Experimental investigation on fresh and mechanical properties of self-compacting concrete using sisal and abaca fibers

The influence of natural fibers on self-compacting concrete (SCC) with a constant 15% silica fume (SF) was investigated. The natural fibers, namely Abaca fiber (AF) and sisal fiber (SiF), were used in SCC. Initially, it aims to determine the ideal dosage of fibers under mono addition by investigating their fresh properties and mechanical properties. In SCC, the addition of AF 0.25% and 0.5%, and SiF from 0.25% to 1.5% were used with a 0.25% increment. AF at 0.25% ensured a good flow with 6.6% higher compressive strength and 4.16% higher split tensile strength than 0.5% AF. SiF up to 1% obtained good tensile and compressive strength over the optimal AF of 0.25%. Further, combining optimal mono fibers to examine the behavior of hybrid fiber additions in SCC. Hybrid fiber incorporation abruptly reduced the spread flow diameter (SFD), ranging from 330-375 mm, whereas in the mono fiber addition, SFD was 360-600 mm. However, the hybrid fiber combination with AF (0.25%) and SiF (0.5%) performed better than other hybrid mixes, mono fiber additions, and control mixes in terms of compressive strength (22.22%), split tensile strength (26.08%), flexural strength (28%), and impact energy (527.95 %). From microstructure studies through SEM examination, the presence of SF refined the pores caused by the addition of fibers and then enhanced the bond between the fiber and the concrete matrix.