Many standards govern rebar testing including: ASTM A370, ASTM A615, ASTM A996, BS4449 and EN 10002-1. The mechanical tests these standards outline can be demanding on operators and testing equipment. So, when testing large rebar samples - #14 (all grades) - we suggest using a single test space load frame in lieu of traditional dual test space styles. For this test we used a 1500KPX Model, which has a capacity of 1500 kN (337,500 lbf) and accommodates rebar specimens ranging in length from 400 mm to 700 mm.
The KPX load frame features a top-mounted hydraulic actuator which places the loading area at ground level. This significantly reduced our lifting requirements for loading the heavy rebar specimens. Additionally, we were able to perform both tension and bend tests on the rebar sample by adding compression adapters to the tension grips. This saved us change-over time because we didn’t need to use the overhead crane to remove the large, heavy tension grips. Adding the compression adapter and bend fixture took only a few minutes and simply involved tightening a few screws.
For the tension test we used hydraulic wedge grips because the initial clamping force reduced grip slippage on the uneven surface of the rebar. These hydraulic wedge grips accept rebar specimens from 10 mm (0.39 in) to 70 mm (2.75 in) in diameter. The grip jaws are vee-shaped with a custom-cut groove to accept the ribs found on rebar.
Finally, we used an automatic contacting extensometer to capture strain. The model we selected, an Auto X, has an adjustable gauge length from 10 mm to 750 mm (required for most rebar applications). It automatically clamps to the ribs of the rebar surface when a test is started and unclamps at a specified point during the test. The strain data can be used for required modulus and yield calculations.