Elevated slab pours are a crucial aspect of construction that require careful planning and execution. This guide covers the essential steps and considerations to ensure a successful concrete pour for elevated slabs.
Pre-Pour Preparations
Before the actual pour, several preparations must be made to ensure everything goes smoothly:
1. Slab Gauging and Elevation
- Confirm that the slab is properly gauged and shot to the correct elevation.
- Assess the expected deflection of the deck and determine if riders can be used or if walk-behinds are necessary.
2. Deck Inspection
- Ensure that the deck is installed and inspected by a third-party inspector.
- Verify that all safety cables are in place before allowing personnel on the deck.
3. Nelson Studs and Steel Accessories
- Check that all Nelson studs are installed and inspected.
- Confirm that all necessary steel accessories, such as DBAs and vent plates, are in place and inspected.
4. Rebar and Bolster Chairs
- Ensure that all wire rebar is installed and properly supported on bolster chairs, elevated off the deck.
5. Block Outs and Floor Drains
- Consult with the project manager and engineer regarding any required block outs in the slab.
- Install all floor drains before the pour to avoid costly post-pour adjustments.
6. Expansion Joints and Re-Entry Bars
- Confirm that all expansion joints are installed.
- Check that re-entry bars are placed around outside corners to control cracking.
7. Benchmarking
- Have a surveyor establish benchmarks on columns to check edge angles and ensure proper installation heights.
Weather Considerations
1. Temperature Management
- If temperatures are expected to drop below freezing, consider tinting the building below the pour to maintain heat under the slab.
- Discuss with your supervisor about using additives for cold weather pours.
2. Concrete Ordering
- Order concrete several days in advance, especially for lightweight mixes, which may require more than a week for proper preparation.
- Ensure a quality control (QC) person from the concrete company will be on-site during the pour.
Logistics and Equipment
1. Scheduling Inspections and Equipment
- Schedule third-party inspections a few days prior to the pour.
- Order the concrete pump at least a week in advance, ensuring it meets the project specifications (e.g., using a five-inch hose for lightweight concrete).
- Arrange for light towers to be set up the night before the pour.
2. Access and Washout Areas
- Plan for safe access for trucks and pumps on and off the site.
- Designate a washout area that can accommodate multiple concrete trucks to prevent bottlenecks.
Day of the Pour
1. Final Checks
- On the morning of the pour, verify the first concrete truck ticket to ensure the mix matches what was ordered, including any additives.
2. Monitoring During the Pour
- Monitor the area below for any holes that may have been missed and need patching before the concrete sets.
- Ensure the third-party inspector is sampling the concrete and that any issues are communicated to the QC personnel.
3. Finishing the Concrete
- Once bleed water is off, begin finishing the concrete. Use walk-behinds if required by the engineer.
- After finishing, apply the sealer as discussed in the pre-pour meeting.
4. Covering and Heating
- If necessary, cover the slab and add heat underneath to maintain the desired temperature.
Conclusion
Following these steps will help ensure a successful elevated slab pour, leading to a well-finished floor ready for the next phase of construction. Proper planning, inspections, and communication are key to avoiding costly mistakes and ensuring quality in the final product.
