Customized rental of construction steel formwork: How to prevent and deal with loose joints in steel formwork?

1、 Preventive measures
1. Optimization during the design phase
Reasonable segmentation: Design templates based on structural dimensions to reduce the number of joints and avoid joints located in stress concentration areas (such as corners).
Reserved tolerance: During template processing, reserve 1-2mm of joint allowance to prevent gaps caused by thermal expansion, contraction, or installation errors.
Use standard parts: Prioritize using standardized templates (such as P3015, P6015) to ensure seam alignment.
2. Material selection and processing
Template flatness: Check the flatness and straightness of the new template (error ≤ 1mm/m), and repair or eliminate deformed or corroded templates.
Sealing material: stick double-sided foam tape, rubber waterstop or sponge tape (3~5mm thick) at the seam to enhance the sealing.
Edge rib reinforcement: Weld reinforcement ribs to the edges of the template to prevent warping and deformation during assembly.
3. Construction process control
Installation sequence: Assemble layer by layer from bottom to top, use a ruler to check the flatness of the joints, and ensure that adjacent templates are tightly fitted.
Specification for connectors:
U-shaped card: spacing ≤ 300mm, staggered arrangement to avoid missing cards;
Bolt fixation: The spacing between through wall bolts or split bolts should be increased according to design requirements (especially at corners);
Fixture assistance: Use steel fixtures to temporarily reinforce the joints.
Corner treatment: The internal and external corner templates need to be locked with the flat template, and L-shaped angle steel or special connectors should be added at the joints.
4. Quality inspection
Joint inspection: Use a feeler gauge to check the joint gap (should be ≤ 1mm), and adjust or fill the sealing material in areas that exceed the tolerance.
Trial assembly acceptance: Conduct template trial assembly before formal pouring, simulate concrete lateral pressure testing, and observe whether there is any leakage of grout.
2、 On site handling measures for loose joints
1. Emergency treatment of slurry leakage
Temporary sealing: When leakage is found, immediately fill the gap with wooden wedges, cement mortar or quick setting gypsum, and apply tape on the outer layer to prevent expansion.
Reinforcing support: slant support or steel clamp shall be added at the leakage part to prevent the formwork from further displacement.
2. Quality repair after demoulding
Surface repair: For honeycomb and rough surfaces caused by grout leakage, after chiseling away loose concrete, repair with high-strength mortar or epoxy resin.
Structural reinforcement: If grout leakage causes exposed steel bars or section loss, grouting or carbon fiber reinforcement shall be carried out according to design requirements.
3、 Long term improvement suggestions
Template maintenance:
Clean the residual concrete at the joints after each demoulding, repair the deformed edges and ribs, and apply anti rust oil.
Process upgrade:
Using BIM technology to simulate template joint positions and optimize layout design;
Introduce new sealing materials (such as silicone sealant, polyurethane foam strip).
Personnel training:
Regularly provide template installation specification training to workers, with a focus on explaining joint processing techniques.
4、 Key points for seam processing in different scenarios
Key points of scene seam processing
Vertical joints of high-rise shear walls are reinforced with U-shaped clamps, and angle steel is added at corners
The inner and outer sides of the circular joint of the bridge pier column are double sealed with waterstops and bolts
Customized heteromorphic structures with heteromorphic templates to reduce seams, with partial use of wooden templates for transition
Paste 3mm thick double-sided adhesive tape at the joint of plain concrete to ensure that there are no traces after demoulding
summarize
The core solution to the problem of loose joints in steel formwork is "prevention first, treatment as a supplement":
Prevention: Reduce joint problems from the source by optimizing design, standardizing construction, and conducting strict inspections;
Handling: Quickly seal the leakage of grout, and repair it in a targeted manner after demoulding to avoid affecting the durability of the structure;
Improvement: Combining technological upgrades and personnel training to enhance the standardization level of template construction.