Tensile test DIN 488 Reinforcing steel / reinforcing steel
Production / Quality Control DIN 488
Concrete as a building material generally has a very high compressive strength but low tensile strength. To compensate for this, concrete is reinforced. Reinforcing bars are poured into the liquid concrete. Diameters of 5 - 60 mm are typically used. The smaller diameters are used to produce steel mesh for surface application. The most common standards for these products are DIN 488, ASTM A370, ISO 15630 (..) and ACI 318. These standards contain the test requirements for determining the specific tensile strength (and bending properties).
Typical characteristics of tensile test DIN 488
- Reh / Rp0,2 / Rm based on nominal diameter
- monitoring of cross-sectional deviation
- high demands on data filtering + statistics
- Monitoring Re (ReH / Rp0,2): > 500 MPa
- Monitoring tensile strength Rm: > 550 MPa)
- Monitoring uniform strain Ag, Agt: > 8%
- Yield strength ratio Rm/Re: > 1,05
download method
Depending on the production range / diameter, the following methods are available for testing the reinforcing steel: tensile testing machines with capacities from 50 kN to 1200 kN. The most commonly used Tensile testing machine has a maximum force of 200 kN – type QUASAR 200. GALDABINI Tensile testing machines are equipped with advanced technology from European manufacturers: control and measurement electronics from BECKHOFF, spindles from BOSCH REXROTH, electrics from PHOENIX, etc. The quality classes for force measurement and strain measurement (quality class 1) required for testing reinforcing steel are met and exceeded by the equipment: force measurement from 1/100 of the nominal load, quality class 0,5% (from 1/500 of the nominal force, quality class 1).
The clamping of the reinforcing steel can be carried out with relatively inexpensive wedge clamps as the strengths are relatively low (max. approx. 750 MPa) and the teeth of the clamping jaws can penetrate well for an initial grip. These clamps / clamping jaws can be used for a long time as only a small amount of wear occurs on the sharpness of the clamping jaws. These clamps are also ideal for this task as clamp breaks / sample breaks outside the measuring length (outside the cutting edges of the extensometer) should be avoided.
To determine the E-modulus and the uniform strain Ag / Agt, which is very important for this test, strain gauges with a relatively long measuring path are required. A particular challenge for these is that the strain gauge blades must grip the irregular surfaces well. The MFA20 clamp-on strain gauge is particularly inexpensive and well suited (measuring path 20 mm - special blade arrangement for reinforcing steel). The MICRON extensometer is well suited and very convenient, as in "all" cases measurements are taken with an initial measuring length of 100 or 200 mm. The ECM type strain gauge (multi-channel strain measurement) is particularly suitable.
Since the wires and reinforcing steel bars are often covered in scale, covering the clamping jaws to protect them from dirt is strongly recommended. Nevertheless, regular clamping jaw maintenance (thorough removal of scale absorbed into the lubricating grease and subsequent re-greasing) is strongly recommended.
The LabTest testing software is particularly suitable for tensile testing according to DIN 488, among other things. In this software you will find ready-made test methods that can be modified for individual use. It is important that the test method supports the determination of the cross-section using the weight method and the connection of a scale. In addition, the LabTest testing software is equipped with a database filter system and particularly suitable statistics.
The GADALBINI equipment guarantees exact results and good repeatability. Your expectations for efficient testing are met and exceeded. Convince yourself of the equipment and visit us at one of our numerous customers or in our demo laboratory in Langenfeld (near Düsseldorf / Cologne).
