High Bond Steel Fibers for Ultra High-Performance Concrete (UHPC)

Monday, January 23, 2023 - 18:30

This project developed a novel type of steel fiber to reinforce ultrahigh performance concrete (UHPC) and demonstrated its use in a recently built bridge. The new fiber has micrometer-scale striations on its surface to ensure highly effective anchorage into the UHPC matrix. The initial research effort focused on identifying the optimal striation configuration and developing a viable technique to manufacture the fibers in commercial volume. An experimental testing program was then conducted to assess the effectiveness of the new surface modification technology. The experiments showed that the surface-modified fibers had a 130% increase in pullout resistance compared to non-modified fibers (i.e. more than double the capacity of the non-modified fibers). When used to reinforce UHPC at the traditional dosage of 2% by volume, the new fibers resulted in a 62% increase in strain at peak stress (the so-called localization strain) compared to specimens with non-modified fibers, i.e. it increased UHPC’s ductility by close to two-thirds. When used at a reduced dosage of 1% by volume, i.e. half the regular dosage, the new fibers resulted in a performance that was on par with non-modified fibers at full 2% dosage. The TRB IDEA report is available online at https://onlinepubs.trb.org/onlinepubs/IDEA/FinalReports/Highway/NCHRP235.pdf


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