A technique for preparing one-part geopolymers by activating alkali-fused lithium slag with solid sodium silicate

• Published in: Construction & building materials 2024-07, Vol.435, p.136817, Article 136817
• Main Authors: Luo, Xiaofeng, Huang, Liang, Wei, Linggang, Chen, Mengdong, Zhou, Zhangtao, Zhang, Tao
• Format: Article
• Language: English
• Subjects: Alkali fusion; Compressive strength; Lithium slag; One-part geopolymer; Reactivity
• ISSN: 0950-0618; 1879-0526
• DOI: 10.1016/j.conbuildmat.2024.136817

Lithium slag (LS) exhibits potential as a silica-alumina precursor for geopolymer synthesis, yet its limited reactivity poses challenges for widespread application in one-part geopolymers. This study employs alkali fusion activation to enhance LS reactivity and investigates the underlying mechanisms using XRD, FTIR, and ICP techniques. Results reveal that post-alkali fusion treatment transforms spodumene and quartz within LS into amorphous phases, significantly increasing the amorphous content from 15.9% to 53.1%. However, excessive inclusion of sodium hydroxide (NaOH) during alkali fusion reduces the amorphous phase content. Alkali fusion also enhances LS leaching concentration in an alkaline solution, but an overly abundant incorporation of NaOH adversely affects Si and Al leaching. Within specific parameters, increasing the alkali solution concentration and dissolution temperature enhances Si and Al leaching from LS. Subsequently, alkali-fused LS, along with slag and fly ash, is utilized to fabricate a one-part geopolymer that exhibits outstanding compressive strength. Results indicate that the compressive strength of alkali-fused LS geopolymer consistently surpasses that of the initial LS geopolymer during the curing period, reaching 50.6 MPa after 28 days. Alkali fusion effectively raises the pH of the geopolymer pore solution, promoting the formation of N(C)-A-S-H gel. The overall structure of the geopolymer prepared from alkali-fused LS is dense, with unreacted particles covered by a flocculent gel. However, excessive NaOH incorporation during alkali fusion reduces LS reactivity, diminishing the formation of N(C)-A-S-H gel. Simultaneously, the alkaline environment resulting from excessive NaOH facilitates carbonation reactions in geopolymer samples, thereby reducing compressive strength. •Alkali fusion altered the phase composition and crystalline structure of lithium slag.•Alkali fusion facilitated the leaching of Si4+ and Al3+ from lithium slag.•One-part geopolymer was prepared using alkali-fused lithium slag.