Prefabricated Floor Slabs for Houses in Putian
The prefabricated floor slabs used in houses in Putian are common concrete prefabricated components in early 20th-century architecture, mainly used for floor or insulation layer structures, and have gradually been replaced by cast-in-place structures.
Types and Structural Characteristics of Prefabricated Slabs
Prefabricated slabs are divided into two types: solid and hollow. Hollow prefabricated slabs reduce self-weight and save material costs by designing cavities in non-load-bearing areas, but their overall integrity is poor, and they are no longer recommended for use in modern buildings. Solid prefabricated slabs have a more stable structure but are heavier, resulting in higher transportation and installation costs. Currently, newly built buildings in Putian and across the country mostly adopt cast-in-place concrete structures to enhance the overall seismic performance and durability of the buildings.
Specifications and Load-Bearing Capacity
The common specifications of residential prefabricated slabs in the Putian area are as follows:
- Span: The longest standard span is 4.2 meters, and custom processing is required for spans exceeding this length.
- Width: Mainly 500mm and 600mm.
- Thickness: Commonly 120mm and 150mm.
- Load-bearing grade: Divided into Grade I slabs (live load of 1kN/m²) and Grade II slabs (live load of 2kN/m²). Due to special geological conditions, the minimum requirement in the southwest region is Grade IV slabs (live load of 4kN/m²).
Application and Issues in Old Residential Areas
In old residential areas in Putian with a building age of over 20 years, prefabricated slabs were widely used for floor structures or roof insulation layers. The core issue is concentrated on the risk of leakage:
- Aging of the waterproof layer: The joints of prefabricated slabs are prone to rainwater infiltration due to the failure of waterproof materials.
- Failure of pipe sealing: The poor sealing around pipes passing through the floor slabs (such as drainage pipes) exacerbates leakage.
- Differential structural settlement: After long-term use, cracks may occur at the connections between the prefabricated slabs and the walls due to settlement.
Maintenance and Improvement Suggestions
For the leakage issues of prefabricated slab structures, professional solutions need to be combined for treatment:
- Surface repair: Fill cracks with epoxy resin or polymer cement mortar.
- Reapplication of the waterproof layer: Lay waterproof membranes or apply waterproof coatings on the floor surface, focusing on the treatment of joints and around pipes.
- Structural reinforcement: For severely settled or cracked prefabricated slabs, reinforcement with carbon fiber sheets or partial replacement with cast-in-place slabs is required.
In modern architecture, prefabricated slabs have gradually been replaced by cast-in-place concrete. However, the maintenance of old residential areas still needs to focus on their structural safety and waterproof performance. Regular inspections and targeted measures can extend their service life.
