Thermo-Mechanical Beneficiation and Characterisation of Rice Husk Ash

The high carbon footprint of cement urges to explore the pozzolanic potential of ashes obtained after burning of agricultural residues in cogeneration plants. Uncontrolled combustion produces Rice Husk Ash (RHA) containing high unburnt carbon which acts as a stumbling block in its utilisation as a binary binder in cement. In this regard, RHA was obtained by controlled burning of rice husks in an industry set up. Further, thermo-mechanical beneficiation of the obtained RHA was done in order to make it compliant with the Indian and American codal guidelines. Physical, chemical and mineralogical characterisation of both the as-received and the beneficiated RHAs was performed. The results indicate that re-burning of RHA in the temperature range of 600–700 ºC can be performed to reduce Loss-On-Ignition (LOI) below 5% without compromising the amorphous mineralogy of ash. Further, pozzolanic reactivity of the thermo-mechanically beneficiated RHA exhibited higher value compared to the pozzolanic reactivity of as-received RHA.