Cement is the most popular binder used in construction to harden and set other materials. Mostly it’s used to bind products together, such as gravel and sand. Innovative technologies have made green cement a better and much more sustainable alternative to regular cement.
In this article we cover why and how green cement can be one of the solutions to reduce emissions in construction. We’ll also talk about the types of greem cement and its producers, as well as the scope and potential of green cement adoption.
After water, concrete is the most consumed resource in existence. The annual production of cement increases every year and is likely to surpass 5 million metric tons a year by the end of 2050. This is not a surprise, considering how widely cement production happens.
The annual production level of OPC; Ordinary Portland Cement is almost 3.6 billion metric tons. Columbia university’s earth institute states that the annual growth rate of cement manufacturing is 2.5%.
Every year the cement manufacturing industry produces 2.55 billion tons of cement. We know for sure that there is a lot of cement in the environment, and it’s not promoting a healthy atmosphere.
Why is The Cement Manufacturing Process Not Environmentally Friendly?
The manufacturing procedure of cement is not as environmentally friendly as it might seem. In the process, a mix of clay soil and limestone is subjected to a temperature of 1400 degrees Celsius in the kiln. Then after the thermal process, the material is crushed to form a clinker (a thick substance). Then gypsum is mixed in the clinker, which leads to cement formation.
A large amount of toxic gasses is released during the production of clinker. For every metric ton of cement produced, 0.6 to 1 ton of carbon is released into the atmosphere, leading to air pollution.
Green Cement is the Solution
Even knowing that cement manufacturing causes a large amount of air pollution, the process cannot be stopped. It would be absurd to think of a world without cement in it.
The only alternative available at this time is green cement. It has the potential to cut down the emissions generated in the conventional manufacturing process of cement.
When cement is manufactured with the help of a carbon-negative production process, then it is known as green cement. Thus, it helps minimize carbon footprint and other environmental issues during cement production.
The green variety of the binding can help remedy serious industrial pollution and help society live sustainably.
Cement has 0.5 to 0.6 % of iron dioxide present, which provides strength to the hardness and color of the cement. This cement dries out faster and has a lower rate of shrinkage. It lasts longer and makes for a perfectly sustainable product for the environment.
Many nations recognize the importance of green cement by virtue of international symposiums raising awareness about climate change. Multiple technologies for the manufacturing of green cement are already available and have been patented by different companies.
However, today it’s important to spread awareness about green cement. Consumers and manufacturers often consider investing in such innovative production technology risky from a financial standpoint.
Ideally, national governments should support green cement production to meet construction requirements in an eco-friendly manner.
Investors in manufacturing companies should get incentives for the adoption of green cement production process. Home inspectors can help keep records of constructions made from green cement and reward the builder.
But if we want to see a global effect of reducing carbon dioxide emissions, we all need to include green cement in construction.
Green cement manufacturing requires less natural materials. That’s the reason very less carbon dioxide is released into the atmosphere during the process and it doesn’t let the land become a dumping ground for toxic waste.
The process involved in producing conventional cement required a vast amount of natural gas for heating purposes. As green cement already has an industrial by-product, energy emission is significantly reduced. Let’s look at the benefits of using green cement on a large scale.
- Extended Life Expectancy:
Compared to other conventional cement, green cement offers fire resistance and takes a great setting time. Structures built from green cement have a longer life span.
- Low Carbon Emissions:
The manufacturing process of green cement follows advanced techniques that can reduce carbon emissions by up to 80%, causing less pollution.
- Energy Conservation:
Emissions of less carbon in the environment mean less heat energy is required in the production process.
- Industrial Waste Utilization:
The production of green cement calls for the use of by-products, such as fly ash silica, blast furnace slag, iron, which is both economical and reduces the amount of disposed waste.
Types of Green Cement
There are multiple types of green cement that differ depending on the technology used to make them.
- Calcium Sulfoaluminate Cement
Calcium sulfate aluminate cement needs lesser temperatures than conventional cement, and hence it reduces the energy consumption by 25%. This also leads to a 20% decrease in carbon emissions. As the cement setting time is quick, it can attain the strength of 28 days in just 24 hours. The cement is best used for airport runways and bridge deck constructions.
- Geopolymer Cement
This type of cement is manufactured from aluminum silicates produced from fly ash. It is called alkali-activated cement and produces 95% less CO2 compared to ordinary Portland cement. Geopolymer is somewhat like ordinary cement in terms of performance and cost. This is the greenest cement of all.
- Sequestrated Carbon Cement
Calera Corp. cement in California reduced the emissions of its cement using brine compounded with CO2 and seawater. This cement is a perfect alternative for Portland cement.
- Ekkomaxx Cement
Ceratech Company from the United States developed Ekkomaxx Cement. It has 5% renewable liquid additives and 95% fly ash. The International Code Council and US Green Building Council standards have found this cement to have a zero carbon footprint. Ekkomaxx cement has high resilience, strength, sulfate attack resistance, crack resistance, and corrosion resistance.
Scientists at the University of Arizona invented this cement using byproducts of the glass and steel industry, mostly iron and silica. A blend of these materials is cured in the presence of CO2, and thus, a carbon-negative cement material is obtained.
- Magnesium Oxychloride Cement
This is produced from magnesium mining byproducts called magnesium oxide powder and concentrated magnesium chloride solution. This carbon neutral and eco-friendly cement has a high compressive strength and quick setting time.
Water can decrease the strength of MOC, which can be managed to a certain extent by incorporating additives like fly ash. However, this cement is not meant to be used for reinforced concrete work, as it can cause steel corrosion.
While there are so many manufacturers out there, let’s look at the three prominent companies producing the purest form of green cement.
Calix designs open and standards-based platforms that work rapidly with the latest cutting-edge technologies.
CarbiCrete’s concrete manufacturing procedure is quite similar to conventional concrete with a few important differences. Instead of mixing cement with water and aggregate, in CarbiCrete’s process, steel slag is used as the primary substance mix.
The mix is then put into a conventional block-making machine which forms CMUs. And to cure the concrete, it is placed into a specialized absorption chamber along with injected CO2. Within 24 hours, the concrete reaches its full strength.
- CarbonCure Technologies
CarbonCure manufactures innovative CO2 removal technologies for every size of concrete producers. In this process, a specific dosage of captured carbon dioxide is injected into concrete during mixing for mineralization. This increases the concrete’s compressive strength, enabling significant carbon footprint reductions along with cost saving.
Scope of Green Cement
Incorporating green cement in construction instead of conventional cement would be a major step toward mitigating the climate crisis and preserving the environment. The primary raw materials used to make the more sustainable alternative are fly ash, blast furnace slag, and other similar industrial waste.
It has attractive parameters such as higher ductility and long-term strength. During the manufacturing process, carbon emissions are significantly reduced. The total reduction of its carbon footprint is by 40%.
Besides reducing carbon dioxide emissions, the manufacturing process of green cement also helps maintain cement strength. Green cement has powdered limestone calcined clay, enhancing mechanical strength and reducing porosity.
Green taxes can be levied on conventionally produced cement giving rise to OPC prices twofold. Therefore, green cement offers excellent potential for the future, both in terms of quality and price benefits, as well as environmental advantages.