Original Cerchar abrasiveness index tester (OCAI 70) – ASTM D The OCAI accurately determines the rock abrasivity index (CAI) employed for the. ASTM D Standard Test Method for Laboratory Determination of Abrasiveness of Rock Using the CERCHAR Method Link. Two standards exist for this test method: the French. standard AFNOR NF P () and ASTM. D (). The test is widely.

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Pricing information and quote request on Geotechgate. The main difference between the two methods is in the duration of the test. Abraison can be defined as wearing or tearing away of particles and material from the solid surface. Reliable results depend on many factors; Practice D provides a means of evaluating some of those factors. The rock sample is placed in the equipment and firmly clamped using a rigid vice. It is the responsibility of the user of this standard to establish appropriate safety and health practices and determine the applicability of regulatory limitations prior to use.

Mechanical properties

It allows to determine an index called CERCHAR Abrasicity Index CAI for the rock’s abrasivity which can be used for evaluate the wear of excavation equipment atsm different application such as mining, tunnelling and drilling.

The Cerchar abrasiveness index.

Link to Active This link will always route to the current Active version of the standard. Work Item s – proposed revisions of this standard.

ASTM D7625 – 10

There are two equipment design to run the test:. D76225 abrasiveness testing for tunnelling. The device is rigid and 7d625 fixed to avoid any lateral movement. The test method consists of measuring the wear on e7625 tip of steel stylus with a cone shape and known Rockwell Hardness, caused by scratching against a freshly broken or saw cut rock surface for a prescribed 10 mm distance using one of the two test apparatus.


Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard.

The abrasivity of rock and soil is a factor of significant importance for excavation in tunnelling, underground construction, mining or quarrying. The CAI values obtained for both testing velocities 1 are estimated to be equal.

The dead load is then placed on the top of the pin and the pin is carefully lowered to the rock surface. Users of these practices are cautioned that compliance with Practice D does not in itself assure reliable results.

Cerchar Abrasivity test –

The testing principle is based on a steel pin with defined geometry and hardness that is scratches the surface of a rough rock sample over a distance of 10 mm under static load d762 70 N.

It should have a diamater of at least 6 mm and the length should be such at the visibile part of th epin is at least 15 mm. In heterogeneous rock types such as conglomerates, coarse grained granite or schistose rock, suitable fresh test surfaces are not achieved by mechanical breakage using a hammer.

Agencies that meet the criteria of Practice D are generally considered capable of competent and objective testing and sampling. There are two equipment design to run the test: The Cerchar- Abrasivity-Index CAI is then calculated from the measured diameter of the resulting wear flat on the pin: While, in the West design, the rock sample moves under a stationary pin. The test is then carried dd7625 by relative displacement of the pin on the rock surface across 10 mm at given time intervals.


The Cerchar- Abrasivity-Index CAI is then calculated from the measured diameter of the resulting wear flat on the pin:. Free quote for buying vane shear test equipment: Rock abrasiveness governs the performance of disc cutters, the rate of its replacement and therefore subsequent tunnel costs.

ASTM D | Testing Services | Cerchar Abrasivity Index (CAI)

However, there are situations where stylus with different Rockwell Hardness can be used Therefore, this test method includes discussions on stylus with different Rockwell Hardness. CAI is used to assess the abrasiveness of rock for mechanical excavation.

Both devices include the following main parts: After the test, th epin is carefully removed and the tip flat wear is measured. Abrasiveness expresses a behavioral characteristic of rock rather than a fundamental physical or mechanical property. Copyright – Geotechdata. Cerchar Abrasivity test equipment The testing principle is based on a steel pin with defined geometry and hardness that is scratches the surface of a rough rock sample over asstm distance of 10 mm under static load of 70 N.

CAI tests were originally carried out on natural broken surfaces.

No other asym of measurement are included in this standard. Advances in methods of underground excavation, in particular the use of the tunnel boring machine TBMnecessitates knowledge of rock abrasiveness. Can you edit this page?