Influence of silica fume on pore structure, mechanical properties and carbon emission of reactive powder concrete prepared by ice crystal homogenization technology

Under ultra-low water-to-binder ratio conditions, the liquid-bridge effect between powders seriously restricts the development of reactive powder concrete (RPC). Ice crystal homogenization technology fundamentally solves the liquid-bridge problem between powders. However, high carbon emissions still constrain the application of RPC. This paper introduces an innovative RPC material incorporating silica fume (SF) as a supplementary cementitious material to solve environmental concerns and alleviate powder aggregation challenges based on the ice crystal homogenization technology. Experimental results show that there was a significant improvement in compressive and flexural strengths observed, particularly in RPC material containing 15 % SF, which exhibited the most notable enhancements: a 19.7 % increase in compressive strength to 296.3 MPa and a 23.6 % increase in flexural strength to 43.8 MPa. Moreover, the optimized microstructure was reflected in a substantial reduction in water absorption rate and cumulative pore volume by 44.7 % and 54.4 %, respectively. Besides, RPC incorporating 15 % SF achieved the lowest carbon emissions efficiency, with carbon emissions efficiency could be reduced by 79∼93 % compared with conventional UHPC. In conclusion, the use of SF and ice crystal homogenization technology in RPC provides the great potential for developing sustainable construction materials and promoting carbon reduction strategies.