Influence of Curing Temperature on the Mechanical Properties of Alkali-Activated Bottom Ash Geopolymer Mortar: Fid-Bau Portal

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

Ryu, Gum-Sung / Kim, Si-Hwan / Koh, Kyung-Taek / Kang, Su-Tae / Lee, Jang-Hwa

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.