, geopolymer cement, ferrocrete, calcium sulfoaluminate cement, and sequestrated carbon cement. While some of these cements have been commercialized and used in various construction projects, others have yet to be widely utilized. However, these cements hold great potential for future use in construction projects.
Types of Green Cement
1. Ekkomaxx Cement
Ceratech, a company based in the United States, has developed a unique type of green cement known as Ekkomax. This cement is made up of 95% fly ash, a waste product generated from burning coal, and 5% renewable liquid additives. According to industry standards such as the International Code Council and United States Green Building Council, Ekkomax has an almost negligible carbon footprint.
The production of Ekkomax cement has several benefits over traditional cement. It reduces the use of virgin materials by 95% and reduces water requirements by half. Additionally, this cement exhibits exceptional qualities such as high early strength, resilience, crack resistance, low chloride permeability, and resistance to sulphate attack. It also has excellent durability and corrosion resistance, which is three times higher than that of conventional cement. Furthermore, Ekkomax has greater resistance to freezing and thawing compared to ordinary cement.
2. Magnesium Oxychloride Cement
Magnesium Oxychloride Cement (MOC) is a type of cement that is eco-friendly and has a carbon-neutral production process. It is made by combining magnesium oxide (MgO) powder and a concentrated solution of magnesium chloride (MgCl2), which are byproducts from magnesium mining. This cement is known for its high compressive strength and quick setting time. Additionally, MgO is able to absorb carbon dioxide from the atmosphere.
However, MOC’s strength can be significantly reduced when it comes into contact with water. This issue can be addressed by adding fly ash and silica fume. These additives help to fill the pores in MOC, making the concrete denser and improving both its strength and durability. To further improve the resistance of MOC against warm water, phosphoric acid and soluble phosphates must be added.
It is important to note that MOC can cause corrosion of steel. As a result, it cannot be used in construction for reinforced concrete structures unless this problem is addressed.
3. Geopolymer cement
Geopolymer, which is also known as alkali-activated cement, is produced from aluminosilicates instead of the more environmentally damaging calcium oxide.
The aluminosilicates are obtained from industrial by-product like fly ash. The geopolymer cement is competitive with ordinary Portland cement in performance and cost, and it emits 95% less CO2 than the ordinary Portland cement.
3. Ferrocrete
Ferrocrete cement is a novel material created by researchers at the University of Arizona. It is made by blending waste byproducts, specifically silica and iron, from the steel and glass industries. The mixture is then cured using carbon dioxide, which has the potential to transform the material into a carbon-negative substance.
4. Calcium Sulfoaluminate Cement
Calcium sulfoaluminate cement is a type of cement that can be produced at a lower temperature than conventional cement. This is because it only requires a kiln temperature of 1232.2C (2250F) rather than the 1426.6C (2500F) temperature needed for traditional cement. As a result, the production of this cement emits less CO2 into the atmosphere, which is beneficial for the environment.
One of the unique properties of calcium sulfoaluminate cement is its rapid setting time. It can achieve the same strength as conventional concrete in just 24 hours, which is a significant advantage in projects where rapid setting is crucial, such as for bridge decks and airport runways.
Calcium sulfoaluminate cement can also be used as a shrinkage compensating cement by adding a higher quantity of gypsum. This further enhances its usefulness in construction projects.
Another advantage of this type of cement is that it can achieve energy savings of up to 25% compared to Portland cement. Additionally, its use results in a reduction of CO2 emissions by around 20%. This makes calcium sulfoaluminate cement a more sustainable and environmentally-friendly option for construction projects.
5. Sequestrated Carbon Cement
Calera Corp. in California has developed a new method for producing cement using seawater or brine mixed with carbon dioxide. This innovative cement production process involves filtering CO2-rich gases through seawater, which results in the extraction of calcium and magnesium from the seawater. These extracted elements then react with CO2 to create a high-quality cement product that can be used as a substitute for Portland cement.
One of the major advantages of this new method is that it produces a white, air-permeable cement that is stronger than regular OPC. Additionally, the use of seawater and brine as a base material for cement production is a sustainable solution that reduces the reliance on traditional cement manufacturing methods.
Overall, the Calera Corp. cement production process represents a promising development in the field of sustainable construction materials. By leveraging the unique properties of seawater and CO2, this method has the potential to revolutionize the cement industry and provide a more eco-friendly alternative to traditional cement production.
6. Cement Produced Using Superheated Steam
Superheated steam is a technique that can be employed to enhance the reactivity of cement particles. During this process, the cement particles are subjected to high temperatures in the presence of steam, which causes them to undergo chemical and physical changes that make them more reactive.
However, the process of superheated steam also leads to the emission of CO2. This is a significant concern, as CO2 is a greenhouse gas that contributes to climate change. In order to mitigate the environmental impact of this process, it is necessary to capture and separate the emitted CO2.
Capturing the CO2 emitted during the superheated steam process can be challenging, but it is an important step towards reducing the carbon footprint of cement production. Once the CO2 has been captured, it can be stored or repurposed for other industrial applications. This approach can help to reduce the overall emissions associated with cement production, which is a major contributor to greenhouse gas emissions globally.
7. Cement Produced with Reactive Hydrothermal Liquid-phase Densification
There exists a type of cement that is manufactured using the same raw materials as regular Portland cement. However, it is produced at a lower temperature and undergoes different chemical reactions that result in the emission of less carbon dioxide, in contrast to the conventional Portland cement production process.
To create this cement, it is mixed with water and CO2, and as a result of the reaction with CO2, it produces calcium carbonate and silica. This eventually hardens, leading to the formation of concrete. Solidia Technology Company, located in the United States, is responsible for the creation of this environmentally friendly cement. The company has partnered with Lafarge to further develop and commercialize the technology for cement production.
Advantages
Green cement is a sustainable alternative to traditional cement, as it emits significantly less carbon dioxide during its production. In fact, it can release up to 80% less carbon dioxide, making it a much more environmentally friendly option. This is due to the fact that green cement requires less heat during production, which reduces the amount of carbon dioxide released into the atmosphere.
One of the benefits of using green cement is that it makes use of industrial waste such as fly ash, silica fume, and last furnace slag. These by-products are often difficult and costly to dispose of and can take up several acres of land. By using them in green cement production, land is protected from becoming a dumping ground and ultimately being destroyed.
Another advantage of green cement is that it requires less energy to produce. This is because industrial by-products are present in the cement mixture, reducing the amount of energy needed for production. Additionally, green cement is known for its ability to withstand temperature fluctuations, which decreases the costs associated with heating and cooling. Overall, the use of green cement is a more sustainable and cost-effective option for construction projects.