Bearing Weight of Prefabricated House Slabs
The bearing weight of prefabricated house slabs is not a fixed value and is influenced by factors such as type, specifications, span, material properties, support conditions, and load type. The bearing ranges for common types are as follows:
1. Concrete Hollow Slabs Commonly used in rural self-built houses and old residential building floors, calculated based on uniformly distributed loads, with national standards ranging from 200 to 250 kilograms per square meter. For example, a hollow slab that is 3.6 meters long and 0.6 meters wide has an area of 2.16 square meters and a total bearing capacity of approximately 432 kilograms (2.16 × 200), allowing for the uniform placement of 8 bags of 50-kilogram cement; however, concentrated stacking may lead to cracking. The shorter the span, the stronger the bearing capacity. For instance, a hollow slab with a 2.4-meter span can reach 250 kilograms per square meter, while spans over 4.2 meters may drop to 150-180 kilograms per square meter.
2. Solid Prefabricated Slabs Used in areas with heavier loads (such as kitchens and bathrooms), with a bearing capacity of 250 to 300 kilograms per square meter. Solid slabs produced by large factories (with sufficient reinforcement and a concrete grade of C30 or higher) can reach 300 kilograms per square meter, supporting the weight of a 200-kilogram bathtub plus a person. Thickness and reinforcement directly affect the bearing capacity; a 10-centimeter-thick slab is stronger than an 8-centimeter-thick one, and thicker, denser steel bars (such as 8-millimeter steel bars spaced 15 centimeters apart) can enhance the bearing capacity.
3. Prestressed Prefabricated Slabs Commonly used in new buildings, these slabs enhance crack resistance and bearing capacity through high-strength steel wire tensioning. For spans within 3 meters, the bearing capacity is 300 to 400 kilograms per square meter; for spans over 4 meters, it is 250 to 300 kilograms per square meter, which is 20% higher than that of ordinary slabs of the same span.
4. Other Standard References Residential prefabricated slabs are classified into grades: Grade 1 has a bearing capacity of 1 kN/m² (approximately 102 kilograms per square meter), Grade 2 has a bearing capacity of 2 kN/m² (approximately 204 kilograms per square meter), with the highest reaching Grade 4. National standards for ordinary concrete prefabricated slabs stipulate that the live load for residential floors should be at least 200 kilograms per square meter, with a total bearing capacity (including self-weight) of approximately 760 kilograms per square meter; in practice, a 10-centimeter-thick slab can bear 150 to 250 kilograms, while a 12-centimeter-thick slab can reach 250 kilograms.
Key Considerations The type of load significantly impacts the slab's performance: concentrated loads (such as heavy objects stacked at a single point) are more likely to cause cracking than uniformly distributed loads. For example, a slab with a bearing capacity of 200 kilograms per square meter can uniformly support 200 kilograms of sand, but placing a 300-kilogram safe may cause cracking. In practical applications, whether a 4-meter prefabricated slab can bear 2 tons depends on the placement position: concentrated in the middle, it is prone to breaking, while dispersing the load towards both ends and close to load-bearing walls, with multiple support points established, can allow it to bear the weight. To test the bearing capacity, one can refer to architectural drawings or contact a professional agency to use a pressure gauge for testing; overloading by 400 kilograms may cause cracks, while a concentrated load of 20 tons may lead to collapse.
