Investigating the influence of precursor combinations on the development of one-part alkali-activated binders using SiMn

Two-part alkali-activated materials are typically comprised of powders rich in aluminosilicates combined with solutions containing alkali silicates as activators, exhibiting properties akin to cement. However, the use of highly alkaline solutions poses health, safety, and environmental risks during field operations, making the one-part concept a better alternative for in-site applications. This paper aims to investigate the influence of precursor combinations on the development of one-part alkali-activated binders. To achieve this, silico manganese slag (SiMn) was partially replaced by various aluminosilicate precursor powders, including granite powder, crystalline silica flour (SF), amorphous micro silica (MS), and ground granulated blast furnace slag (GBBFS). A potassium silicate powder with a molar ratio of 3.9 was used as the alkaline activator in all mixes. Compressive strength test results indicated that the materials gained strength over time. The highest compressive strength among the binary combinations corresponds to 90 % SiMn and 10 % GGBFS yielding an average compressive strength of 47.8 MPa at 28 days. The presence of a high content of calcium and magnesium aluminosilicates from the slags enhanced the activation reaction, resulting in elevated compressive strength. However, the binary combination with MS provided the lowest strength, reaching about 20 MPa after 28 days. The samples substituting 50 % of SiMn with MS were not practical due to the high specific surface area of MS. Scanning electron microscope (SEM) images also confirmed denser and well-bonded structures for the slag mixes which, are in accordance with the compressive strength results.