Quality Issues with Prefabricated Building Components

Quality issues with prefabricated building components mainly include the following categories, with specific manifestations and causes as follows:

Surface Quality Defects

The outer surfaces of prefabricated concrete components exhibit noticeable air holes, pitted surfaces, or even cracks. Main causes include the use of grease-based release agents, which reduce the adhesion of the concrete surface; inadequate cleaning of the mold table, leaving residues that affect concrete forming; insufficient vibration of the concrete, preventing the escape of internal air bubbles; failure to install reinforcing bars as specified in stress-concentrated areas such as door and window openings; and failure to reinforce components according to design requirements before lifting and transportation, leading to uneven stress and cracking.

On-site Stacking Issues

Prefabricated components are stacked haphazardly, with no spacers or misaligned spacers between layers, causing the components to crack under pressure. Core cause is the lack of on-site management, with no clear specifications for component stacking upon arrival, a lack of supervision and inspection mechanisms, and high variability in worker operations.

Lifting Misalignment Issues

Prefabricated wall panels deviate from their designed positions during lifting, affecting the overall structural integrity. Direct causes include failure to strictly position the walls according to control lines during installation, leading to cumulative errors; and quality issues with the components themselves, such as inconsistent thickness or deformation during processing, which increase installation difficulty.

Pipeline Omission or Misalignment

Omission or misalignment of pre-embedded pipes and fittings necessitates chiseling of the prefabricated panels during installation, damaging the component structure. Main causes include omission of pre-embedded pipes and fittings during component processing, or failure to install pipelines according to drawings, with a lack of process inspection.

Inadequate Grouting Issues

Inadequate grouting at the roots of prefabricated wall panels severely affects connection strength. Key causes include an unreasonable mix ratio of the grouting material, resulting in insufficient fluidity; blockage of grouting pipes or inadequate sealing leading to grout leakage; and failure of construction personnel to operate according to technical requirements, such as insufficient grouting pressure or failure to vibrate in layers.

Flat Panel Fabrication and Installation Issues

• Corner Panel Breakage: Corner positions are prone to breakage during transportation or lifting, with processing angle deviations or cracks at connections with cast-in-place sections. Causes include the thin thickness and large volume of corner panels, making them susceptible to internal bending forces during lifting; improper production and curing leading to angle changes; and inadequate connection between the cast-in-place formwork and the prefabricated section, with insufficient vibration.
• Laminated Panel Fracture: Cracking or fracture of the panel surface during transportation, with warping or chipping during processing. Causes include excessive span leading to compression during transportation and excessive deflection during lifting; improper production and curing causing panel deformation; and uneven application of release agents leading to mold adhesion.
• Exterior Wall Panel Insulation Layer Fracture: Detachment or fracture of the insulation layer. Core cause is the use of non-uniform insulation materials in "sandwich" components, resulting in insufficient bonding strength.

Connection Issues

• Inadequate Grouting: Difficulty in inspecting grout fullness during longitudinal connections, with blocked grouting holes. Causes include the invisibility of the internal situation during grouting, making fullness difficult to control; and imprecise production operations at the component factory, with inadequate on-site cleaning.
• Sleeve Connection Misalignment: Displacement of reinforcing bars and sleeves, with partial and complete misalignments. Main cause is the small sleeve aperture, with size inaccuracies due to machine or human factors during processing.
• Pipeline and Component Embedding Issues: Blockage or detachment of pre-embedded pipelines, and misalignment of pre-embedded components.