Thermal Resistance of Fly Ash Geopolymers with Alumina as Additive

Abstract:

The present work investigates the effect of alumina addition on the thermal resistance of fly ash geopolymers. Fly ash geopolymers were synthesised by mixing fly ash with activator solution (A mixture of 12M sodium hydroxide and sodium silicate) at fly ash/activator ratio of 2.5 and sodium silicate/sodium hydroxide ratio of 2.5. The alumina (0, 2 and 4 wt %) was added as an additive. The geopolymers were cured at room temperature for 24 hours and 60°C for another 24 hours. After 28 days, the geopolymers was heated to elevated temperature (200 - 1000°C). For unexposed geopolymers, the addition of 2 wt % of alumina increased the compressive strength of fly ash geopolymers while the strength decreased when the content increased to 4 wt.%. The temperature-exposed geopolymers showed enhancement of strength at 200°C regardless of the alumina content. The strength reduced at higher temperature exposure (> 200°C). Despite the strength degradation at elevated temperature, the strength attained was relatively high in the range of 13 - 45 MPa up to 1000°C which adequately for application as structural materials.

• Periodical: Solid State Phenomena (Volume 281)
• Pages: 182-188
• DOI: https://doi.org/10.4028/www.scientific.net/SSP.281.182
• Online since: August 2018
• Authors: Yong Sing Ng, Yun Ming Liew*, Cheng Yong Heah, Mohd Mustafa Al Bakri Abdullah, Hussin Kamarudin
• Keywords: Alumina, Fly Ash, Geopolymers, Thermal Resistance

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