Taiyuan, Shanxi Hollow Core Slab (Thin-Walled Box Structure)

Dingwang Building Materials Co., Ltd., Qingxu County, Taiyuan City, Shanxi Province Website: http://www.qingxudingwang.com Contact: Mr. Hu Phone: 18703401090 Detailed Description of Hollow Core Slabs: **Economic Advantages of Hollow Core Slabs in Underground Engineering** 1. **Reduction in Steel and Concrete Usage**: Hollow core slabs significantly reduce the amount of steel and concrete compared to beam-slab structures. For example, in an underground garage with an 8.4m × 8.4m column span, 1.5m of overburden, and a fire truck load of 20 kN, steel usage is reduced by 22 kg/m², and concrete thickness is reduced by 40 mm. The larger the span and load, the greater the economic benefits. However, hollow core slabs incur an additional cost for the hollow components, which is not present in beam-slab structures. The actual savings depend on current market prices. 2. **Reduction in Excavation and Earthwork Transport**: Based on experience, using hollow core slabs in underground construction can reduce floor height by 300–500 mm for non-civil defense areas and 400–600 mm for civil defense structures. For a typical two-level underground building, the total height reduction can reach 800–1,200 mm. With a 1-meter reduction in floor height, earthwork excavation decreases by at least 1 m³ per square meter, saving approximately ¥35/m² in urban areas (based on an excavation cost of ¥35/m³). 3. **Reduction in Retaining Wall Piling Work**: Hollow core slabs reduce excavation depth, lowering earth pressure and resulting in a 13% reduction in pile length and embedment depth. Pile diameter, reinforcement, number and length of anchor rods, and the size of internal bracing components are also reduced. 4. **Foundation Slab Benefits**: A 1-meter reduction in excavation depth lowers the groundwater level by 1 meter, reducing water pressure by P = 1 × 10 = 10 kN/m². This decreases the load on the foundation slab and ground beams by 10 kN/m², allowing for reduced reinforcement, cross-sectional dimensions, and waterproofing requirements. In areas with high groundwater levels, the number and length of uplift piles can also be reduced. 5. **External Wall Benefits**: - Height: Reduced floor height lowers external wall height. - Earth Pressure: Lower excavation depth reduces earth pressure on walls. - Water Pressure: Reduced groundwater level decreases water pressure on walls. - Reinforcement: Lower pressures allow for reduced wall reinforcement. - Waterproofing: Shorter walls reduce the amount of waterproofing material needed. - Impermeability Grade: With unchanged wall thickness, the impermeability grade can be lowered. 6. **Staircase Savings**: Reduced floor height decreases the number of stair flights, saving steel and concrete. 7. **Underground Garage Ramp**: Ramps can be shortened while maintaining the same slope. 8. **Reduced Dewatering Costs**: Lower excavation depth, especially for multi-level basements, significantly reduces dewatering expenses. 9. **Reduced Wall Plastering Work**: The flat underside of hollow core slabs eliminates the need for beam-side plastering, reducing labor and material costs. 10. **Vertical Component Savings**: Columns and walls can be shorter while maintaining the same clear height, resulting in noticeable savings. **Functional and Operational Advantages** 1. **Formwork and Plastering Savings**: Only flat formwork is needed, reducing formwork loss and increasing reuse rates. Beam-side plastering is eliminated. 2. **Faster Construction**: Construction time is shortened by approximately 30%, reducing equipment rental and labor costs. 3. **Fewer Smoke Detectors and Sprinklers**: The flat slab surface allows for a reduction of 5/6 in smoke detectors and 1/3 in sprinklers. 4. **Savings in Vertical MEP Components**: Reduced floor height shortens vertical pipes, ducts, and elevator shafts. For a three-level basement, savings can exceed 1.2–1.8 meters. 5. **Shorter Ramps and Increased Parking Space**: Lower floor height allows for shorter ramps, increasing usable parking area. 6. **Easy Drilling and Mounting**: Holes can be drilled conveniently, and expansion bolts can be installed without precise marking. 7. **Simplified Pipeline Installation**: Ducts and pipes can be installed without detours or diameter changes due to the absence of beams, reducing installation time and cost. 8. **Noise Reduction**: The hollow structure dampens impact noise from vehicles. 9. **Crack Resistance**: The dense network of hidden ribs in hollow core slabs minimizes cracking and enhances structural integrity. 10. **Thermal Insulation**: The closed cavities reduce heat transfer, improving energy efficiency and lowering air conditioning costs. **Certifications and Applications** - National 863 Program Research Achievement - Key Science and Technology Promotion Project by the Ministry of Construction - Suitable for large loads and spans with remarkable economy - Environmentally friendly, energy-efficient, and noise-reducing - Widely adopted in practice