Capo Test on Hardened Concrete | CAPO Test | LOK Test

Capo Test on Hardened Concrete


A pullout test measures the force required to pull a specially shaped steel rod or disc out of the hardened concrete into which it has been cast.

Types of Pull Out Tests:

Depending upon the placement of disc/ring in the fresh concrete, pull out test can be divided into 2 types

  1. LOK test
  2. CAPO test (Cut and Pull out Test)

What Is the Capo Test?

Cut and Pull Out (CAPO) is an effective test method for determining RCC constructions’ in-situ compressive strength.

The results of the CAPO test are found to be within 8% of those obtained using traditional or conventional procedures.

A diamond tool, shaped like a dentist’s drill and larger at the tip than at the base, is used to recess the groove into the central hole.

The CAPO tests are used to assess the compressive strength of in-situ concrete in structures such as concrete roads, bridges, and buildings.

The CAPO test is performed in compliance with ASTM C900, BS-1881: Part 207, and EN-12504-3 requirements and is accredited by the Indian Road Congress (IRC).

Applications of Capo-Test

The finished construction is subjected to quality assurance testing.

If the strength of standard-cured specimens fails to satisfy acceptance criteria, verification of in-place strength is required.

Estimating the concrete strength of existing structures that have been damaged by fire is assessed.

Ascertain the strength of concrete for carrying out post-tensioning operations.
Determine the time of removal of forms and shores based on the actual in-situ strength of the structure.

Criteria for Fixing the Target Test Concrete Surface for Capo Test

Ensure that reinforcing bars are not within the failure region when choosing a location for a CAPO-TEST.

A planning tool is used to smooth the surface at the test site, and a diamond-studded core bit is used to drill an 18.4 mm hole perpendicular to the surface.

In the hole, a recess (slot) with a diameter of 25 mm and a depth of 25 mm is routed. A split ring is expanded in the recess and pulled out using a pulling machine reacting against a 55 mm diameter counter-pressure ring.

The concrete in the strut between the enlarged ring and the counter-pressure ring is in compression, as in the LOKTEST.

As a result, the ultimate pullout force F is proportional to compressive strength.

The basic premise of pull-out testing is that test equipment with a specified geometry will yield results that are closely related to concrete compressive strength.

The force required to pull a steel disc or ring embedded in fresh concrete against a circular counter pressure placed on the concrete surface concentric with the disc/ring yields this correlation.

The test continues until the conic frustum between the expanding ring and the counter pressure’s inner diameter is dislodged.

As a result, there is minimal surface damage that should be rectified for aesthetic reasons or to avoid long-term concerns.

General Instructions for CAPO TEST:

The placement of the test should not be chosen over the reinforcement mesh.
Drill machine should be axially & core to half depth during center hole coring, then remove it and continue drilling to full depth.

Axial planning should be done for the testing surface.

The recess was meticulously routed.

Flush with water during capo-Insert expansion to remove any remaining particles inside the hole.

Install the counter pressure and coupling, and ensure the coupling’s three little pins are facing towards the concrete.

To completely expand the Capo-Test hydraulic pull machine, it should be cranked anti-clockwise 39 times.

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