碱激发赤泥-矿渣人造骨料及其砂浆性能研究

In this study, alkali activated red mud-slag artificial aggregates were prepared by cold-bonded pelletization technology using red mud and granulated ground blast furnace slag (GGBS) as precursors and sodium silicate as the alkali activator. The experimental results show that bulk densities of the artificial aggregates are less than 1200kg/m³, the average single-particle crushing strength is up to 10. 61 MPa and the cylinder compressive strength is up to 21. 17 MPa, which meets the specification requirements for the lightweight aggregates. The hydration products of artificial aggregates are mainly the calcium-sodium-silicate-hydrate (C-(N)-A-S-H) gels, calcium-silicate-hydrate (C-S-H) gels and a small amount of ettringites (AFts). After 28 days immersion in saturated Ca(OH)₂ solution, no obvious chemical change was detected in the artificial aggregates, indicating that their chemical stability was good in the simulated concrete pore solution. Furthermore, the 28-day compressive strength of cement mortars with the artificial aggregates can reach 54. 2 MPa. The average 28-day compressive strength of mortar with 50% partially replaced artificial aggregates could increase by 24. 6%. In total, red mud can be manufactured as alkali-activated artificial aggregates to address both the shortage of natural aggregates and the recycling of red mud.