Category:1036 Reinforcing Steel for Concrete: Difference between revisions

This article establishes procedures for inspecting and testing reinforcing steel for use in Portland cement concrete. Refer to Sec 1036 for MoDOT’s specifications.

For Laboratory testing and sample reporting procedures, refer to Laboratory Testing Guidelines for Sec 1036.

1036.1 Procedures

The methods of inspecting and accepting reinforcing steel are described in the following paragraphs. Steel is accepted on the basis of the PAL program. The manufacturer of the steel must be on the current Pre-Acceptance List.

1036.1.1 Inspection at a Construction Jobsite

Confirm that the steel is tagged with a PAL I.D. number. Confirm that the AASHTOWARE Project (AWP) record for the steel is representative of the material at the jobsite. When directed by Construction and Materials, the characteristics of the coating of coated steel may be determined in the field and a sample for flexibility of coating or for characteristics of uncoated steel may be obtained for submission to the Laboratory as indicated in EPG 1036.2.1 Reinforcing Steel, Dowel Bars, Mechanical Bar Splices and Cold Drawn Wire and Welded Wire Fabric and EPG 1036.4.2.2 Field Inspection. No Mill Test Report is required at a construction jobsite. When the characteristics of the material are suspect and a sample is obtained and submitted to the Laboratory for testing, Construction and Materials should be notified. Construction and Materials will obtain a mill test report from the shipper if necessary.

1036.1.2 Inspection at a Fabricator

A fabricator is any entity that incorporates steel into a product used for highway construction.

1036.1.2.1 Precast Plants and Similar Facilities

Uncoated and Epoxy coated steel are both inspected as follows. Confirm that the fabricator has obtained a PAL I.D. number for the steel. Confirm that the AWP record for the steel is representative of the material held by the fabricator. When directed by Construction and Materials, or when the characteristics of the material are suspect, a sample may be obtained as indicated in EPG 1036.2.1 Reinforcing Steel, Dowel Bars, Mechanical Bar Splices and Cold Drawn Wire and Welded Wire Fabric. The fabricator should have a Mill Test Report on file for all steel given a PAL I.D. Number. The fabricator's filing process should clearly connect the PAL I.D., the steel, and the documentation. Typically this is done with the heat number, but the fabricator may use any rational process. If the fabricator has non-PAL steel for non-MoDOT work, the material must be clearly marked or segregated.

1036.1.2.2 Epoxy Coating Plants

Typically a coating plant does not obtain a PAL I.D. for steel until it has been coated and is ready to ship to a jobsite. If the coated steel will be shipped to another fabricator, no PAL I.D. is required. When directed by Construction and Materials, or when the characteristics of the material are suspect, a sample of steel may be obtained as indicated in EPG 1036.2.1 Reinforcing Steel, Dowel Bars, Mechanical Bar Splices and Cold Drawn Wire and Welded Wire Fabric. The fabricator should have a Mill Test Report on file for all steel destined for MoDOT work. The fabricator's filing process should clearly connect the steel and the associated documentation. Typically this is done with the heat number but the fabricator may use any rational process. If the fabricator has non-PAL steel for non-MoDOT work, the material must be clearly marked or segregated.

Uncoated steel is inspected as follows: Routine sampling and testing of uncoated steel at an epoxy coating plant is for the purpose of quality assurance of the steel manufacturer. Samples are typically taken from a coating plant when the coater is more convenient than the steel mill.

Coated steel is inspected as follows: The characteristics and the properties of the coating are to be determined while at the fabricator as indicated in EPG 1036.4.2.2 Field Inspection. The fabricator's quality control process and records are to be reviewed.

1036.1.3 Inspection at a Mill

Typically a steel mill does not obtain a PAL I.D. for any steel. Only when the mill ships steel directly to a MoDOT jobsite is a PAL I.D. required. When directed by Construction and Materials, or when the characteristics of the material are suspect, a sample of steel may be obtained as indicated in EPG 1036.2.1 Reinforcing Steel, Dowel Bars, Mechanical Bar Splices and Cold Drawn Wire and Welded Wire Fabric. The mill should have a Mill Test Report on file for all steel destined for MoDOT work. If the mill produces or has non-PAL steel for non-MoDOT work, the material must be clearly marked or segregated.

Review the quality control records to determine whether failed material is produced and its disposition. Check for trends in the test results as would indicate whether the mill is capable of consistent production that is reasonably within the specification ranges. Confirm that the mill is capable of matching documentation with output from production to shipment.

1036.2 Exceptions, Mill Test Reports, Sampling and Record Keeping

Material must be inspected as the type or grade for which it is manufactured. If the steel does not meet the requirements of the specification to which it is manufactured, it may not be substituted for the next lower class. For instance, Grade 60 steel failing to meet Grade 60 requirements is not to be substituted for use as Grade 40.

ASTM A706 steel may be substituted for Grade 40 or Grade 60 provided that the mill certifications indicate that the A706 steel meets all requirements of AASHTO M31. Of specific concern is that the tensile strength meets the minimum required. Notify Construction and Materials if the substitution is made on PAL material.

Welded wire fabric for concrete pavement shall be furnished in mats of the size and design shown on the plans. It will be permissible to furnish longitudinally hinged wire fabric for sheets of a required width of 8 ft. or greater. The hinge shall be made by looping the transverse wires around a longitudinal wire, and shall be capable of developing the full strength of the transverse wire. The hinge shall be located within one foot of the center of the width of the sheet. All steel wire fabric shall be free from dirt, paint, oil, grease, thick rust and other foreign substances. Thin powdery rust need not be removed.

A mill test report showing complete physical tests is required for all reinforcing steel. The mill test report shall be retained by the shipper of the steel and a copy made available to the inspector upon request. The mill test report for steel bars shall also show the results of complete chemical tests. The mill test report shall be compared against the requirements of the proper AASHTO Specification to ensure contract compliance.

1036.2.1 Reinforcing Steel, Dowel Bars, Mechanical Bar Splices and Cold Drawn Wire and Welded Wire Fabric

When a sample is requested, the steel shall be sampled, submitted to the Laboratory for testing with a copy of the mill test report except as indicated (above), and documented through AASHTOWARE Project (AWP). Samples shall consist of the following:

1036.2.1.1 Reinforcing Steel, Dowel Bars, Mechanical Bar Splices and Cold Drawn Wire

When requested, a sample of reinforcing steel representing a heat, size or grade; or cold drawn wire shall consist of six pieces for the steel properties. For uncoated reinforcing steel, when possible, three bars, one each from three bundles will be sampled, with two pieces cut from each uncoated bar. The pieces should be labeled as 1A and 1B from the first bar, 2A and 2B from the second bar, and 3A and 3B from the third bar. Epoxy coating properties (when required) shall be field tested. Samples submitted to the laboratory for epoxy coating shall consist of three pieces cut from three bars, with each bar from a different bundle, when possible. Mechanical bar splice samples shall consist of three splices. If the first splice fails, the remaining two splices shall be tested. Both additional splices must pass for approval. Mechanical bar splice samples shall have 12 ± 1 in. (300±20 mm) of reinforcing steel extending from each end of the splice. Samples of cold drawn steel wire and reinforcing steel bars shall be of the length shown for the appropriate bar size and test shown in the following table.

1036.2.1.2 Welded Wire Fabric

When requested, wire to be sampled for Laboratory testing is to be field measured for size prior to sampling. Each wire across the width of fabric is to be measured. The manufacturer may use over-sized wire in the fabrication of welded wire fabric, but no under-sized wire. The size differential shall not exceed two "W" size increments on sizes W8 and smaller and four "W" size increments on sizes larger than W8. "W" sizes referred to are those shown in AASHTO M 32. In all cases where over-sizing exists, the fabric shall be identified and used as that originally ordered or offered for use. Field measurements should be listed in the remarks associated with the Basic Sample Data tab in AWP when submitting the sample. A sample of welded wire fabric shall consist of one piece representing the full width of the fabric and not less than 24 in. (600 mm) long, measured in the direction of the longitudinal wires. It will be permissible to cut a sample into sections approximately 3 ft. (900 mm) wide, for convenience in shipping to the Laboratory. When samples are to be reduced into such sections, the cuts should be made in transverse wires approximately at the midpoint between the two adjacent longitudinal wires.

A producer may fabricate welded wire fabric, from cold drawn wire, at their facility for their own consumption. For example, a reinforced concrete pipe producer fabricates welded wire fabric, from cold drawn wire, for use in a reinforced concrete pipe. The inspector shall be responsible for sampling the welded wire fabric to ensure that the producer’s fabrication process does not affect the wire’s compliance. Samples shall be taken and submitted to the Laboratory for testing as described in EPG 1036.2.1.2 Welded Wire Fabric. The inspector shall also verify that the wire was obtained from an approved PAL source. Non-compliance of the fabricated welded wire fabric will not be considered a PAL strike, but may affect the producer’s qualification to supply their product to MoDOT.

When reporting welded wire fabric in AWP, the material code corresponding to the larger of the two wire sizes shall be chosen. The details of the welded wire fabric, including both wire sizes and the wire spacing (if known), shall be recorded in the Remarks of the sample record. A different sample ID shall be given for each different configuration of welded wire fabric, even if the larger wire size is the same. This reporting procedure shall be used at all times; when taking and reporting samples for Laboratory testing and when reporting welded wire fabric to a contract.

1036.3 Sample Record

If Laboratory samples are obtained, the Laboratory will record the test results in AWP. The Basic and Additional Sample Data tabs shall show all pertinent information regarding the material including heat number. Appropriate remarks, as described in EPG 106.20 Reporting, are to be included to clarify conditions of acceptance or rejection.

Plant Inspection Record. Information regarding inspection of a mill will be recorded in AWP as a sample record with the code 0106XXPAL and as indicated in EPG 106.1 Source of Supply and Quality Requirements.

1036.4 Epoxy Coated Reinforcing Steel

This article establishes procedures for inspecting epoxy coated reinforcing steel for use in Portland cement concrete. Refer to Sec 1036.5 for MoDOT’s specifications.

Epoxy coated reinforcing steel should only be accepted if coated by one of the qualified coating plants designated on PAL. A PAL epoxy coating plant should be inspected once a month when the plant is providing material for MoDOT work. At the time of inspection of the plant the inspector should confirm that the plant is producing to meet MoDOT specifications however, it is not necessary that the production be specifically for MoDOT work if the process used is typical of that employed for MoDOT work.

New epoxy coating plants will be added to PAL by Construction and Materials on the basis of a standard PAL application except that the coating material to be used must be indicated and must be an approved material. Epoxy coating material shall be approved based on the compliance of test results with ASTM A775/A775M. Tests on epoxy coating material shall be performed by an acceptable agency. A report summarizing the results of all tests and bearing the signature of the testing laboratory shall be submitted to Construction and Materials for review, along with completed copies of the New Product Evaluation Form and GS-13 Form 4. The manufacturer will also provide at least one compatible field patching material.

1036.4.1 Apparatus

(a) Magnetic gauge, reading range 0-40 mils (0-1000 μm).

(b) Holiday detector, Tinker and Rasor Model M/1 or equivalent

(c) File or knife to remove coating for holiday detector connections

(d) Pictorial surface preparation standard.

1036.4.2 Procedure

1036.4.2.1 Plant Inspection

Uncoated steel should be from a PAL source. Surface preparation should be checked to ensure compliance with SSPC-SP10, near white finish. Periodic checks should be made to ensure the temperature recommendations of the epoxy powder manufacturer are being followed and the coating is properly cured. The epoxy powder must be on the Qualified Epoxy Powders list.

1036.4.2.1.1 Coating Film Thickness

Coating film thickness may be checked with a magnetic gauge as soon as the bars have cooled to handling temperature. Readings should be taken on a representative number of bars from the total production. The inspector may vary the number to be tested depending upon plant production and difficulties encountered in the coating process. Two thickness readings should be taken on each side of the bar at three locations to give twelve readings per bar. The average of these readings should be recorded as the coating thickness on the bar tested. The inspector should try to use the smooth area near bar markings whenever possible and hold the gauge firmly on the bar to ensure accurate readings. Unusually high or low readings should be checked again and not recorded if gauge error due to surface irregularities is suspected. Readings should be recorded to the nearest 0.1 mil (2.5 μm) and reported to the nearest whole mil (μm). Thickness determinations on all bars of a given size should be averaged to give the reported thickness for an inspected lot. An inspected lot may be considered as the amount of steel available for inspection at the time an inspection is performed.

1036.4.2.1.2 Continuity

Continuity of coating may be checked on the same bars used for coating thickness determinations. Attach the lead wire of the holiday detector to any location on the bar where the coating has been removed down to bare metal. Pass the wet sponge attached to the inspection lead of the detector over the coated surface. Make at least one pass in each direction along the length of the bar to ensure contact on both sides of bars with sharp or rough deformations. Record the number of holidays per bar length. Divide the total per bar by its length in feet (m) to determine compliance with the maximum allowable of one per foot (3 per m). If the coater has an in-line holiday detector, the coated steel should be checked periodically with a portable detector to ensure its accuracy.

1036.4.2.1.3 Flexibility

Flexibility of coating tests should be performed as part of a plant inspection.

1036.4.2.1.4 Plant Inspection Record

When epoxy coated reinforcing steel is inspected at the coating plant, AWP shall be used to document the inspection. The inspector is to show complete information related to the inspection. A material code, 0106XXPAL, is provided to track plant inspections.

In addition to the sample record documenting the plant inspection, a sample record shall be created for each size and grade of epoxy coated reinforcing steel using the corresponding material code. The record should contain test SAA006CD – Epoxy Coated Steel Tests, which will be used to record the following:

(a) Coating thickness average of all bars of each size rounded to nearest whole mil (μm).

(b) Holiday test results, maximum of one per ft. (3 per m).

(c) Brand of coating material.

(d) If there are any exceptions in the test SAA006CD or a need for any other additional remarks, they should be recorded in the Free Form Test.

1036.4.2.2 Field Inspection

The procedures described in the preceding paragraphs for coating film thickness and continuity tests apply also to field inspection. When directed to sample at a jobsite, select three bundles at random of each bar size from each load. If individual loads cannot be distinguished, every fourth bundle of each size may be selected. Take three bars from each bundle and perform thickness and holiday tests. If results are not within specification limits, double the number of sample bars should be taken. If ten percent or more of the bars tested fail to meet specification requirements, Construction and Materials should be notified of the circumstances of the failure. A quick survey of the entire lot consisting of random checks with the magnetic gauge and visual examination of the coating will usually ensure the material selected is representative. Once field tests have determined compliance with the holiday and coating thickness requirements, samples for steel properties and flexibility of coating should be taken.

Field Inspection Record. Test results obtained by a jobsite inspection, in addition to any appropriate remarks, will be recorded in a sample record specific to the material sampled with a reference to the original PAL I.D. assigned to the material by using the Link To function. If no test results are obtained, remarks may be posted to the Remarks or Disposition Remarks of the PAL I.D. record for the material.

1036.5 Certification

Regardless of where the epoxy coated steel is sampled and tested, the shipper should have available the following:

(a) Steel manufacturer's certified mill test report showing complete chemical and physical test results.

(b) Epoxy powder manufacturer's certification that the materials supplied the coating applicator conforms to the contract.

(c) Coating applicator's certification certifying that all materials used, the preparation of the bars, coating and curing were done in accordance with the contract and that no bar contains more than 1 holidays per ft. (3 per m).

(d) Coating applicator's specific test results of tests for coating thickness and flexibility of coating.

Typical certifications should be examined for compliance as part of a plant inspection. Method of filing and ability to track documentation of a particular shipment shall be to the satisfaction of the inspector. It is acceptable for a shipper to obtain the documentation listed above (from the manufacturer) at the time it is requested by the inspector if it is obtained in a timely fashion and can reasonably be tracked to the material shipped. Certification is not required at the jobsite.

1036.6 Repairing Bars

Patching should be performed in accordance with the coating manufacturer’s instructions and as described in Sec 710.3.3. It is not intended that patching material be used to cover extensive areas left uncoated during the initial coating process. Patching should be done sparingly on sheared or cut ends and damaged areas.