Precast concrete is manufactured and cast in a factory according to the required shape before being installed on-site for civil engineering construction. This method offers advantages because mixing, casting, finishing, and curing are performed under controlled conditions, ensuring better supervision and producing concrete of higher and more consistent quality compared to cast-in-place concrete. Among the various types of precast systems, the half-slab is widely used in floor construction. A half-slab is a type of concrete floor slab constructed by combining precast concrete with an in-situ topping of fresh concrete to form a full slab. The use of half-slabs in construction presents challenges, particularly in lifting and connecting them to beam structures due to their weight. To reduce this weight, cavities are introduced at the bottom of the slab. In this study, 4 × 4 × 4 cm styrofoam cubes were used to create these cavities. Additionally, 1% steel-wire fibers were incorporated to enhance concrete flexural strength, while fly ash was used as a partial cement substitution to produce self-compacting concrete (SCC). According to the flexural strength test on the half-slab with cavities, an improvement of 26.19% and 35.44% over the normal concrete half-slab was observed, attributable to the presence of fly ash and the combined application of fly ash with steel wire. The observed improvement is further validated by analytical calculations, which demonstrate consistently higher values.
Rochman et al. (Mon,) studied this question.