Study on Durability of Steel Fiber Reinforced Mortar
Steel fiber reinforced mortar (SFRM), a composite material by compounding the short steel fibers in mortar uniformly, is considered to improve the resistance against the defect of cracks and toughness in plain mortar. SFRM is now getting more popularity in the application field of construction. The evaluation of durability and service life is important in wide ranges of application. However, only limited information is known concerning the durability of SFRM.
In this study, three sites were chosen to investigate the durability of SFRM. The first site is a tunnel in Garou mine (Hokkaido) where SFRM lining was sprayed 18 years ago. The steel fibers were found to be almost sound except the rusted fibers on/near the wall surface. The tensile and compressive strengths were found to be close to the initial values obtained 18 years ago.
The second site is a slope in Shizuoka Prefecture where plain mortar and SFRM were sprayed in 1994. Investigation of the slope in 1997 showed that mean crack-width on SFRM was considerably smaller than that on plain mortar. The number of cracks on SFRM was only 1/3 of that on the plain mortar.
The third site is seashore in Chiba Prefecture and exposure tests were started in 1996. The compressive strength of SFRM did not change so much for five years. Thereafter, the strength decreased considerably.
KEY WORDS: SFRM, Durability, Steel Fiber, Sprayed SFRM, Neutralization