| Title |
Magnesium sulphate resistance of fly ash one-part geopolymers: Influence of solid alkali activators on physical, mechanical and chemical performance |
| ID_Doc |
12164 |
| Authors |
Wan-En, O; Yun-Ming, L; Cheng-Yong, H; Abdullah, MMA; Ngee, HL; Pakawanit, P; Lee, WH; Ken, PW; Hoe-Woon, T; Yu-Xin, Y |
| Title |
Magnesium sulphate resistance of fly ash one-part geopolymers: Influence of solid alkali activators on physical, mechanical and chemical performance |
| Year |
2024 |
| Published |
|
| Abstract |
The commitment to promoting circular economy and durable construction materials has led to the advocacy for one-part geopolymer (OPG), as an eco-friendly substitute for traditional ordinary Portland cement (OPC). Solid alkali activator is the fundamental component of OPG and significantly influences the sulphate resistance. To identify the types of solid alkali activators best suited for the development of sulphate-resistant OPGs, OPGs activated with Na2SiO3 2 SiO 3 (M-OPG), Na2SiO3+Na2CO3 2 SiO 3 +Na 2 CO 3 (MC-OPG), Na2SiO3+NaOH 2 SiO 3 +NaOH (MH-OPG) and Na2SiO3+NaAlO2 2 SiO 3 +NaAlO 2 (MA-OPG) were exposed to 5 % and 10 % of MgSO4 4 solutions for 28 days. The fine pore structures of MH-OPG and MC-OPG mitigated deterioration from the more concentrated MgSO4 4 solution, resulting in higher residual compressive strengths after exposure to the 10 % MgSO4 4 compared to the 5 %. Exposure to the 5 % MgSO4 4 solution resulted in strength deterioration for M-OPG, MH-OPG and MC-OPG due to the discontinuity of the aluminosilicate structure, as evidenced by the diminished Q4(3Al) 4 (3Al) sites. Conversely, the MA-OPG exhibited a 24.1 % increase in compressive strength, accompanied by the emergence of sodium magnesium aluminium silicate hydrate ((N,M)-A-S-H) gel. Hence, Na2SiO3+NaAlO2 2 SiO 3 +NaAlO 2 should be acknowledged as the primary candidate for solid alkali activators in the development of sulphate-resistant OPGs. |
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