Mixed hydrogen and biofuels cement clinker: Characterisation, microstructure, and performance

Over 35 % of the CO2 associated with cement production comes from operational energy. The cement industry needs alternative fuels to meet its net zero emissions target. This study investigated the influence of hydrogen mixed with biofuels, herein designated net zero fuel as an alternative to coal, on the clinker quality and performance of cement produced in an industrial cement plant. Scanning electron microscopy, X-ray diffraction and nuclear magnetic resonance were coupled to study the clinker mineralogy and polymorphs. Hydration and microstructure development in plain and slag blended cements based on the clinker were compared to commercial cement equivalent. The results revealed a lower alite/belite ratio, but a significant proportion of the belite was of the α′H-C2S polymorph. These reacted faster and compensated for the alite/belite ratio. Gel and micro-capillary pores were densified, which reduced total porosity and attained comparable strength to the reference plain and blended cement. This study demonstrates that the investigated net zero fuel-produced clinker meets compositional and strength requirements for plain and blended cement, providing a feasible pathway for the cement industry to lower its operational carbon significantly.