In the context of Australian commercial construction projects, "hollow core" typically refers to hollow core slabs, which are precast concrete elements used in floor and roof construction. These slabs are characterized by continuous voids or cores running through their length. The primary purpose of these voids is to reduce the weight of the slab without significantly compromising its structural integrity.

Here are some key features and benefits of hollow core slabs:

1. Weight Reduction: The hollow cores reduce the overall weight of the slab, which can lead to savings in the supporting structure and foundations.

2. Material Efficiency: By using less concrete, hollow core slabs are more material-efficient compared to solid slabs.

3. Span Capability: They can span longer distances than traditional concrete slabs, which can reduce the need for intermediate supports and allow for more open floor plans.

4. Speed of Construction: Being precast, hollow core slabs can be manufactured off-site and then quickly installed on-site, speeding up the construction process.

5. Fire Resistance: Concrete provides good fire resistance, and hollow core slabs are often designed to meet specific fire rating requirements.

6. Sound Insulation: The mass of the concrete provides good sound insulation properties, which can be beneficial in commercial buildings.

7. Thermal Mass: Concrete's thermal mass can help in regulating indoor temperatures, contributing to energy efficiency.

In Australian commercial construction, hollow core slabs are commonly used in multi-story buildings, parking structures, and other applications where efficient, rapid construction and long spans are desirable.