Co-synthesis of high-strength sintered ceramsite from biomass bottom ash and retired wind turbine blades

Abstract

Biomass bottom ash (BBA) and retired wind turbine blades (RWTB), as bulk solid waste generated by the renewable energy industry, present substantial potential for the resource-efficient utilization. In this study, high-strength ceramsites were synthesized using BBA and RWTB as raw materials through sintering. The effects of the raw material ratios, sintering temperature, and sintering duration on the physical properties, microstructure, and crystalline phases of the ceramsites were analyzed by FTIR, XRD, SEM-EDS, and thermodynamic methods. The RWTB incorporation contributed to the enhancement of the compressive strength, whereas elevating the sintering temperatures and prolonging the sintering duration exerted a negative impact on the mechanical properties. The optimal conditions were determined to be the BBA to RWTB mass ratio of 70 %:30 %, the sintering temperature of 1160 ℃ and the sintering duration of 15 min. The synthesized ceramsites exhibited apparent density of 1.893 g/cm³, 1h-water absorption of 0.083 %, particle shape coefficient of 1.103, bulk density of 0.872 g/cm³, and compressive strength of 32.31 MPa. The spontaneous thermodynamic reactions facilitated the formation of a uniformly distributed pore structure and an appropriate crystalline phase composition. Subsequently, the ceramsite contained 36.3 % amorphous phase and 63.7 % crystalline phase with albite, anorthite, diopside, mullite, and quartz as the primary crystalline phases to improve the mechanical properties. Additionally, reconstruction of the crystalline phases promoted the stabilization of heavy metals to guarantee that the leaching concentrations meet the limits specified in GB 5085.3–2007. On the whole, a potential pathway for the utilization of BBA and RWTB is provided in this study.