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Strengthening Concrete Silos in USA
Carbon Fiber Reinforced Polymer (CFRP)
Apply two layers of carbon fiber circumferentially along the silo wall, covering all crack areas and stress concentration sections, with a focus on reinforcing the lower and middle parts of the silo wall (the area with the greatest material-side pressure).
A small vertical concrete storage silo reinforcement project was undertaken. The silo, approximately 4 meters in diameter and 10 meters deep, was primarily used for storing granular industrial raw materials. Five years after its completion and commissioning, inspections revealed multiple circumferential micro-cracks in the silo walls and low concrete strength in some areas, posing a structural safety hazard.
For micro-crack areas, first apply epoxy grouting, then apply CFRP fabric to ensure the reinforcement layer and the original structure work together to bear the load.
Apply two layers of carbon fiber circumferentially along the silo wall, covering all crack areas and stress concentration sections, with a focus on reinforcing the lower and middle parts of the silo wall (the area with the greatest material-side pressure).
Crack Repair
Surface preparation: Grind the concrete surface of the silo wall with an angle grinder to remove laitance, loose layer and oil stains, exposing solid aggregate; for circumferential cracks with a width ≥0.2mm, inject epoxy sealant to complete crack sealing and repair.
CFRP bonding
① Apply primer: Mix the primer according to the specified ratio and apply it evenly to the treated silo wall surface. Proceed to the next step after the primer is touch-dry.
② Cutting and pasting: Cut the CFRP fabric to the silo circumference, leaving a 100mm overlap. Two people work together to paste the CFRP fabric onto the silo wall, using a rubber roller to roll it from the center outwards to remove air bubbles and ensure the fabric surface is flat and free of voids.
③ Layer bonding: Paste two layers of CFRP fabric. Each layer must be coated with impregnating adhesive to ensure the carbon fiber bundles are completely saturated.
Curing
After the reinforcement system has fully cured, apply anti-corrosion and protective adhesive to seal and protect the CFRP fabric and anchors. After construction is completed, test the CFRP fabric hollow rate (≤3%) by tapping and test the load-bearing capacity by pull-out. After acceptance, the silo can be put back into use.
