In the past, imported ultra-high performance concrete (UHPC) raw materials, if using synthetic fibers, often included imported coarse denier polyvinyl alcohol (PVA) fibers, with a recommended addition of 18 kg per ton of dry powder. It is well known that imported PVA fibers have very high tensile strength (around 1600 MPa) and elastic modulus (around 40 GPa), leading many to the misconception that higher fiber mechanical properties equate to better reinforcement. However, in actual use, this idea proved incorrect, and the concrete still failed to achieve the desired results.
Why is this?
After years of research in fiber-reinforced concrete, several overseas-trained PhDs at Shike have discovered that higher fiber properties do not necessarily mean better reinforcement. Rather, all fiber properties must match the properties of the concrete matrix; a higher degree of matching results in better reinforcement. Fiber properties include many factors, such as addition amount, material, aspect ratio, apparent shape, tensile strength, and elastic modulus. Therefore, mechanical properties are only one part of the many properties of fibers; judging the quality of fibers solely based on mechanical properties is like the blind men and the elephant. Each property of a fiber needs to be matched with its other properties and the properties of the concrete matrix. In other words, excessively high performance in one fiber property is undesirable, as it can negatively impact the performance of other properties.
Through extensive testing, Shike has discovered that even though its high-toughness polypropylene fiber has significantly lower mechanical properties than imported polyvinyl alcohol (PVA) fiber, its reinforcing effect in ultra-high performance concrete (UHPC) is higher, even considerably higher, than that of imported PVA fiber.
Conclusion
In reinforcing UHPC, Shike YBA12 at 15 kg/ton is superior to BMA 12, superior to TMA12, and superior to imported PVA coarse denier fiber at 18 kg/ton. Specifically, Shike YBA 12 shows approximately 50% improvement over imported PVA fiber in two key indicators: post-cracking trough and peak reinforcement.
Website: www.china-pva.net
Whatsapp: 0086-15380400285
E-mail: sales2@china-pva.net
