Geopolymer concrete is made from fly ash and an alkaline solution, combining waste products into a useful material. Its setting mechanism depends on polymerization and it cures between 60-90 degrees Celsius. It is made by mixing fly ash aggregates with an alkaline activator solution of sodium or potassium hydroxide and silicate. The fresh concrete can be worked with for up to 120 minutes before setting and does not lose strength. It offers advantages over traditional concrete like lower carbon emissions, better strength and fire resistance, and excellent properties in acid and salt environments.
9. The aggregates are prepared in saturated-surface-dry (SSD) condition, and are kept in plastic buckets with lid Dry Materials of Geopolymer Concrete
10. The fly ash and the aggregates are first mixed together dry in 80-litre capacity pan mixer . Pan Mixer Used in the Manufacture of Geopolymer Concrete
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13. The workability of the fresh concrete was measured by means of the conventional slump test Slump Measurement of Fresh Geopolymer Concrete
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Notes de l'éditeur
So if the properties are comparable to OPC why are they not widely used. It is possible to use recycled source materials like fly ash and slag but metakaolin has produced better results. However, the metakaolin requires mining of the kaolinite and heat it to make metakaolin. This adds additional steps that are not found with the recycled materials. With different sources of soluble silicate need for the geopolymer production, they also show varied properties. This presents the need to develop a specific process for each source of silicate, which adds time and cost to it cement production. Also contaminants in the fly ash or slag can affect the polymerization reaction and the properties of the final cement product. The cement and building industries currently regulate the amount of non-OPC binder that can be used in the production cement so these regulations will need to be adjusted before any alternative cement product can break in tot the industry. Finally, geopolymers are a relatively new technology and it will take time and to build a reputation in the industry.