Characterization and reactivity of Nepali clays as supplementary cementitious material

In the global cement industry, use of supplementary cementitious materials (SCMs) to partially replace cement clinker is one of the most successful strategies to reduce CO2 emission. Calcined clay, especially in combination with limestone, has great potential particularly for countries like Nepal, where clay resources are abundant. This study explores the geographical distribution of Nepali clays to characterize their mineral and chemical properties and to investigate their reactivities. A field investigation program was performed to collect clay samples from 25 different locations in Nepal. The clay samples were characterized for their mineral and chemical properties using various methods (e.g. X-ray diffraction, X-ray fluorescence, thermogravimetric analysis). Clay samples were calcined and the reactivity of the calcined clay was investigated by measuring the reaction heat exotherms based on isothermal calorimetry. Finally, for the clay with low kaolinite content, a particle classification technique was applied to increase the reactivity of clay. This research shows that Nepali clays can be used as SCM in concrete and has prospects in large-scale applications in Nepal.