Testing of Sections and Reinforcing Steel

Sections made of various materials are rolled or drawn out of semi-finished goods such as billets or bars, and in many cases they are also welded from bar material. They are used in a vast number of applications, requiring a wide variety of mechanical tests. Together with the reinforcing steel and ribbed reinforcement bars (rebars) so vital to civil engineering they form a group of important structural materials, which in the case of concrete-reinforcing steel, are subject to regulatory control.
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Tensile Tests

Because concrete has high compressive strength but lower tensile strength, it is reinforced by embedding steel in it. Reinforcing steels are mainly produced in diameters from approx. 5 mm to approx. 60 mm. The smaller diameters are then further processed into mats or lattices before having concrete poured over them on site. Testing these ribbed steels poses a particular challenge because, apart from cutting to length, no further mechanical specimen preparation takes place. The necessary strain measurement at the specimen for accurate determination of the yield point is almost always determined with the makro extensometer. It accurately records the strain up to break without being affected itself. The makro extensometer is distinguished by

  • A high level of robustness for measurement up to break
  • Special knife edges at the tips of the sensor arms 
  • Automatic attachment and removal of the sensor arms to and from the specimen
  • Large diameter range
  • Fully integrated in the automatic test sequence
  • No manual operation needed
  • Optional automatic withdrawal from the test area

Flexure Tests

Flexure tests on reinforcing steel are used to test ductility. The specimen must not lose strength and no cracks must be detected on visual inspection. Various die radii and anvils are specified, depending on the standard, the bending angle as a rule being 90° or 180°. For this test Zwick supplies hydraulic testing machines and flexure test kits as per standards. If required two test areas can be installed on electro-mechanical testing machines and used for flexure and tensile tests, eliminating the need to modify the test arrangement.

  • Plug-in system for easy attachment of flexure test kit
  • Standard-compliant flexure test kits
  • Use of two test areas in one testing machine
  • Optional side working area   
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Shear Tests

The weld points of reinforcing mats and lattices are tested for shearing. This involves removing specimens from welded mats and lattices and placing them in special close-fitting specimen grips. Specimen grips used for this type of test must be accurately matched to the diameter and position of the ribbed wires in order not to influence the shearing forces. Zwick has decades of experience in this area and has developed a comprehensive range of accessories.
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Fatigue Tests

Reinforcing steels are required by the standard to have a defined fatigue strength, which must be verified. These fatigue tests are most quickly and economically performed using Vibrophores (resonance pulsators). The Zwick Vibrophore is an ideal solution for this application up to 600 kN. Specimens can be up to 36 mm in diameter; from 14 mm they must be grouted; a grouting device is available.
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Robotic Testing Systems

Reinforcing steel is produced in large quantities and must be continually tested for production monitoring. Zwick has developed automated systems in which specimens cut to length from rod material or separated from mats and lattices are loaded manually into magazines, after which they are tested completely automatically. Artificial aging at 100° C can also be integrated into this type of testing system. Cross-sections are measured with high accuracy and in accordance with standards and specimens can be sorted according to test result for later visual inspection.

  • Customized total solutions
  • Integration of all relevant tests
  • High availability
  • Useful options for forwarding fault reports.
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