Earthwork (Grading, Excavation and Filling, Foundations)

 

Asphaltic Concrete

 

Reinforcing Steel

 

Concrete Batch Plant

 

Concrete

 

Shotcrete

 

Pre-Tensioned Concrete

 

Post-Tensioned Concrete

 

Masonry

 

Structural Steel and

 

High Strength Bolting

 

Nondestructive Testing

 

Spray-Applied Fireproofing

 

Glu Lam and Truss Joists

 

Shear Walls and Floor Systems Used as Shear Diaphragms

SECTION 7 - PRE-TENSIONED CONCRETE

OBJECTIVE

Because the strength of materials used in prestressed construction is significantly higher than normal concrete construction, there has developed a strong quality control program by plant manufacturers. As a result, the purpose of pre-tensioned concrete plant observation is to verify the actual control program and check its effectiveness.

This objective can best be achieved by qualified special concrete inspectors performing the following duties under the direct supervision of the materials engineering laboratory.

OBSERVATION DUTIES

A. Documents

1. Review the approved plans, specifications, and approved shop detail drawings.
2. Verify that concrete mix designs, tensioning data, and calculations for stressing have been approved by the reviewing authority.
3. Verify that jacking equipment has been calibrated.

B. Mill and Plant Test Reports

1. Check conformance of all materials to project specifications. Verify steel mill test reports for prestressing steel and deformed bar steel. Verify mill markings and tags. Verify cement mill test reports and certification.
2. Check fabricator’s testing facility and reporting of tests performed under fabricator’s quality control program.

C. Sampling

1. Sample and deliver or ship to the laboratory for testing the following when independent tests are required by project specifications:
   1. Concrete aggregates
   2. Prestressing strand or wire
   3. Reinforcing steel
   4. Steel used for structural steel embedded items

D. Steel Fabrication of Embedded Items

1. Verify that qualified welders are employed to perform welding of structural steel using welding procedures qualified in accordance with AWS Structural Welding Code.

E. Pre-Placement Observations

1. Bed layout and form cleanliness.
2. Quantity and spacing of reinforcing and stressing steel.
3. Location of inserts and embedded items.
4. Profile of stressing steel.
5. Witness tensioning of prestressing elements, measure elongation of strand, and record gauge pressure.

F. Tests and Observation During Casting

1. Perform batch plant observations.
2. Conduct slump, air, and unit weight tests. Request adjustments as necessary.
3. Cast compression test specimens.
4. Observe placement and vibration of concrete in forms.
5. Observe finishing treatment.

G. Post-Placement Tests and Observations

1. Observe curing procedures, temperatures, and curing cycles.
2. Monitor compressive strength results for specified release strength.
3. Witness stress transfer.
4. Identify member by component and date cast.

H. Field Erection

1. Check members for damage during storage or shipment.
2. Check field installation and structural connections.

I. Reports

Submit written progress reports describing the tests and observations made and showing the action taken to correct nonconforming work. Itemize any changes authorized by architect/engineer. Report all uncorrected deviations from plans of specifications.

 

 

 

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