Mechanical and microstructural properties analysis of one-part geopolymer based on burnt coal cinder replaced by metakaolin

摘要

The development of traditional geopolymer for cast-in-situ applications has been a relatively challenging issue due to the difficulties in handling, transporting, and storing of highly corrosive and viscous alkali solutions. This study developed a green, economical, and user-friendly one-part geopolymer, which is formed by mixing burnt coal cinder (BCC), metakaolin (MK), and solid alkali activators such as sodium hydroxide (NaOH) and sodium silicate (Na2SiO3) and cured un-der elevated temperatures.The effects of parameters such as compressive strength, curing time and temperature, thermal stability, and chemical resistance were investigated. To evaluate the microstructural properties of one-part geopolymers, Brunauer-Emmett-Teller, X-ray diffraction, Fourier transform infrared spectroscopy, scanning electron microscopy, an energy-dispersive spectrometer, and thermo-gravimetric analysis were employed.The results showed that the optimum preparation conditions were 50:50:15:11.64 (g:g:g:g) for BCC:MK:NaOH: Na2SiO3, with a liquid-solid ratio of 0.30, cured at 80 & DEG;C for 24 h and 28 days at room temperature. Significant dissolution and shift of one-part geopolymeric precursors onto the production of new crystalline phases were observed, resulting in more N-A-S-H gel binding substances and the development of properties.Furthermore, the pore size distribution was improved by over 60% compared to their counterparts, and more homogeneity, compactness, and meaningful dense crystal compounds were observed. Despite having the highest compressive strength of 56.61 MPa after 28 days, it substan-tially declined after exposure to several chemical solutions and thermal stability tests. Therefore, a one-part geopolymer can effectively contribute to ensuring the sustainability of solid waste in the construction industry.

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