Examination of Factors Affecting the Shear Strength of Granulated Blast Furnace Slag

Abstract

Blast furnace slag (BFS) is an alternative material used in various civil engineering functions, such as stabilization of problematic soils, ready mixed concrete production, road and foundation construction and fill material. In this study the geotechnical index properties and shear strength behaviour of Granulated Blast Furnace Slag (GBFS) were determined for fine, medium and coarse grained samples at loose, medium and dense densities. The sieve analysis was performed and GBFS was divided in three sections; coarse (4.75 mm - 2 mm), medium (2 – 0.425 mm) and fine grained (< 0.425 mm) samples. The consolidated drained direct shear tests were conducted with saturated samples at a shear rate of 0.20 mm/min. The test results have shown that GBFS had comparatively higher specific gravity than usual soils (3.0 – 3.4). GBFS was basic (pH >7) and non- plastic characteristic (NP). The maximum shear stress of the samples was obtained at 5% - 10% axial deformation range. The internal friction angle of fine, medium and coarse grained samples were with in the range of 14° - 33°, 27° - 42° and 46° - 50°, respectively. The highest internal friction angle for fine and medium grained samples were obtained for dense samples. Increment of density affects the internal friction angles of medium grained samples positively. However, no significant change in the internal friction angle of the coarse grained samples was observed. The cohesion of GBFS samples ranged between 7 and 39 kPa.