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.
Geopolymer Concrete <ul><li>Hardened cementitious paste made from flyash and alkaline solution. </li></ul><ul><li>Combines waste products into useful product. </li></ul><ul><li>Setting mechanism depends on polymerization. </li></ul><ul><li>Curing temp is between 60-90 degree celcious. </li></ul>
CONSTITUENTS OF GEOPOLYMER CONCRETE <ul><li>Source materials : </li></ul><ul><ul><ul><ul><ul><li>alumina-silicate </li></ul></ul></ul></ul></ul><ul><li>Alkaline liquids </li></ul><ul><ul><ul><ul><ul><li>combination of sodium hydroxide (NaOH) or potassium hydroxide (KOH) and sodium silicate or potassium silicate. </li></ul></ul></ul></ul></ul>
Preparation of geopolymer concrete Geopolymerisation Storage Aggregate Fly ash Alkaline activator NaOH + Na Silicate
The aggregates are prepared in saturated-surface-dry (SSD) condition, and are kept in plastic buckets with lid Dry Materials of Geopolymer Concrete
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
The liquid component of the mixture is then added to the dry materials and the mixing continued usually for another four minutes <ul><li>Addition of Liquid Component </li></ul>
The fresh concrete could be handled up to 120 minutes without any sign of setting and without any degradation in the compressive strength <ul><li>Fresh Geopolymer Concrete Ready for Placing </li></ul>
The workability of the fresh concrete was measured by means of the conventional slump test Slump Measurement of Fresh Geopolymer Concrete
Boundary between Geopolymer binder , aggregate and reinforcement
ADVANTAGES <ul><li>Cutting the world’s carbon. </li></ul><ul><li>The price of fly ash is low. </li></ul><ul><li>Better compressive strength. </li></ul><ul><li>Fire proof. </li></ul><ul><li>Low permeability. </li></ul><ul><li>Eco-friendly. </li></ul><ul><li>Excellent properties within both acid and salt environments. </li></ul>
<ul><li>Different source materials </li></ul><ul><li>Properties of soluble silicate </li></ul><ul><li>Contaminants </li></ul><ul><li>Industry regulations </li></ul><ul><li>New material </li></ul>
<ul><li>The reduced CO 2 emissions of Geopolymer cements make them a good alternative to Ordinary Portland Cement. </li></ul><ul><li>Produces a substance that is comparable to or better than traditional cements with respect to most properties. </li></ul><ul><li>Geopolymer concrete has excellent properties within both acid and salt environments </li></ul><ul><li>Low-calcium fly ash-based geopolymer concrete has excellent compressive strength and is suitable for Structural applications. </li></ul>
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