Abstract
Panel structures which are mainly used as insulation materials should possess high fire resistance characteristic. In addition, their mechanical requisites for walls and doors such as compressive strength must not be unduly compromised. Rice husk ash (RHA) was used as an aluminosilicate source and two factors namely RHA/AA ratio and NaOH concentration were analyzed using statistical tool to study the effect of both factors on the compressive strength. Surface morphology and fire resistant behavior of four selected samples based on their compressive strength (brittle, semi-brittle, ductile, and semi-ductile samples) were studied to determine the correlation between compressive strength and fire resistant performance of those selected samples. Results showed that RHA-based geopolymer sample recorded high compressive strength above 28 MPa when its RHA/AA ratio and NaOH concentration were high ranging from 0.7 to 0.8 and 12M to 14M, respectively. Brittle geopolymer sample (GS) with low Si/Al ratio shows high compressive strength together with high degree of geopolymerization. Ductile GS in comparison, shows low compressive strength irrespective of its degree of geopolymerization. Semi-ductile GS showed the best fire resistant properties with a maximum non-exposed surface temperature of only 50°C after 50 minutes (after it was exposed to a direct fire with temperature of 900°C) followed by semi-brittle and brittle GS.
Highlights
Rice husks (RHs) is a byproduct of paddy rice processing
Compared to fly ash or other aluminosilicate sources, Rice husk ash (RHA) contained the highest amount of silica which is approximately 85 to 95% and relatively low alumina content which is approximately 0.5 to 2.0%
Higher loading of RHA will result in higher silica content which leads to high Si/Al ratio
Summary
Rice husks (RHs) is a byproduct of paddy rice processing. It is a good source of renewable energy and weight approximately 20% of the harvested paddy. RHs is one of the largest available biomass resources and the low cost of RH [3, 4] may potentially reduce the costs of geopolymer through reducing cost of production compared by using other resin systems available in the market such as polyimides, cyanide esters, silicone, epoxy, polyurethane and acrylic resins. Geopolymer is known for its good mechanical properties and high early-aged strength. The potential advantages of RHA-based geopolymer material, in enhancing its mechanical and thermal properties, are mainly associated with RHA which having high silica content. Compared to fly ash or other aluminosilicate sources, RHA contained the highest amount of silica which is approximately 85 to 95% and relatively low alumina content which is approximately 0.5 to 2.0%. High Si/Al ratio proved to provide higher compressive strength, further increase in Si/Al ratio has a tendency to reduce the compressive strength as studied by Songpirijakij et al [7]
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