Concrete

Purpose and Scope

The purpose of this procedure is to ensure that the various components of a concrete pour, including post tensioning, have been installed as per the relevant project documentation, Australian Standards and in compliance with other Hansen Yuncken HYer Standards and procedures.

The scope of work includes all formwork, reinforcement and prestressing tendons, supply, placement, and finishing of concrete elements. Concrete FRP (Formwork, Reinforcement, Pour) refers to concrete elements that are prepared and poured onsite. Requirements for Precast elements are documented in the Precast and Tilt-Up Procedure.

Responsibilities

Project Manager

• Ensuring design changes are assessed for constructability risks.
• Ensure any design constructability risks are assessed, controlled, and documented in the Project’s Risk Register.
• Ensuring any constructability risks identified are communicated to workers performing the work and the HY project team.

HY Project Team

• Obtaining and reviewing project documentation, drawings, and specifications.
• Managing workflows to document RFIs and design changes.
• Managing the project’s document registry and communicating documentation to relevant parties.
• Communicating requirements for submittals, warranties, and inspection and test plans to Subcontractors and other parties as applicable.
• Ensure nominated subcontract users are registered in the QA platform and invited to the Project Profile.
• Ensuring relevant quality control pre-work checks are complete prior to starting works.
• Ensuring any applicable hold and witness points are in place and adhered to.
• Receiving and controlling submittals, warranties, and inspection and test plans.

Subcontractor Supervisor

• Ensure personnel responsible for using the QA platform are registered and have means to access the platform via mobile or desktop devices.
• Ensuring relevant quality control pre-work checks are complete prior to starting works.
• Ensuring any applicable hold and witness points are adhered to.
• Providing any required submittals, warranties, and inspection and test plans.

Quality Verification 

Hansen Yuncken predominantly utilises Autodesk platforms (BIM360 and ACC) to carry out quality control checks and verifications. Subcontractor supervisors or nominated representatives must have a registered Autodesk account and be invited onto the Project Profile by the HY project team. 

The Concrete – FRP Checklist (or Formwork, Reinforcement, and Concrete Checklists) in the QA platform is to be completed prior to and throughout the relevant stages of works.  HY representatives are responsible for completing the header and site preparation sections. The subcontractor representatives are responsible for completing their respective sections respectively. All hold points must be adhered to and verified by the HY representative to proceed.

Guidance on the use of software for Subcontractor users can be accessed via the Onboarding Induction and Training Procedure.

Note: Defence Projects and select Government Projects may have unique requirements regarding Quality Control and the use of software packages to carry out verifications.  The agreed methods and software packages will be determined at Project Commencement considering the specific project needs and client requirements.

Preparation

Project drawings and specifications will detail the locations and requirements of the concrete associated materials to be used in the installation process. The latest revisions of drawings and specifications are to be referenced for the works, which are to be provided to the subcontractors carrying out the works.

Weather is to be considered when planning concrete pours. For concurrent concrete deliveries, trucks are to be scheduled to arrive on time, with the correct amount of concrete, and mix is poured on time to ensure there are no delays which can result in a cold joint. If delays occur during the pour, the concreter is to maintain a ‘wet edge’ to avoid cold joints if necessary. Deliveries are to be managed in accordance with the Transport and Deliveries procedure.

Determine the curing method or the requirement for accelerators before commencing concrete pours. It is essential to verify this with the engineer prior to implementation, as well as the inclusion of any additives or admixtures in the concrete mix, as these substances can influence the workability of the concrete and alter the curing time. Ensure there are enough products or materials on site for the area. Any deviations from the specification should be approved by the engineer prior to implementation.

Approvals 

Submittals, samples, and materials are to be identified, reviewed, and approved by the respective responsible parties in accordance with project specifications prior to works beginning. Any changes are to be captured via appropriate channels for the project (e.g., Aconex Workflow) and communicated to workers. 

The concrete installation and associated works are to be verified in accordance with the project drawings and specifications.  The following items must be confirmed:

1. Concrete mix design has been reviewed and approved by Engineer
2. Curing compound has been reviewed and approved by Engineer
3. Subcontractors ITP

In-Ground Pour Preparation

The following items are to be verified for in-ground concrete pours:

1. Footings have been founded into the required material, depth, and safe bearing capacity as per the project specifications.
2. The subgrade has been prepared per specifications and accepted.
3. The subbase has been finished within the required tolerances to the specified grade and level.
4. Excavations for drainage and service trenches have been backfilled in accordance with AS 3798.
5. A vapour barrier has been installed in accordance with the
6. Services pits are square, in the correct location and correct reduced level (RL).
7. Cast-in hold down bolts have been installed correctly.

Formwork

Formwork edges are to be adequately propped to prevent movement during concrete pours.

The following formwork items are to be verified:

1. Formwork is of specified type – surface will achieve the specified class of finish.
2. Size and spacing of framing is to be in accordance with approved design.
3. Props are vertical and aligned with back-propping on floor below if applicable.
4. Sole plates are bearing on solid surfaces.
5. Forms have been set to the finished surface level within the specified tolerances.
6. Edge board set out is correct.
7. Formwork is straight, plumb, and stable.
8. The required edge rebates, blackouts, set downs and cast in items are installed.
9. Beam widths and depths are in accordance with design.
10. Formwork edges and corners have been adequately sealed to prevent leakage.
11. Forms have been coated with oil or an approved release agent.

Reinforcement

The following reinforcement items are to be verified:

1. Bars or mesh are of correct size, tied in position and lap length correct.
2. Reinforcement is free from excessive rust or corrosion.
3. Bar chairs in position and correct cover as specified.
4. Reinforcement around cast-in items, penetrations and block outs has been installed in accordance with the design.
5. Mesh is pre-cut at saw cut joints and not overlapping.
6. Expansion joint filler is installed to walls and columns where specified.

Post Tensioning

The following post tensioning items are to be verified:

1. Anchorages are securely fixed and anti-burst is installed.
2. Duct position and alignment is correct.
3. The correct type/number of strands have been installed.
4. Dead ends are installed.
5. Tendons are installed to the correct profile and supported by chairs.
6. Grout hoses are installed with anchorages sealed.
7. The initial stress has been carried out in accordance with the specification.
8. The concrete test results have reached the minimum required strength per the specification.
9. The full stress has been carried out in accordance with the specification.
10. The extensions have been recorded and approved.
11. The tendons have been cut, sealed, and grouted.

Concrete Supply/Placement

Prior to pour, ensure the deck is free of debris, objects, and pooling water. If reasonably practicable during pours, representatives from the Formworker and Service trades (if necessary) are to be on site and available during the pour to rectify issues with formwork block outs or service conduits which may shift or become damaged during the pour.

The following items are to be confirmed at the commencement and/or completion of the pour.

1. The concrete ordered and used is of the approved mix design.
2. The concrete slump meets the specification.
3. Water has not been added to the concrete on site (unless approved by engineer/tester).
4. The concrete has been placed to the specified RLs (within allowed tolerances).
5. Concrete is adequately vibrated.
6. The joints as provided are in accordance with the specification.
7. Falls to floor waste are achieved with correct grade and level
8. The concrete surface finish is in accordance with specified class and colour control requirements.
9. Correct volume of curing compound has been used.

Specifications and Compliance 

Current Project Specifications are to be used to confirm all approvals, samples, and submittals required for the project. Project Specification requirements are to be entered into the Project’s Compliance Schedule. 

The following approvals/samples may be required: 

• Concrete mix design has been reviewed and approved by the Engineer.
• Curing compound has been reviewed and approved by the Engineer.
• Subcontractors ITP

The following supporting documentation or submissions may be required from the subcontractor: 

• Subcontractor completed checklist/QC records or ITP including inspection reports
• Compressive Test Report
• Concrete delivery dockets
• Curing application verification
• Pour plan
• Final RL survey
• Equipment Calibration Certificates

Hold/Witness Points to be adhered to throughout works:

• Inspection – Base or subgrade before covering.
• Inspection – Membrane or film underlay installed on the base or subgrade.
• Concrete mix design has been reviewed and approved by Engineer.
• Inspection – Reinforcement / formwork / post tensioning / fixing or embedded items has been inspected and approved by Engineer or Building Surveyor as applicable.
• Curing compound has been reviewed and approved by Engineer.
• Verify approved joint sealer has been applied as specified to locations.
• Confirm all services trades have verified that all in-ground, penetrations, block outs, cast-in have been provided.

Definitions

ITP – Inspection and Test Plan

RFI – Request for Information

RL – Reduced Level

References

• AS 1012 – Methods of testing concrete Sampling of concrete
• AS 1379 – Specification and supply of concrete
• AS 3600 – Concrete structures.
• AS 3610.1 – Formwork for concrete Specifications.
• AS 3972 – General purpose and blended cements.
• AS 4663 – Slip resistance measurement of existing pedestrian surfaces
• AS 6669 – Plywood – Formwork
• AS/NZS 4671 – Steel for the reinforcement of concrete.
• AS/NZS 4672 – Steel prestressing materials General requirements
• ASTM C 1074 – Standard Practice for Estimating Concrete Strength by the Maturity Method.

Associated Checklists and Documents

• Concrete – FRP Checklist (Autodesk)
• Formwork Quick Guide