An Investigation on Pozzolanicity of Mechanically Activated Pond Ash

Abstract

Pond ash (PA) is one of the major industrial solid wastes from thermal power plants. In the present study, PA of different storage durations, i.e. freshly ponded, two year ponded and Six-year ponded ash were collected from Bellary Thermal Plant (BTP). All three kinds of PA were mechanically activated by grinding in Industrial Hammer Mill. Unprocessed Pond Ash (UPA) and Ground Pond Ash (GPA) were characterised for Particle Size Distribution (PSD) by Laser-diffraction analyser. Mineralogical and Morphological characteristics were analysed through X-ray Diffraction and Electron Microscopic studies. Chemical composition of PA was analysed. The pozzolanicity of PA and other Supplementary Cementitious Materials (SCM) was determined and compared by conducting Lime reactivity test. XRD patterns and Chemical analysis clearly indicate the presence of relatively more amorphous phases in a fresh batch of PA compared to the one which is ponded for a longer duration. Lime reactivity strength (LRS) of UPA was far behind the LRS of commonly used SCM's. Mechanical activation of PA improved the LRS from 0.57 MPa to 2.41 MPa. The results suggest the possibility of enhancing the reactivity of PA with early use and more efficient grinding process, thus add value to PA for its use in concrete.