TORQ-TEST

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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.
torQ_1 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

torQ_2 Testing with the TORQ-TEST on a bridge girder before application of CFRP strips

The TORQ-TEST Equipment and Ordering Numbers

TORQ-800 kit
torQ_3

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
torQ_4

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.

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