Practices in Prefabricated Concrete House Construction
Prefabricated concrete house construction itself is not a deceptive practice, but attention should be paid to issues such as module joint aging and limited upgradeability during its promotion and application; in rural house construction, there are practices of cutting corners in concrete construction, such as adding water on-site, substituting concrete grades, and neglecting vibration.
Core Characteristics of Prefabricated Concrete Houses
Prefabricated concrete houses are produced through standardized factory production of components (such as wall panels, floor slabs, and stairs), which are then transported to the site for assembly, offering significant advantages:
- High Construction Efficiency: In Henan, it takes only 4 hours to hoist and assemble a house, significantly shortening the construction period.
- Cost Control: The cost per square meter is approximately 300 yuan, with a total cost of about 60,000 yuan for a 200-square-meter rough-finished house, highlighting its economic efficiency.
- Reliable Structure: The main structure is made of reinforced concrete, with a designed lifespan of 70 years, suitable for residential and office buildings up to 5 stories. However, limitations should be noted:
- Hidden Dangers at Joints: The grouting material at module joints is prone to aging in humid and hot environments, with a project in Zhengzhou experiencing joint water leakage after 5 years.
- Difficult Renovation: If underfloor heating needs to be installed or the layout adjusted, entire walls may need to be demolished, offering less flexibility than cast-in-place structures.
Practices of Cutting Corners in Rural Concrete House Construction
Adding Water On-site Workers add water directly to the hopper to address issues such as dry concrete and pumping difficulties, disrupting the scientific ratio of water, cement, and aggregates. Consequences: Air pockets form inside the concrete, reducing its strength from C30 to C25, leading to cracking, water leakage, and sanding of the floor slab.
Substituting Concrete Grades Construction parties substitute the contracted C30 concrete with C25 or even lower grades, saving tens of yuan per cubic meter in material costs. Consequences: Low-grade concrete has insufficient load-bearing capacity, causing serious issues such as wall cracking, floor slab deformation, and foundation settlement.
Neglecting Vibration To meet deadlines, workers simply insert the vibrator into the concrete, skipping key areas such as beam-column joints and steel reinforcement-dense zones. Consequences: Air bubbles accumulate inside the concrete, with loose aggregates forming honeycombs, pitted surfaces, and even hollow layers, reducing structural durability.
Summary: Prefabricated concrete houses are suitable for scenarios prioritizing efficiency and cost, but strict control over joint quality is essential; in rural self-built house construction, supervision should focus on concrete mix ratios, grades, and vibration processes to avoid safety hazards caused by cutting corners.
