Control of Interface Properties between Fiber/Cement Using Plasma Treatment

Inventors: Victor C. Li and Hwai-Chung Wu
US Patent No. 5,788,760
Issued on August 4, 1998

Performance Targets:

  • To control bond strength and Interface Toughness between synthetic fibers and cement-based matrix for strain hardening behavior of high-performance cement-based composites


  • Structures requiring ductile construction material for safety and durability

Suggested Key Words: Fiber surface preparation, strain hardening composites, interface toughness, fiber-cement interface bond

Non-Proprietary Description: The objective of this invention is to control interface properties, particularly bond strength (τ) and interface toughness (Ti), between synthetic fibers and cement-based matrix. It is found that, with an optimum plasma treatment of fibers, as demonstrated using polyethylene fibers, τ can be increased by a factor of 6 and Ti can be increased by as much as 7 times, compared to the virgin non-plasma treated fibers. For fiber reinforced cement-based composites, their practical applications are usually hindered by (1) low τleading to insignificant changes in composite properties, when low fiber dosage (usually < 1 volume percent) is used, and (2) high cost and processing difficulties, when high fiber dosage (usually > 10 volume percent) is used. Much improved interface properties are essential to creating high-performance fiber reinforced cement-based composites which possess high strength and high ductility, requiring fiber volume fraction less than 2% for low cost and easy processing. In this new invention, a novel plasma treatment is developed as to significantly enhance bond strength (related to composite strength), interface toughness (related to composite ductility and composite toughness), or both of synthetic fibers. Thus, this invention can be used to tailor desirable interface properties of any given fiber systems to provide cost-effective high-performance fiber reinforced cement-based composites. For more, read invention disclosure.