Is Geopolymer Cement BETTER than Portland Cement?

June 8, 2022

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In 2020, scientists estimated that human-made materials exceeded the mass of all living things on the planet. One of these human-made culprits is Portland cement, the key ingredient in concrete that binds all the other ingredients together. Its production is very energy intensive, it causes soil erosion and noise pollution and it adversely affects air quality.

Introduction

Researchers around the world are trying to find an alternative to traditional cement and concrete that is less destructive to our planet. One very promising material is geopolymer cement. It completely replaces Portland cement with waste industrial products. It can also be much stronger and perform better than traditional concrete. In this article, we will explore how geopolymer cement compares to traditional Portland cement, its benefits, and the potential it holds for a greener future.

What is Geopolymer Cement?

The term “geopolymer” was coined by Joseph Davidovits in 1978 when he proposed a controversial theory on the construction of ancient Egyptian pyramids. According to him, these pyramids were built using a synthetic stone called geopolymer, created by pouring crushed limestone, clay, lime, and water into molds.

Inspired by Davidovits’ theory, scientists developed geopolymer cement, a 100% cement-free concrete. Instead of using Portland cement, this innovative material combines waste industrial products, minimally processed natural materials, and various waste materials that are challenging to dispose of. By repurposing these waste products, geopolymer cement significantly reduces the carbon footprint of concrete production.

How Geopolymer Cement is Made

The production of geopolymer cement involves combining waste materials such as:

Fly ash: A fine residue from coal burning power plants, rich in silicon dioxide, aluminum oxide, and calcium oxide.
Metakaolin: Created by heating china clay or kaolin to high temperatures, it finds use in tiles and traditional concrete.
Ground granulated blast furnace slag (GGBS): A by-product of the steel industry, high in calcium silicate hydrates (CSH), enhancing concrete strength and durability.
Palm oil fuel ash (POFA): Produced by burning palm oil shells and husks, this hazardous material can be converted into cement.

These raw materials undergo a chemical reaction, forming aluminosilicate gels that harden into geopolymer cement. The cement is then mixed with aggregate and water to create geopolymer concrete.

Advantages of Geopolymer Cement

Superior Strength and Durability: Geopolymers demonstrate increased strength in tension and compression, making them more resilient.
Resistance to Various Elements: Geopolymers are resistant to alkalis, salts, acids, and corrosive substances, as well as sulfur due to their unique composition.
Waterproof Properties: With pores smaller than 50 nanometers, geopolymer concrete exhibits excellent waterproofing.
Enhanced Freeze-Thaw Resistance: Geopolymer concrete can withstand temperatures over 1000 degrees Celsius (1800 degrees Fahrenheit).
Fire Resistance: Unlike Portland cement, geopolymer concrete evaporates water, preventing internal explosions during fires.
Superior Thermal Insulation: Foamed geopolymer concrete can provide exceptional thermal insulation with trapped air inside the blocks.
Reduced Carbon Footprint: Geopolymer cement significantly reduces the carbon emissions associated with concrete production.
Utilizing Waste Products: Geopolymers encourage the use of waste and by-products from existing industries, reducing the need for raw material extraction.

Disadvantages of Geopolymer Cement

Insufficient Waste Material: The global demand for cement exceeds the availability of industrial waste materials like fly ash and slag.
Variability in Waste Materials: Different waste materials have diverse chemical compositions, affecting the performance of geopolymer cement mixes.
Sensitive Production Process: The geo-polymerization process requires careful handling and specific chemical components like sodium hydroxide, which can be harmful to humans.
Competition from Portland Cement Manufacturers: Powerful Portland cement manufacturers with a concrete industry monopoly can impede the progress of geopolymer cement adoption.

Conclusion

Geopolymer cement offers a promising path towards a greener and more sustainable construction industry. With its multiple advantages, including strength, durability, reduced carbon footprint, and waste utilization, geopolymer cement is proving to be an eco-friendly alternative to Portland cement. While it may face challenges and opposition from established cement manufacturers, its potential to transform concrete production for the better makes it a viable and exciting option for a more environmentally conscious future.