Environmental pollution has become a major concern globally, especially in India. Construction activities, particularly the use of concrete mixes, serve as a major contributor to pollution. This is where geopolymer concrete comes in. With its eco-friendly nature, geopolymer concrete sets itself apart from cement or regular concrete. Read on to learn about geopolymer concrete and its benefits.
See also: What is Green Concrete?
What is geopolymer concrete?
Geopolymer concrete has emerged as an environmentally friendly substitute for traditional cement concrete. Crafted by blending industrial by-products like fly ash and ground granulated blast furnace slag (GGBS), it champions sustainable construction practices. Fly ash, a by-product from thermal power plants, and ground granulated blast furnace slag, generated in steel plants, form the core ingredients. Geopolymers primarily derive silicon and aluminium from thermally activated natural materials (e.g., kaolinite) or industrial by-products (e.g., fly ash or slag). An alkaline activating solution polymerises these materials into molecular chains and networks, resulting in a durable binder. Also known as alkali-activated cement or inorganic polymer cement, its adoption aids waste reduction and diminishes carbon emissions by mitigating the demand for Portland cement.
Geopolymer concrete: Composition
To produce geopolymer concrete, the following materials are essential:
- Fly ash: A byproduct obtained from thermal power plants.
- GGBS: A byproduct derived from steel plants.
- Coarse aggregates and fine aggregates: Essential components similar to those used in conventional concrete.
- Alkaline activator solution for GPCC: This solution, serving as an activator for geopolymer concrete, comprises alkali silicates and hydroxides dissolved in distilled water. A catalytic liquid system is commonly employed for this purpose. The alkaline activator solution plays a pivotal role in activating the source materials rich in silicon and aluminium, such as fly ash and GGBS.
Geopolymer concrete: Properties
Geopolymer concrete exhibits several noteworthy properties:
- Compressive strength: Geopolymer concrete demonstrates impressive compressive strength, reaching up to 70 MPa (N/mm²). It attains this strength rapidly, surpassing the early strength development of ordinary Portland cement concrete. After 24 hours, the concrete’s compressive strength exceeds 25 MPa, while after 28 days, it ranges between 60 and 70 MPa.
- Drying shrinkage: Geopolymer concrete experiences significantly less drying shrinkage compared to traditional cement concrete. This characteristic makes it particularly suitable for thick and heavily restrained structural members.
- Heat of hydration: Geopolymer concrete exhibits a lower heat of hydration in comparison to cement concrete.
- Fire resistance: The fire resistance of geopolymer concrete is considerably superior to that of Ordinary Portland Cement (OPC)-based concrete.
- Chloride permeability: Geopolymer concrete boasts a ‘low’ to ‘very low’ chloride permeability rating according to ASTM C1202. This attribute provides enhanced protection to reinforcement steel, reducing the risk of corrosion as compared to traditional cement concrete.
- Acid resistance: When subjected to exposure to 2% and 10% sulphuric acids, geopolymer concrete demonstrates very high acid resistance, making it resilient in corrosive environments.
- Initial rate of absorption (IRA): Geopolymer concrete is known for its better IRA range as compared to regular concrete.
Geopolymer concrete: Applications
Geopolymer concrete finds versatile applications in the construction industry, offering unique benefits for various projects. Here are key areas where geopolymer concrete is applied:
- Infrastructure projects: Bridges, tunnels and highways benefit from the high strength and durability of geopolymer concrete, ensuring longevity and structural integrity.
- Residential construction: Geopolymer concrete is used in residential projects, particularly for walls, foundations, and floors. Its low carbon footprint and excellent thermal properties contribute to energy-efficient homes.
- Industrial buildings: Industrial structures, including factories and warehouses, leverage geopolymer concrete for flooring and structural components. Its resistance to chemicals and abrasion suits heavy-duty industrial applications.
- Marine and coastal structures: The resistance of geopolymer concrete to corrosion and seawater makes it an excellent choice for coastal and marine projects such as jetties, seawalls, and offshore platforms, ensuring durability in harsh environments.
- Sustainable construction: Geopolymer concrete aligns with the principles of sustainable construction by significantly reducing carbon dioxide emissions during production. This makes it an environmentally friendly choice for construction projects, contributing to a lower overall environmental impact.
Geopolymer concrete: Advantages
Geopolymer concrete presents several advantages, making it a preferred choice in the construction industry:
- Strength and durability: Geopolymer concrete exhibits superior strength and durability compared to conventional concrete. Its elevated compressive strength enables it to withstand heavy loads and resist cracking, making it ideal for long-lasting structures.
- Environmental friendliness: Manufactured from industrial by-products like fly ash, geopolymer concrete reduces reliance on natural resources, such as limestone. This eco-friendly approach minimises carbon emissions, contributing to a more sustainable and environmentally conscious construction industry.
- Fire and chemical resistance: Geopolymer concrete demonstrates excellent fire resistance, maintaining structural integrity even at high temperatures. Additionally, its high resistance to chemical attacks makes it suitable for areas exposed to corrosive substances.
- Cost-effectiveness: Despite a slightly higher initial cost compared to traditional concrete, geopolymer concrete offers long-term cost savings. Its enhanced durability reduces the need for frequent repairs and maintenance, resulting in overall lower costs over the structure’s lifespan.
- Reduced carbon footprint: Geopolymer concrete significantly lowers the carbon footprint in contrast to regular concrete. Utilising industrial by-products helps in waste reduction and conservation of natural resources, aligning with sustainable practices in construction.
Geopolymer concrete: Disadvantages
While geopolymer concrete offers numerous benefits, it is essential to consider its drawbacks:
- Limited availability: Geopolymer concrete is not widely accessible in the Indian market. Currently, only a few manufacturers produce it, potentially restricting its availability for construction projects.
- Higher initial cost: In comparison to traditional concrete, geopolymer concrete may have a higher initial cost. This is attributed to the expenses associated with raw materials and specialised manufacturing processes. However, the long-term benefits and durability of geopolymer concrete should be taken into account.
- Lack of standardised codes and guidelines: Being a relatively new technology, there is a lack of standardised codes and guidelines for the design and construction of geopolymer concrete. This can pose challenges for engineers and contractors looking to incorporate geopolymer concrete in their projects.
- Limited research and development: Geopolymer concrete has undergone less research and development compared to traditional concrete. As a result, uncertainties may exist regarding its long-term performance, durability, and resistance to environmental factors. Further research is necessary to address these concerns.
- Limited awareness and acceptance: Geopolymer concrete remains relatively unfamiliar to many construction professionals and clients. This lack of awareness and acceptance could impede its widespread adoption. Educational and promotional efforts are crucial to enhance awareness and foster trust in geopolymer concrete.
FAQs
What is geopolymer concrete?
Geopolymer concrete is an eco-friendly substitute for traditional cement concrete, crafted by blending industrial by-products like fly ash and ground granulated blast furnace slag (GGBS). It is activated with an alkaline solution, creating a durable binder. This sustainable alternative reduces waste and minimises carbon emissions, contributing to environmentally conscious construction practices.
Are there any notable projects that have used geopolymer concrete?
Yes, notable projects utilising geopolymer concrete include the Delhi Metro project, road construction in parts of Telangana, and the construction of The University of Queensland’s Global Change Institute (GCI).
What is geopolymer concrete made from?
Geopolymer concrete comprises industrial by-products such as fly ash and GGBS, serving as the primary ingredients. Additionally, it includes coarse and fine aggregates similar to those in traditional concrete. The activation of geopolymeric source materials rich in silicon and aluminium is achieved through an alkaline activator solution, commonly using a catalytic liquid system.
What properties make geopolymer concrete stand out?
Geopolymer concrete exhibits impressive compressive strength, minimal drying shrinkage, low heat of hydration and superior fire resistance. It also demonstrates 'low' to 'very low' chloride permeability, providing enhanced protection against corrosion. Its acid resistance, initial rate of absorption (IRA), and durability make it a standout construction material.
Where is geopolymer concrete used?
Geopolymer concrete finds applications in various construction projects, including infrastructure such as bridges and tunnels, residential construction for walls and foundations, industrial buildings, and coastal structures like seawalls.
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