研究結果認為，提高石英粉末比例，除了工作性佳之外，拉力性能之表現亦十分優異，僅對壓力強度造成些微損失，發展出在不大幅影響力學性能之前提下，能提供較好工作性之超高性能纖維混凝土。 ;Ultra high performance fiber reinforced concrete (UHPFRC) is a new cement-based material. It is more durable and has a higher strength than traditional concrete. The workability of UHPFRC will influence by the particle size and the type of steel fiber, cause the mechanical performance unstable.
This study investigates the effect of varying percentages of silica sands and quartz powders on the workability and mechanical properties of the UHPFRC. The results show that increasing the amount of usage of silica sands and quartz powders is able to improve the workability of UHPFRC. But it make cause the loss of the fiber distribution ability. Adding a small amount of steel fiber can improve the workability of UHPFRC, but when the amount of fiber increase of 2%, will result in the loss of workability.
In this research, the compressive stress of UHPFRC is up to 120 MPa. The first-cracking stress and the ultimate tensile stress with 2% fiber is about 5 MPa~8 MPa and 6 MPa~10 MPa. The strain at ultimate tensile stress is up to 0.88%. The compressive stress of UHPFRC will decreased with the proportion of silica sands and quartz powders increase. Adding steel fiber also cause the compressive stress loss, and the UHPFRC with 1% fibers will loss more strength than which that with 2% fibers. At higher fiber content and increased content of silica powder, it can enhance first-cracking stress and ultimate tensile stress significantly with strain hardening behavior, it shows that quartz powders can improve the effectiveness of steel fibers. On the other hand, the effect of silica sand content on tensile stress is limited. With the increase of the amount of silica sand, the probability of strain hardening is reduced, show that silica sands will reduce the effectiveness of fibers.
The study concluded that increase the proportion of quartz powders not only improve the workability, but also enhance the toughness of UHPFRC. Developed the UHPFRC that with great workability and mechanical performance successfully.
