Abstract
Combustion of biomass is increasingly practiced for power generation. Unlike coal ash, the combustion ashes of biomass do not offer significant value in Portland cement concrete production. An experimental study was conducted in order to assess the value of the combustion ashes of different non-wood biomass types towards production of alkali activated binders for concrete production. The results indicated that concrete materials with a desired balance of fresh mix workability, set time and compressive strength can be produced used alkali activated non-wood biomass ash binders. Correlations were drawn between the concrete engineering properties and different non-wood biomass ash characteristics. It was found that statistically significant relationships exist between the concrete properties and the non-wood biomass ash degree of crystallinity and solubility. These two ash characteristics were also found to be correlated. It was concluded that the suitability of non-wood biomass ash for use in production of alkali activated concrete can be assessed based on its degree of crystallinity.
Highlights
Alkali-activated binders for concrete production and other applications are produced by reactions involving an alkaline solution and an aluminosilicate precursor [1, 2]
Figure 7. presents the linear relationship between the fresh mix workability and the degree of crystallinity of non-wood biomass ash, which was found to be statistically significant at a significance level of 0.017
Multiple variable regression analyses were performed in order to assess the statistical significance of the effects of different non-wood biomass ash characteristics on the strength of non-wood biomass ash-based concrete
Summary
Alkali-activated binders for concrete production and other applications are produced by reactions involving an alkaline solution and an aluminosilicate precursor [1, 2]. The alkaline solution accelerates the dissolution of the solid (aluminosilicate) precursor. These binders provide a high degree of moisture resistance and chemical stability as far as they can produce a highly coordinated (overwhelmingly Q4) ‘geopolymeric’ structure. The primary constituents of non-wood biomass combustion ashes which qualify them as precursors for production of alkali-activated materials are silica, alumina, and alkalis. In the work reported here, the effect of the non-wood biomasses characteristics on the alkali activated concrete fresh mix workability, initial set time and compressive strength were evaluated
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