Examining the Environmental Costs of Geopolymer mortars

October 2nd 2023 in Sustainability
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Introduction

Geopolymer mortar has garnered attention as an alternative to traditional cement masonry mortar due to its potential environmental benefits. Proponents of geopolymers highlight their low carbon footprint and use of industrial by-products.

However, it's crucial to take a closer look at the full life cycle of geopolymer mortar, including the environmental costs of its early life cycle, often obscured by its proponents.

The Geopolymer Advantage

Geopolymer mortar is primarily touted for its lower carbon footprint compared to cement-based counterparts. This lower carbon footprint is attributed to the use of geopolymers, which are typically composed of industrial by-products such as fly ash and slag. Advocates emphasize the reduction of carbon dioxide emissions that result from utilising these waste materials.

Unveiling the Environmental Costs

While the use of industrial by-products seems environmentally friendly on the surface, it's essential to consider the hidden environmental costs associated with their initial processing. These costs are often neglected or understated:

1. Extraction & Processing

Fly Ash

Extraction: Fly ash, a common geopolymer precursor, is generated as a by-product of coal combustion. The extraction and combustion of coal are associated with various environmental issues, including habitat destruction, water pollution, and greenhouse gas emissions.

Transportation: Fly ash must be transported to processing facilities, often over long distances, contributing to energy consumption and emissions.

Slag

Production: Slag, another geopolymer component, is obtained during the smelting of iron ore. This process involves significant energy consumption and greenhouse gas emissions.

Resource Depletion: Iron ore mining depletes natural resources and causes habitat disruption.

2. Energy Intensity

The manufacturing of geopolymers requires high-temperature curing processes, which demand substantial energy inputs. This energy is typically derived from fossil fuels, further contributing to carbon emissions.

3. Chemical Considerations

Geopolymer production involves the use of alkaline activators, often sodium hydroxide or potassium hydroxide. The production and disposal of these chemicals can have adverse environmental impacts.

4. Longevity and Durability

While geopolymers may offer good durability and resistance to corrosion, their long-term performance is not yet fully understood. Premature deterioration or replacement may negate any initial environmental benefits.

Conclusion

While geopolymer mortar is marketed as an environmentally friendly alternative to cement masonry mortar due to its use of industrial by-products and low carbon footprint, it's vital to scrutinise the full life cycle of this material. 

The environmental costs associated with the extraction, production and transportation of geopolymer precursors, as well as the energy-intensive curing processes and chemical considerations, cast doubt on its overall sustainability.

Acknowledging these environmental costs is essential when evaluating geopolymer mortar as a viable option. 

To make informed decisions about its use, builders and architects must weigh the potential benefits against the hidden environmental drawbacks. 

Further research and transparency in reporting are necessary to fully understand the environmental impact of geopolymer mortar and its role in sustainable construction.

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