Fiber-Reinforced Powders for Construction
Efficient Testing of Glass and Carbon Reinforcement
Reinforcement made from fiber-reinforced polymers (FRP reinforcement) for the textile reinforcement of concrete is growing in popularity. However, for the tensile tests required for quality assurance, clamping is not generally suitable due to the sensitivity of the high-performance fibers. The alternative – namely bonding fiber strands in sleeves – is extremely time consuming, and is therefore unsuitable for relatively large test series. A new development shows how glass and carbon reinforcement can be quickly and efficiently tested using hydraulic jaws.
High-performance fibers are used for the textile reinforcement of concrete. They are highly brittle and,those made of carbon are highly sensitive to lateral pressure. When clamped directly with steel jaws, the serrations on the jaw surfaces would damage the filaments. At the same time, the fibers undergo a sudden change in strain at the transition to the clamping region due to the uniformly distributed clamping pressure.
Reducing the Clamping Pressure
solidian GmbH, Albstadt, Germany, together with ZwickRoell, Ulm, Germany, has developed a solution based on a parallel clamping hydraulic wedge grip. The new grip inserts protrude several centimeters out of the sample grip and thereby reduce the severity in the transition region by only applying the clamping pressure indirectly.
A special compensation layer, comprising a thermoset polymer with corundum filling is also used. It additionally reduces the clamping pressure in the transition region.
Comparative tests on the new sample grip, against fiber strands conventionally bonded in sleeves, showed no significant differences.
ZwickRoell GmbH & Co. KG
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