Images of Cracks in Prefabricated Floor Slabs

Currently, it is not possible to directly provide images of cracks in prefabricated floor slabs, but we can offer a scientific explanation of the common forms and causes of such cracks based on professional knowledge:

Common Forms of Cracks in the Prefabricated Slabs Themselves

• Unidirectional cracks parallel to one side wall: These cracks typically appear on the floor slabs of old houses with prefabricated slabs. They are characterized by a single direction of crack propagation and remain parallel to one side wall of the house. The main cause is the asynchronous deformation of two prefabricated slabs during long-term use due to factors such as loads from different directions, temperature changes, or uneven settlement of the foundation, leading to cracks at the connection points. For example, during seasonal transitions when temperature variations are significant, the prefabricated slabs will expand and contract to varying degrees due to thermal expansion and contraction. If the expansion and contraction amounts of the two slabs differ greatly, such cracks are likely to occur.
• Vertical cracks on the side of the slab end: These cracks are often found on the side of the slab end of prefabricated slabs, with the crack direction perpendicular to the ground. This situation is usually caused by warping of the prefabricated slab or uneven support padding. When the prefabricated slab is subjected to improper external forces during production, transportation, or installation, or when the support padding materials are uneven or unstable during installation, it can lead to uneven local stress on the prefabricated slab, resulting in warping and the formation of vertical cracks on the side of the slab end.

Common Forms of Cracks in the Plaster Layer

If the cracks appear in the plaster layer rather than the prefabricated slab itself, they usually manifest as irregular cracks. This is because the bonding force between the plaster layer and the prefabricated slab may be weakened by various factors, such as improper base treatment during plaster layer construction, poor quality of the plastering materials, or changes in environmental humidity. When these factors cause local failure of the bonding between the plaster layer and the prefabricated slab, the plaster layer will develop irregular cracks under its own weight or slight external vibrations. For example, in a humid environment, the plaster layer absorbs water and expands, then contracts after drying. The repeated expansion and contraction process can easily reduce the bonding force between the plaster layer and the prefabricated slab, leading to irregular cracks.