Hollowcore

Hollowcore refers to a class of precast concrete floor and roof slabs that incorporate a series of hollow longitudinal cores running along the length of the element. The voids reduce weight and material usage while maintaining structural strength, enabling longer spans and faster installation compared with solid slabs. Hollow-core slabs are typically prestressed concrete elements, produced by extrusion or long casting around void-formers to create parallel channels.

Manufacturing and design: The cores are formed during production, and the slab can be prestressed by pretensioning tendons to increase stiffness and span capability. After curing, tendons may be released to impart prestress. The top surface is usually finished with a concrete or cementitious topping to provide the wearing surface and adjust fire and acoustic performance.

Applications: Hollow-core slabs are widely used as floor and roof systems in residential, commercial, and institutional buildings, particularly in multi-story construction. Panels are delivered to site, placed over supporting beams, and connected with joints. Finishes may include a topping layer or, in some designs, dry joints that require less on-site concrete work.

Advantages: They offer reduced dead load compared with solid slabs, which can lower framing costs; potential for longer spans; rapid on-site installation due to factory fabrication; and improved thermal and acoustic performance when paired with appropriate toppings.

Limitations: Field modifications are more difficult; design and construction must address joint behavior, service penetrations, and fire ratings. Heavy lifting equipment is often required, and not all load scenarios or renovations suit hollow-core systems.

See also: precast concrete, prestressed concrete, floor systems, hollow-core slab standards.