Ceramics-Silikáty 69, (1) 19 - 29 (2025)

Manufactured sand (MS) is widely produced and used in concrete. The effects of the fine particle content of the MS on the mechanical properties of UHPC were investigated in this study. Experimental studies on the mechanical properties, including the compressive and flexural strength, splitting tensile strength, and elastic modulus, of UHPC with MS were carried out, and the microscopic mechanism was identified via water absorption, SEM, and XRD. The results indicate that the fine particles (˂0.075 mm) in the MS significantly improve the mechanical properties of UHPC. The MS UHPC with greater than 6% fine particle content had better mechanical properties than those made with natural sand. The mechanical properties of MS UHPC developed rapidly during the early stages, reaching more than 70% of the highest value within 7 days and then stabilising after 28 days. According to the water absorption test, and the SEM and XRD results, the microstructure of the UHPC became denser with the increasing MS content, which can be mainly attributed to the dense filling effect of the MS fine particles in the UHPC.