Testing large rebar sizes up through #11 (36) can require loads above 700 kN (160 kip). For testing this range of rebar, we selected a hydraulically powered universal testing system (
Model 1000HDX). This SATEC
™ Series frame provided the capacity we needed (1000 kN or 220 kip) and several nice options for testing rebar of this size. It's verifiable range down to 1/500th of capacity allows this machine to be used for testing smaller #3 rebar sizes as well.
We used the frame's open front, inhead wedge grips and a set of V-grooved jaw faces to secure the round rebar sample. The inhead grips allowed us to test up to full machine capacity. The jaw faces we selected were constructed from shock- resistant tool steel with a coarse tooth pattern. We've found that 8 to 20-teeth per inch works well for testing rebar. The coarse tooth pattern is necessary to bite into the irregular surface of the rebar samples and prevent specimen slippage. In contrast, we've found that a fine tooth pattern quickly becomes loaded with scale and debris. The jaw faces also include a mechanical stress relief on the initial portion of the tooth face to prevent premature failures.
To capture specimen strain during the test we used an extensometer specially designed for rebar testing. This extensometer is designed to be clamped to the irregular surface of rebar samples and supported the typical rebar gauge length of 200 mm (8 in). These extensometers are available in averaging and non-averaging styles and with other gauge lengths.
Finally, we used the tension template in Partner™ software to set up the test. The software prompted us for the test control, speed, break sensor, and results we needed.