How to avoid the most common hollowingproblem in the construction of Hangzhou terrazzo prefabricated panel manufacturers?

In the construction of prefabricated terrazzo slabs in Hangzhou, avoiding hollowing problems requires strict control from five core aspects: grassroots treatment, material selection, construction technology, environmental control, and maintenance management. Specific measures are as follows:

1, Grassroots treatment: Ensure stable foundation without hidden dangers
Thoroughly clean and polish
Remove dust, oil stains, floating slurry and other impurities from the surface of the base layer, especially paying attention to building debris falling from the ceiling or walls. If there is floating slurry on the surface of the base layer, it needs to be thoroughly removed by polishing to avoid it becoming an isolation layer and causing a decrease in bonding strength.
For uneven or rough base layers, chiseling or leveling with cement mortar is required to ensure that the flatness error of the base layer does not exceed the specification requirements (such as a 2m ruler inspection deviation of ≤ 3mm), in order to reduce hollowing caused by stress concentration.
Moisturizing and moisture-proof treatment
Before grassroots construction, it is necessary to fully wet it, but avoid water accumulation. Wetting can enhance the bonding strength between the base layer and cement mortar, preventing the mortar from losing water and shrinking due to rapid water absorption by the base layer.
For damp environments or areas such as basements, moisture-proof treatment (such as applying waterproof coating) should be carried out to prevent moisture from penetrating and causing the bonding layer to fail.

2, Material selection: strict quality control and proportioning
Prefabricated board quality
Choose terrazzo prefabricated panels with uniform thickness and minimal deformation, and avoid using products with high water absorption or improper backside treatment. Excessive water absorption can lead to rapid absorption of moisture in mortar, affecting bond strength; Improper backside treatment (such as not roughened) can reduce friction and easily cause hollowing.
Mortar mix ratio
The ratio of cement to sand should be strictly controlled between 1:2 and 1:3 to avoid excessive shrinkage and deformation of the mortar caused by high sand content. At the same time, the mud content of sand should not exceed 3%, otherwise it will reduce the strength of the mortar.
Use high-quality cement (such as Portland cement) and white cement to ensure stable material properties and avoid insufficient bonding due to poor cement quality.

3, Construction technology: standardize operational details
interface processing
Brush a layer of plain cement slurry (with an appropriate amount of building adhesive added) on the surface of the base layer to enhance the bonding strength with the prefabricated board. The brushing time should be strictly controlled to avoid premature drying and hardening, which may cause isolation.
When using dry hanging installation method or dry wet hanging installation method to fix the board, a 2-3mm gap should be reserved to facilitate water evaporation and offset expansion stress, and prevent hollowing caused by stress concentration.
Vibration and compaction
After laying the mortar, gently tap the prefabricated board with a vibrator or rubber mallet to tightly bond it with the cement mortar, eliminate internal air, and avoid hollowing caused by insufficient compaction.
After adjusting the height of the board, it is necessary to check the levelness and verticality again to ensure compliance with the design requirements.
Expansion joint setting
When laying a large area, expansion joints should be set according to the specifications (such as spacing of 6-8m) to prevent hollowing caused by concrete shrinkage. Both sides of the expansion joint should be cut neatly to avoid warping caused by vibration.

4, Environmental Control: Avoiding Adverse Factors
Temperature and Humidity
Avoid working in environments with low temperatures (such as below 5 ℃) or high humidity (such as rainy days). Low temperature can delay the setting of cement mortar, and excessive humidity can lead to high moisture content in mortar, which can easily cause hollowing.
During high-temperature construction in summer, it is necessary to provide shading treatment for prefabricated panels and mortar to prevent rapid evaporation of moisture.
Avoid cross contamination
Ground construction should be carried out after other processes (such as ceiling and wall construction) are completed to prevent floating ash, slurry film, and other pollutants from falling onto the base layer and affecting the bonding effect.
5, Maintenance management: ensuring the quality of solidification
Initial maintenance
Watering and curing should be carried out within 24-48 hours after the laying is completed to keep the cement mortar moist and avoid premature drying that may cause hollowing. During the maintenance period, it is necessary to cover with a damp cloth or plastic film to reduce water evaporation.
Post protection
During the maintenance period, it is prohibited to walk, carry heavy objects or engage in other activities on the ground to prevent damage to the bonding layer caused by external disturbances.
After maintenance is completed, it is necessary to regularly inspect the ground condition, promptly identify and address potential hollowing issues.