Toughness Characteristics of Microfiber-Based Geopolymer Concrete Voided Slabs under Soft Impact

Abstract

Abstract The present study aimed to experimentally and numerically analyze voided geopolymer concrete slabs applied with soft impact through a drop-hammer impact setup. Six slabs (600 mm ×600 mm × 115 mm) were cast using geopolymer concrete. Two were cast as solid slabs and the remaining four slabs were cast as voided slabs by placing a 70 mm diameter spherical void formers in two different patterns. Two patterns of void formers are followed as 70 mm void former at 240 mm spacing and 70 mm void former at 120 mm spacing. Micro steel fiber at a dosage of 1 % by volume fraction was added in companion specimens in each case. The placing of void former reduced the self-weight of the slabs by 6 % and 12.6 %, respectively, compared to solid slabs. The soft impact was achieved by releasing a 4.5 kg steel ball from a fall height of 0.457 m in a fabricated soft impact test frame. A similar soft impact test was accomplished numerically using the analysis system (ANSYS) workbench. Parametric analysis shows that when compared to fiber-reinforced solid slabs, the impact resistance of fiber-reinforced voided slabs with 70 mm void former at 240 mm was enhanced. The enhancement percentage for energy absorption, ductility index, and ultimate crack resistance were 34.05 %, 55.26 %, and 9.68 %, respectively. The fiber-reinforced voided slabs were also found to be economical and sustainable with reduced CO2 emission and embodied energy.