Influence of Curing Temperature on the Mechanical Properties of Alkali-Activated Bottom Ash Geopolymer Mortar

Abstract:

The fabrication of Portland cement causes numerous problems accompanying the large exhaustion of gas. Even if fly ash, an industrial by-product produced in thermoelectric power plants, is recycled in concrete by partial replacing of cement, more than 50% remains still discharged in marine and ashore landfills and, continue to provoke environmental problems. Recently, active research has been dedicated to alkali-activated concrete that does not use cement as binder. This alkali-activated concrete as a cement zero concrete activated by alkali solution using bottom ash rich in Si and Al instead of cement is effective in reducing gas exhaustion. This study is a basic research for the fabrication of concrete without cement and using 100% of bottom ash among the industrial by-products. Therefore, the purposes are to develop cement zero concrete by evaluating the mechanical properties by age according to the change of the molar concentration and ratio (SH/SS) of the alkali-activator and the curing temperature, and to investigate the reaction mechanism. From the test results, the compressive strength increased with larger molar concentration and the optimal curing temperature was 60°C. In addition, the measurement of the leaching according to the molar concentration of fly ash having similar chemical composition showed that the leaching of Si⁴⁺ and Al³⁺ increased. Compared to 6M, the leached quantities of Si⁴⁺ and Al³⁺ were twice larger for 9M and 12M. The formation of gel at the surface of fly ash indicated that fly ash was more activated in higher alkaline environment.

• Periodical: Key Engineering Materials (Volumes 488-489)
• Pages: 198-201
• DOI: https://doi.org/10.4028/www.scientific.net/KEM.488-489.198
• Online since: September 2011
• Authors: Gum Sung Ryu, Si Hwan Kim, Kyung Taek Koh, Su Tae Kang, Jang Hwa Lee
• Keywords: Alkali-Activated, Bottom Ash, Compressive Strength, Curing Temperature, Geopolymer

References

[1] Ryu G.S., Koh K.T., Kang S.T., Ahn K.H., Kim S.W., Lee J.H., (2008), An Experimental Study on the Development of Strength of Mortar Using 100% of Fly Ash as Binder, Proceedings of Spring Conference of the Korea Concrete Institute, (2008).

[2] Prinya Chindaprasirt et al. (2009), Comparative study on the characteristics of fly ash and bottom ash geopolymers, Waste Management.

DOI: 10.1016/j.wasman.2008.06.023

[3] Apha Sathonsaowaphak et al. (2009), Workability and strength of lignite bottom ash geopolymer mortar, Journal of Hazardous Materials.

DOI: 10.1016/j.jhazmat.2009.01.120

[4] R. Slavik et al. (2008), Preparation of geopolymer from fluidized bed combustion bottom ash, J. Materials Process Technology.