TORQ-TEST
TORQ-TEST
Purpose
The TORQ-TEST is used to evaluate the shear strength of
- Surface concrete
- The bond between carbon fiber reinforced polymer (CFRP) sheets or strips and concrete
- The bond between an overlay and concrete
Principle
A disc with an integral ring, 55-mm inner diameter and 75-mm outer diameter, is bonded to the surface using a rapid curing adhesive (GRA) and is used to impart shearing stress to the test surface.
For tests of bare concrete, the surface should be prepared first with a diamond planing tool to produce a flat surface and to expose the coarse aggregate. Before bonding the ring, a special double -barrel coring bit is used to produce partial cores as illustrated below. The coring bit diameters match the inner and outer diameters of the ring.
After the adhesive has cured, a torque is applied to the ring until rupture occurs due to shearing stress. The torque is applied with a special torque housing that is anchored to the surface. The loading is accomplished with the pull machine used for the CAPO-TEST. The load from the pull machine is applied eccentrically to the torque housing, thus producing a torsional moment.
The peak force is recorded and is converted to a shear strength using the provided conversion relationship, as shown above (right).
Additional information can be found in the following reference:
Petersen, C.G. and Poulsen, E., “In-Situ Testing of Near-to-Surface Layer of Concrete and Epoxy-Bonded CFRP Strips,” US-Canada-Europe Workshop on Bridge Engineering, Zürich, Switzerland, 1997.
Variation
The coefficient of variation of replicate test results is about 10 % on concrete with a maximum aggregate size of 38 mm.
Testing Example
Testing with the TORQ-TEST on a bridge girder before application of CFRP strips
The TORQ-TEST Equipment and Ordering Numbers
TORQ-800 kit
Item | Order # |
---|---|
Torque housing with eccentric loading | TORQ-810 |
Torque discs, 6 pcs | TORQ-820 |
Steel brush | TORQ-830 |
GRA glue, box | B-11060 |
Set of anchoring tools, 8 mm | TORQ-850 |
Anchors, 8 mm, 20 pcs | TORQ-860 |
Emery cloth | TORQ-870 |
Rubber ball dust remover | TORQ-880 |
Hammer | TORQ-890 |
Manual | TORQ-900 |
Attaché case | TORQ-910 |
C-104 CAPO-TEST Pull Machine Kit
Item | Order # |
---|---|
Hydraulic pull machine with electronic gauge, 0-100 kN, 0.1 kN digital division |
L-11-1 |
AMIGAS printout software | L-13 |
Cable for printout | L-14 |
Oil refilling cup | L-24 |
Oil refilling bottle | L-25 |
Large screwdriver | C-149 |
Small screwdriver | C-157 |
Calibration table | TORQ-920 |
Manual | TORQ-930 |
Attaché case | TORQ-940 |
The twin drill bit for partial coring (Order # TORQ-950) is used with the CS-75 CORECASE.