Experimental Investigation of the Effect of Nano Silica Fume on Durability of Concrete with Close-Packing Aggregate.

Achieving the close packing and interlocking of coarse aggregates in concrete enhances the elastic modulus, thereby reducing deformation, and can improve the overall stiffness of concrete structures. This study focuses on reinforcing and toughening concrete with close-packing aggregate with silica fume and micro-steel fibers, and investigates its durability properties, including long-term mechanical performance, water absorption, and sulfate erosion resistance under dry-wet cyclic exposure. The experimental results indicate that the 360-day long-term compressive strength of the concrete reaches up to 109.3 MPa, and the 360-day flexural strength reaches 11.62 MPa. The addition of silica fume effectively reduces the water absorption of concrete with close-packing aggregate and improves its sulfate erosion resistance under dry-wet cycles. The lowest 28-day water absorption rate is 2.41%, and after 150 cycles of sulfate erosion, the compressive strength corrosion resistance coefficient of the concrete can be maintained at up to 68.4%, while the sulfate erosion resistance grade reaches up to KS120. The concrete overall exhibits excellent durability properties. Moreover, this is beneficial for enhancing the concrete's performance under dry-wet cycles and its resistance to the effects of sulfate attack.