The effect of fiber properties on high performance alkali-activated slag/silica fume mortars

The effects of length and volume fraction of steel fibers on the mechanical properties and drying shrinkage behavior of steel fiber reinforced alkali-activated slag/silica fume (AASS) mortars were investigated within the scope of this research. Steel fibers with two different lengths of 6 mm and 13 mm, and four different volume fractions of 0.5%, 1.0%, 1.5% and 2.0% were used in the AASS mixtures. Also, a Portland cement (PC) based 1.5% steel fiber (13 mm length) reinforced mortar was prepared for comparison. Test results showed that mechanical performance of AASS mortars were significantly better than PC based control mortar. This superior performance of AASS mortar may be attributed to the higher bond properties between the fibers and AASS matrix compared to PC matrix. The mechanical performance of AASS improved dramatically parallel to the increment of fiber length from 6 mm to 13 mm. Also, the drying shrinkage of AASS mortars decreased with the increasing fiber dosage.