Characterization of cogeneration generated Napier grass ash and its potential use as SCMs

The aim of present study was to investigate the potential utilization of one cogeneration generated biomass ash Napier grass ash (NGA) as SCMs in cement-based materials. The chemical and mineral composition of NGA and its morphology characterization were investigated by means of XRF, XRD and SEM. In addition, the effect of NGA addition on the hydration of blended mixtures was studied by means of isothermal calorimetry. Furthermore, the effect of NGA addition on the properties of blended mortars was characterized by flowability and mechanical strength. The results show that the NGA from the industrial process presents irregular shapes with roughness and porosity surface textures and contains high silica content as well as high LOI. Further thermal treatment at 400 °C was applied aiming to reduce the LOI. The cement replacing by NGA (20% by mass) can partially contribute to the cement hydration. The mechanical strength results indicate that the NGA can meet the requirement to classify the material as a pozzolan no matter whether a further burning process was applied or not. In the present study, the pozzolanic behavior of NGA is slightly higher than that of FA, in terms of compressive strength. It will be of great interest to optimize the combustion technology to produce NGA ashes with lower LOI, aiming to improve its performance in mortar preparation.