Cracks in Prefabricated Laminated Slab Houses

Cracks in prefabricated laminated slab houses are mainly caused by structural deformation, differences in material properties, material issues, construction process problems, and environmental factors. They can be treated by filling the gaps and reinforcing with fabric or using a special anti-crack and waterproof adhesive process.

Causes of Cracks

1. Structural Deformation
   Foundation settlement, temperature changes, and material shrinkage are the main causes. For example, in high-temperature and high-humidity environments, stress concentration at the joints of laminated slabs can easily lead to cracking. When the stress exceeds the tensile limit of the plaster layer and decorative coating, cracks become visible.

2. Differences in Material Properties
   The elastic modulus and coefficient of linear expansion differ among prefabricated laminated slabs, plaster layers, and decorative coatings. Under environmental changes, relative deformation accumulates stress. For instance, in summer high temperatures, the expansion of laminated slabs is 0.5–1.0 mm/m more than that of decorative coatings, making joints prone to cracking.

3. Material Issues

   • Substandard Concrete Quality: Insufficient strength or improper mix proportions can lead to cracking of the base slab.
   • Corroded or Improperly Arranged Reinforcement: Corrosion reduces the bond between reinforcement and concrete, causing cracking.

4. Construction Process Problems

   • Improper Joint Treatment: Insufficient roughening, cleaning, or unreliable reinforcement connections weaken the integrity of the joints.
   • Improper Pouring and Curing: Inadequate vibration or delayed curing can lead to concrete cracking.
   • Insufficient Formwork Support: Unstable support can cause deformation and cracking of the base slab.
   • Improper Decorative Coating Application: Inappropriate temperature and humidity, uneven coating thickness, or poor adhesion can lead to cracking.

5. Environmental Factors

   • Temperature Changes: Excessive temperature differences can cause concrete shrinkage and cracking.
   • Excessive Load: Overloading can directly cause cracking of the base slab.

Crack Treatment Methods

1. Filling and Reinforcement Method
   During renovation, fill the gaps with repair materials and apply an outer layer of dacron fabric, mesh fabric, or carbon fiber fabric. This enhances the material's toughness, disperses stress, and prevents crack propagation.

2. Special Anti-Crack and Waterproof Adhesive Process
   Use PCAA prefabricated partition wall anti-crack and waterproof adhesive, which is based on waterborne acrylic resin and mixed with high-elastic functional materials, inorganic nanomaterials, binders, and anti-aging agents. By spraying or brushing, a flexible waterproof layer is formed, effectively sealing cracks and adapting to minor structural deformations. It is suitable for comprehensive treatment of crack-prone areas such as joints and internal and external corners.