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| IMAGE CREDIT : LINKEDIN |
Column retrofitting works to enhance the load-bearing capacity of an existing column by extending its foundation as part of retrofitting works.
Here are the 10 steps to execute the retrofitting works :
Step 1: Surface Preparation (Chipping)
- Chip the existing concrete surface of the foundation using a mechanical chipping tool or hammer.
- Ensure removal of all loose, weak, and deteriorated concrete.
- Expose the reinforcement bars, if needed.
Step 2: Surface Cleaning
- After chipping, clean the surface thoroughly:
- First using a wire brush to remove dust and particles.
- Then use a blower (compressed air) to eliminate all remaining debris and fine dust.
Step 3: Drilling for Dowels
- Drill holes at the required depth and spacing for dowel bars as per structural drawings.
- Maintain proper hole diameter to match the bar size and ensure firm anchorage.
Step 4: Dowel Bar Installation
- Clean the drilled holes using brush and blower.
- Inject Hilti chemical anchoring material (e.g., Hilti HIT-RE 500 or similar) into the holes.
- Insert the dowel bars immediately before the adhesive sets.
- Allow adequate curing time as recommended by the manufacturer.
Step 5: Reinforcement Fixing
- Install the additional reinforcement steel for the foundation extension and column base as per approved drawings.
- Tie the bars properly using binding wire to maintain correct positioning.
Step 6: Formwork Preparation
- Erect the formwork around the foundation extension as per the required shape and dimensions.
- Ensure formwork is rigid, properly aligned, and free from any leakage points.
Step 7: Final Surface Cleaning
- Just before applying bonding agent and pouring grout, clean the surface once again:
- Use a blower to remove all loose particles, dust, or foreign material from formwork and concrete surfaces.
Step 8: Application of Bonding Agent
- Apply Cempatch SBR 100 (or equivalent SBR-based bonding agent) on the cleaned surface.
- Ensure uniform application on all old concrete faces that will come in contact with new concrete/grout.
Step 9: Grouting / Concrete Pouring
- Prepare the grout mix using:
- Renderoc LA Xtra (non-shrink cementitious grout)
- Clean aggregates as specified
- Measured quantity of water to achieve the required flowability.
- Mix thoroughly using a mechanical mixer.
- Pour the grout carefully into the formwork, ensuring full compaction and no voids.
- Use rodding or light vibration if needed.
Step 10: Surface Curing
- Begin curing after initial setting of the grout/concrete.
- For curing we will use burlaps and put water on it 3 times in a day
Final Notes :
All materials and procedures must follow project specifications and manufacturer guidelines.
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