Title:
Admixture Blends in Steel Fiber-Reinforced Dry-Mix Shotcrete
Author(s):
N. Banthia and V. Bindiganvile
Publication:
Concrete International
Volume:
24
Issue:
8
Appears on pages(s):
59-63
Keywords:
DOI:
Date:
8/1/2002
Abstract:
Shotcreting is fast becoming the preferred method for placing concrete in repair and retrofit projects, in mining and tunneling, for slope stabilization, and for producing large precast products. However, in dry-process shotcreting much material is lost due to rebound—aggregates and cement that bounces off the application surface. The rebound consists mostly of aggregate, which reduces the stiffness of the in-place shotcrete, increases its potential for creep, and makes it highly prone to shrinkage cracking. While silica fume is very successful in reducing fiber rebound and ensuring a high in-place fiber volume fraction, the brittleness introduced into the matrix due to silica fume adversely affects the toughness characteristics. The solution, therefore, is in blending silica fume with another admixture, such as high-reactivity metakaolin, whereby a significant reduction in fiber rebound is achieved without a compromise in the toughness and deformability.