Thermo-mechanical treatment of sugarcane bagasse ash with very high LOI: A pozzolanic paradigm

Abstract

The sugarcane bagasse ash (SCBA) with a very high loss on ignition (LOI) (>20%), deficient in silica, has remained unattended and needs sincere attention instead of getting dumped in landfills. With this motivation, the attempts were accomplished to transmute the sugarcane bagasse ash with very high LOI (3 samples with diverse LOI up to 50%) as a pozzolanic material through the thermo-mechanical treatment. The optimum level of re-calcination and particle size was ascertained based on characteristics and pozzolanic reactivity assessed through four different methods. The results of this study ensured that the re-calcination temperature of 600–700 °C preserves the parental amorphous state of SCBA with enhancement in silica. Based on the LOI of as-such received/untreated SCBA, the residence time of re-calcination needs to be decided to fulfill the chemical requirement of ASTM C618. Furthermore, the grinding of re-calcined SCBA until the particle size D50 finer than 35 µm, and particles below 45 µm higher than 60% are the favorable grinding levels for achieving strength activity index (SAI) higher than 75%, provided amorphous silica is higher than 25% and LOI less than 20%. The association of modified Chapelle and Frattini test methods with SAI evident to be an affirmative way to predict the ingenuous pozzolanic reactivity of SCBA.