Sustainable Ecological Non-Sintered Ceramsite (SENC) with Alkali Activators: Performance Regulation and Microstructure

The development of novel materials made from waste is one of the main measures to achieve sustainable materials development. In this study, ash of mushroom and corn straw (MCA) and furnace slag (FS) were used as raw materials to prepare alkali-activated biomass ash-slag material (AABS) and sustainable ecological non-sintered ceramsite (SENC). In this paper, the effects of quicklime powder (QL), NaOH, and sodium silicate solution (SS) on AABS were analyzed using single factor and orthogonal tests, and the preferred ratio of the composite alkali activator configuration was established. SENC was prepared based on the composite alkali activator, and the microstructure and phase composition of SENC were explored using XRD and SEM–EDS. The results showed that 3 wt% QL enhanced the early age compressive strength of AABS. The composite alkali activator was best configured when the additions of QL, NaOH, and SS were 3%, 2%, and 15%, respectively. At this configuration, the 28 d compressive strength of AABS was 47.4 MPa, and most of the internal pores were less than 0.4 μm; the 28 d numerical tube pressure of the SENC reached 12.2 MPa with a softening coefficient of 0.96. According to the results of XRD and SEM–EDS, SENC contained various hydration products such as C-A-S-H, calcium hemicarboaluminate, hydrotalcite, portlandite, and vaterite. The largest proportion of hydration products was C-A-S-H, which contributed to the pore refinement and structural densification. SENC has the potential to be used as coarse aggregate in sustainable lightweight concrete.