Prefabricated Hollow Slab for Housing

The prefabricated hollow slab for housing is a concrete slab with a hollow cross-section, also known as a hollow slab. The following provides a detailed introduction from five aspects: characteristics, applications, production, reinforcement, and current status:

Characteristics: The prefabricated hollow slab for housing offers multiple advantages. Compared to solid slabs of the same span, it is lighter in weight and has a lower building height, greatly facilitating transportation and installation. Prefabricated prestressed hollow slabs perform even better, featuring high load-bearing capacity, large spans, light weight, and good seismic performance. The production of hollow prefabricated slabs is based on mechanical principles; the hollow parts of the slab, which do not bear force, are left empty to reduce weight and save costs.

Applications: The prefabricated hollow slab for housing is widely used. In small-span bridges, it is a common structural form. In the construction field, prefabricated concrete hollow floor slabs are extensively applied in various types of buildings, including residential, commercial, educational, medical, and industrial structures. The development history of prefabricated hollow slabs in China is rich. Non-prestressed hollow slabs began to be used in the 1950s, and in the early 21st century, the SP slab (prestressed hollow slab) from the United States was introduced. In March 2025, the national standard atlas for "Prestressed Concrete Hollow Slabs (EHC Slabs)" was released, in which EHC slabs adopt extrusion molding technology and can achieve a maximum span of 20 meters. Most residential buildings constructed in China before 1985 adopted prefabricated hollow slab structures.

Production: The production of the prefabricated hollow slab for housing follows a certain process. First, a hollow mold is made using wooden boards. After reasonably arranging steel bars in the hollow part of the mold, the hollow part is filled with cement. Once the cement dries, the wooden boards are knocked off, leaving the prefabricated slab.

Reinforcement: For the prefabricated hollow slabs in old houses, which are supported on walls at both ends and have steel bars only at the bottom with no steel bars in the longitudinal direction at the top, when the upper load increases, carbon fiber cloth can be pasted on the bottom of the slab for reinforcement. If the load increases significantly, there are also corresponding renovation and transformation methods.

Current Status: Nowadays, the use of prefabricated hollow slabs is no longer encouraged, and cast-in-place structures are more commonly used in building construction because cast-in-place structures result in houses with better overall integrity and are sturdier. Existing buildings using prefabricated hollow slabs have many problems, such as weak seismic resistance, poor sound and heat insulation, and a service life of about 30-50 years. Since 2022, China has implemented a policy of renovating old buildings, focusing on repairing and renovating prefabricated slab buildings and only demolishing those that meet the criteria for dangerous buildings.