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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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. Note 1—The quality of the result produced by these practices is dependent upon the competence of the personnel performing it and the suitability of the equipment and facilities used.

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

Work Item s – proposed revisions of this standard. Send us an email to editor geotechdata. CAI is used to assess the abrasiveness of rock for mechanical excavation. Agencies that meet the criteria of Practice D are generally considered capable of competent and objective testing and sampling.

The rock sample is placed in the equipment d765 firmly clamped using a rigid vice.

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Abraison can be defined as wearing f7625 tearing away of particles and material from the solid surface. Rock abrasiveness governs the performance of disc cutters, the rate of its replacement and therefore subsequent tunnel costs.

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.

Referenced Documents purchase separately The documents listed below are referenced within the subject standard but are not provided as part of the standard. No other units of measurement are included in this standard. After the test, th epin is carefully removed and the tip flat wear is measured.


The abrasivity of rock and soil is a awtm of significant importance for excavation in tunnelling, underground construction, mining or quarrying. Pricing information and quote request on Geotechgate.

Laboratory Tests on Rock – List of Tests – Tonon USA

The Cerchar- Abrasivity-Index CAI is then calculated from the measured diameter adtm the resulting wear flat on the pin: Abrasiveness expresses a behavioral characteristic of rock rather than a fundamental physical or mechanical property.

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 of 70 N. The Cerchar abrasiveness index. There are two equipment design to run the test: Free quote for buying vane shear test equipment: Advances in methods of underground excavation, in particular the use asym the tunnel boring machine TBMnecessitates knowledge of rock abrasiveness.

The Cerchar- Abrasivity-Index CAI is then calculated from the measured diameter of the resulting wear flat on s7625 pin:.

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 a distance of 10 mm under static load of 70 N.

It should have a diamater of at d6725 6 mm and the length should be such at the visibile part of th epin is at least 15 mm.

While, in the West design, the rock sample moves under a stationary pin. The device is rigid and also fixed to avoid any lateral movement. Both devices include the following main parts: The test is then carried out by relative displacement of the pin ast the rock surface across 10 mm at given time intervals. Rock abrasiveness testing for tunnelling.


Link to Active This link will always route to the current Active version of the standard. 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.

Can you edit this page? The test method consists of measuring the wear on the tip of steel stylus with a cone shape aastm known Rockwell Hardness, caused by scratching against astmm freshly broken or saw cut rock surface for a prescribed 10 mm distance using one of the two test apparatus.

Users of these practices are cautioned that compliance with Practice D does not in itself assure reliable results. The CAI values obtained for both testing velocities 1 are estimated to be equal. Copyright – Geotechdata.

CAI tests were originally carried out on natural broken surfaces. 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 in different application ast as mining, tunnelling and drilling.

CERCHAR abrasivity test

The main difference between the two methods is in the duration of the test. The dead load is then placed on the top of the pin and the pin is carefully lowered to the rock surface.

There are two equipment design to run the test:. Reliable results depend on many factors; Practice Sstm provides a means of evaluating some of those factors.