1
 Open Access. © 2020 Janc B., Jovičić V., Vukelić Ž., published by Sciendo.  This work is licensed under the Creative 
Commons Attribution-NonCommercial-NoDerivatives 4.0 License. 
Received: Aug 17, 2020 
Accepted: Sep 07, 2020 
DOI: 10.2478/rmzmag-2020-0012
Review paper
Abstract
In geotechnology and mining, tools and equipment in-
teract with aggressive geological material, causing the 
wear of these components. For this reason, it is import-
ant to determine the rate of abrasivity of individual 
geological materials, depending on the type of inter-
action with the tool. Various abrasivity tests have been 
developed in laboratories. Some of them are general, 
while others are special. What they all have in common 
is that they attempt to determine the abrasivity of rocks 
or soils in relation to the wear of the test specimens. 
This article gives an overview of the laboratory test 
methods for assessing the abrasivity of geological ma-
terials, which are useful in the field of geotechnology 
and mining engineering. General and special abrasivi-
ty tests are presented in detail. The aim of the article 
is to present existing laboratory tests to assess the 
abrasivity of rocks and soils, based on which further 
investigations of wear can be considered as part of a 
comprehensive approach to this tribological problem. 
Understanding of the wear mechanisms is the basis for 
the development of wear-resistant tools and models for 
predicting the tool life.
Key words: laboratory testing, abrasivity, wear, geote-
chnology, mining.
Laboratory Test Methods for Assessing 
the Abrasivity of Rocks and Soils in Geotechnology 
and Mining Applications
Laboratorijske preiskave abrazivnosti kamnin in zemljin na 
področju geotehnologije in rudarstva
B. Janc*, V. Jovičić, Ž. Vukelić
University of Ljubljana, Faculty of Natural Sciences and Engineering, Department of Geotechnology, Mining and Environment, 
Aškerčeva 12, Ljubljana, Slovenia
* blaz.janc@ntf.uni-lj.si
Povzetek
V geotehnologiji in rudarstvu so orodja in oprema v in-
terakciji z agresivnim geološkim materialom, ki povzro-
ča obrabo omenjenih komponent. Zaradi tega obstaja 
težnja po določevanju stopnje abrazivnosti posameznih 
geoloških materialov glede na vrsto interakcije z orod-
jem. V laboratorijih so bile razvite različne preiskave 
abrazivnosti. Ene od njih so splošne, druge namenske. 
Vsem pa je skupno to, da skušajo določiti abrazivnost 
kamnin ali zemljin glede na obrabo preizkušanca. 
V članku je predstavljen pregled laboratorijskih prei-
skav abrazivnosti geoloških materialov, ki so uporabne 
na področju geotehnologije in rudarstva. Splošne in 
namenske preiskave abrazivnosti so podrobno pred-
stavljene. Namen članka je predstaviti obstoječe labo-
ratorijske preiskave abrazivnosti kamnin in zemljin, na 
podlagi katerih je mogoče nadaljnje preiskovanje obra-
be kot del celovitega pristopa pri tem tribološkem pro-
blemu. Razumevanje mehanizmov obrabe je podlaga za 
razvijanje orodij, odpornih proti obrabi ter modelov za 
napovedovanje njihove življenjske dobe.
Ključne besede: laboratorijsko preiskovanje, abraziv-
nost, obraba, geotehnologija, rudarstvo

Janc B., Jovičić V., Vukelić Ž. RMZ – M&G | 2020 | Vol. 67 | pp. 01–15
2
Introduction
Geotechnology as an engineering discipline is 
confronted with many cases in which tools and 
equipment in dynamic contact with geologi-
cal material get worn out. They are exposed to 
high compression, shear and impact loads. The 
result of these loads is material damage to the 
tools and equipment used in the technological 
process, which gradually reduces their func-
tionality.
The areas of geotechnology where the wear 
of tools and equipment are most pronounced 
(Figure 1) can be divided into the following 
four main groups:
1) Tunnelling
2) Drilling
3) Mining 
4) Mineral processing
The first group includes the tunnelling sector, 
which deals with the construction of road and 
rail tunnels, as well as tunnels for water trans-
port and sewerage. Tunnelling can be carried 
out conventionally by drilling and blasting 
or mechanised with tunnel boring machines 
(TBMs) or excavation machines (roadheaders). 
Both the excavation methods lead to tool wear. 
In the conventional method, the drill bits are 
worn out when drilling boreholes, whereas in 
the mechanised method the disc cutters on the 
TBM or the teeth on the head of the excavation 
machine (roadheader) are worn out.
The second group includes the drilling sector, 
which deals with the drilling of production, ex-
ploratory or technical boreholes. Production 
wells are intended for the production of min-
erals and energy, such as oil, gas and geother-
mal energy. Exploratory boreholes are used for 
geological–geomechanical investigations. Tech-
nical boreholes are used for rock blasting and 
anchoring geotechnical constructions. All these 
operations, during which percussion or rotary 
drilling is performed, cause wear on the teeth 
or inserts of the drill bits, which are the main 
tool for drilling boreholes.
The third group includes the mining sector, 
which deals with the surface or underground 
extraction of mineral resources, including 
metals, non-metals and energy resources. In 
the mining sector, wear occurs mainly in two 
areas: the extraction and transport sectors. In 
the extraction sector, tools are worn on mech-
anised mining excavation machines such as the 
longwall shearer, continuous miner and bucket 
wheel excavator. In the transport sector, wear 
occurs on transport machines and equipment.
The fourth group includes the mineral pro-
cessing sector, which deals with the processing 
and preparation of mineral resources for use in 
various industrial processes. Most pronounced 
is the wear of equipment used to increase the 
specific surface area of the mineral resources. 
This includes crushing and grinding machines. 
Wear occurs on parts of the equipment that are 
in contact with the mineral. These are usually 
plates in various crushers and grinding media 
in mills.
In all the four groups described above, it is pos-
sible to find the occurrence of material wear 
that forms a tool or equipment that is in dynam-
ic contact with geological material. In most cas-
es, the materials of the tools and equipment are 
steels which, due to their wide availability and 
economic acceptance, currently have the most 
suitable wear resistance.
Abrasivity and Tribological System
Abrasivity plays an important role in the pro-
cess of wear. It is a property that reflects the 
ability of a rock (geological material) to cause 
wear on materials [1]. The tribological system 
combines all components necessary for the 
wear process. These components are as fol-
lows:
1) Geological material
2) Tool material
3) Surrounding medium
4) Type of load (dynamic interaction)
A change in any of the above components also 
changes the mode and rate of wear. Figure 2 
schematically shows a tribological system with 
all four components.
There are several methods for estimating the 
abrasivity of rocks and soils. In general, three 
categories can be distinguished [2]:
1) Indirect methods – assessment of abrasivi-
ty by a combination of different geomechanical 
properties such as hardness, uniaxial compres-
sive strength, tensile strength and other funda-
mental properties.

Laboratory Test Methods for Assessing the Abrasivity of Rocks and Soils
3
Figure 1: Wear of tools in geotechnology and mining engineering. The most typical devices for each field are shown 
 (adapted from [3–16]).

Janc B., Jovičić V., Vukelić Ž. RMZ – M&G | 2020 | Vol. 67 | pp. 01–15
4
2) Direct methods – assessment of abrasivity by 
laboratory test methods where there is relative 
movement between the geological sample and 
the wear tool in contact under the influence of 
controlled standard conditions.
3) Holistic methods – assessment of abrasivity 
by a combination of the fundamental geome-
chanical properties of the geological material 
and other parameters of the process and envi-
ronment in which the wear occurs.
Indirect methods for assessing abrasivity have 
the advantage of using data that are already 
available or are relatively easy to obtain. How-
ever, they do not take into account the process 
variables for certain types of wear. Therefore, 
they are usually not used individually but in 
combination with direct or holistic methods.
The holistic methods for assessing abrasivity 
are very much related to certain equipment and 
processes and, therefore, have less value for 
other applications.
The direct methods for assessing abrasivity 
use the standard conditions to determine the 
abrasivity for a specific type of wear, either low 
or high stress or impact abrasion. The tests in-
vestigate the effects of relative movements be-
tween the geological sample and a wear tool in 
contact [2].
Laboratory Test Methods for Assessing 
the Abrasivity of Geological Material
Researchers have developed various laborato-
ry devices to test the abrasivity of individual 
rocks and soils directly in the laboratory. The 
test methods differ depending on the design of 
the device or apparatus, the duration of the test, 
the method of causing wear, the shape and size 
of the abrasive material and the wear tool, and 
the purpose of the test. Some abrasivity tests 
are general and standardised to some extent. 
However, most of the tests are special and were 
intentionally developed for certain technolog-
ical processes described in the introductory 
part of this article. It is worth noting that by far 
the largest number of abrasivity tests have been 
developed for mechanised tunnelling.
A general test method for assessing the abrasiv-
ity of geological material includes the CERCHAR 
abrasivity test for rocks and the LCPC abrasivity 
test for soils or grain materials. Both tests have 
been developed in France and are standardised.
Special test methods for assessing the abrasiv-
ity of geological material are those developed 
for a specific application, such as tunnelling, 
drilling and mineral processing. The group of 
tests for tunnelling includes NTNU/SINTEF (AV , 
AVS and SAT
TM
) and RIAT (rolling indentation 
abrasion test) abrasivity tests, which were de-
veloped for the estimation of tool wear in mech-
anised tunnelling. These abrasivity tests are not 
yet standardised. Miller abrasive test is used to 
determine the abrasivity of slurries and is stan-
dardised (ASTM G75 standard). The Gouging 
abrasion test can be used to estimate the wear 
of machine parts during crushing and grinding 
processes. The test is not standardised. It is also 
worth mentioning some other abrasivity tests 
that fall within the field of road construction. 
These are the (standardised) Los Angeles abra-
sion test, the Nordic ball mill test and the Dorry 
abrasion test, which all test the wear resistance 
of road aggregates.
CERCHAR Abrasivity Test
The CERCHAR abrasivity test was originally 
developed by a French laboratory (Laboratoire 
du Center d’Etudes et Recherches des Charbon-
nages de France) for mechanised coal mining. 
Figure 2: Tribological system (schematic).

Laboratory Test Methods for Assessing the Abrasivity of Rocks and Soils
5
This method is described by two standards, the 
French standard AFNOR NF P 94-430-1 and the 
International standard ASTM D7625-10 [17].
Apparatus
There are two types of testing apparatus. The 
first is the original design as developed at the 
CERCHAR centre and the second is a modified 
design as reported by West [17].
In the CERCHAR apparatus (Figure 3), the load-
ed stylus moves across the surface of a station-
ary rock sample. In the case of the West design 
(Figure 4), however, the rock sample moves un-
der the loaded stationary stylus. Different im-
plementations of the apparatus design lead to a 
test duration [17].
Both apparatus have a rigid vice for firmly 
clamping the rock sample. Sufficient rigidity of 
the apparatus ensures that there is no lateral 
movement during the test. The stylus is loaded 
with a weight of 70 N [17].
Stylus
The stylus is made of standard chrome–vana-
dium cold-work tool steel and is hardened to 
Rockwell hardness HRC 55 ± 1. The stylus di-
ameter should be at least 6 mm. The length of 
the stylus should be such that the visible part 
of the stylus between the pin chuck and the sur-
face of the rock sample is at least 15 mm. The 
pin of the stylus (Figure 5) has a conical shape 
with an angle of 90°. The worn pin should be 
resharpened and examined under a microscope 
before being used for further testing [17].
Test Sample
The rock sample can be circular or irregularly 
shaped. A test on freshly broken rock surface 
is recommended. The rough surface can be 
obtained by a Brazilian tensile test (Figure 6) 
on the rock disc or by firm hammer blows on 
a rock core or rock sample. Alternatively, the 
sample can be prepared with a water-cooled 
diamond saw blade. The surface to be tested 
should be cleared of debris or loose grains of 
rock. The size of the rock surface should be suf-
Figure 3: CERCHAR-type testing apparatus (adapted 
from [17]).
Figure 4: West-type testing apparatus (adapted from [17]).
Figure 5: Steel pin. (a) Before the test. (b) After the test (d is the 
wear flat) (adapted from [18]).
Figure 6: The two halves of the sample disc with test scratches 
(1–5) after Brazilian tensile test. (a) Rough surface. (b) Smooth 
surface (adapted from [20]).

Janc B., Jovičić V., Vukelić Ž. RMZ – M&G | 2020 | Vol. 67 | pp. 01–15
6
ficient to allow five test scratches at a minimum 
distance of 5 mm and 5 mm from the edge of the 
rock surface [17].
Test Procedure
A microscopic inspection of the stylus should 
be performed before the test. The rock sample 
should be firmly clamped in the vice with the 
rock surface as horizontal as possible. The sty-
lus should be carefully lowered onto the rock 
surface. The length of a test scratch in the rock 
sample must be exactly 10 mm. Depending on 
the apparatus design used, the test duration 
is 1 (CERCHAR version) or 10 s (West version). 
The stylus pin must be in constant contact with 
the rock surface during the test [17]. The main 
parameters of the CERCHAR abrasivity test are 
summarised in Table 1.
Table 1: Main parameters of the CERCHAR abrasivity test.
Parameters Value
Load (N) 70
Stylus hardness 
(HRC)
55 ± 1
Test scratch 
length (mm)
10
Sample material Rock (freshly broken surface)
CERCHAR WEST
Test duration 
(s)
1 10
Test result
CERCHAR abrasivity index 
(CAI)
At least five test repetitions must be carried out 
on the rock surface, each time with a new or re-
sharpened pin [17].
Stylus Wear Measurement
The measurement of the length or diameter of 
the pin wear (d) is carried out with optical and 
digital methods (microscope). The measure-
ment of the pin can be performed in the side or 
top view. However, it is recommended to mea-
sure in the side view [19]. Figure 7 shows the 
possible measurements of pin wear . When mea-
suring in the top view, the mean value between 
d
1
 and d
2
 is taken for d.
Calculation of CERCHAR Abrasivity Index
For each measurement of pin wear (d), the CER-
CHAR abrasivity index (CAI) is calculated as
CAI = d × 10 (1)
where d is the length of the wear pin surface 
measured with an accuracy of 0.01 mm [17].
The dimensionless CAI value is given as the 
arithmetic mean of five or more test repetitions 
together with the standard deviation [17].
Classification System
The system for classifying abrasivity after ISRM 
[17] is given in Table 2. This system differs 
slightly from that proposed by the CERCHAR 
centre.
Table 2: Classification of the CERCHAR abrasivity index (CAI) 
[17].
Mean value 
of CAI
Classification/abrasivity 
description
0.1–0.4 Extremely low
0.5–0.9 Very low
1.0–1.9 Low
2.0–2.9 Medium
3.0–3.9 High
4.0–4.9 Very high
≥5 Extremely high
Figure 7: Measurements of pin wear. (a) Side view (d is the 
distance between the edges of the worn surface). (b) Top view 
(d
1
 and d
2
 are diameters of the worn pin, measured from two 
orthogonal directions) (adapted from [17]).

Laboratory Test Methods for Assessing the Abrasivity of Rocks and Soils
7
LCPC Abrasivity Test
The LCPC abrasivity test was developed in the 
1980s by a French laboratory (Laboratoire Cen-
tral des Ponts et Chaussées) to test soil abrasiv-
ity. The method is described in French Standard 
P18-579 [21].
Test Device
The main components of the test device for 
determining abrasivity are the frame, the mo-
tor, the funnel tube, the metal impeller and the 
sample container. The device is shown sche-
matically in Figure 8. The 750 W motor ensures 
the rotation of the axle. A metal impeller is at-
tached to the end of the axle and is immersed 
in a sample container, which is cylindrical in 
shape with a diameter of 93 mm and a height 
of 100 mm. The metal impeller (test speci-
men) has a rectangular shape with dimensions 
50 mm x 25 mm x 5 mm. The impeller is made 
of standardised steel with a Rockwell hardness 
of HRB 60–75. The steel impeller must be re-
placed after each test [21].
Test Sample
The LCPC testing device is designed to investi-
gate the abrasivity of granular materials with 
a grain size of 4–6.3 mm. According to French 
Standard P18-579 a sample of 500 g ± 2 g of a 
dry material with a grain size of 4–6.3 mm is re-
quired. The required grain size of the sample is 
achieved by sieving. Fractions below 4 mm and 
above 6.3 mm must not be used in the test [21].
Test Procedure
The sample container is filled with the required 
granular material through the funnel tube of 
the testing device. The rectangular metal im-
peller rotates for 5 min in a sample container 
at 4,500 rpm. To determine the abrasivity of the 
sample material, it is necessary to determine 
the mass of the metal impeller before and after 
the test. The mass loss of a metal impeller is a 
measure of the abrasivity of the sample. With 
the loss of mass, the metal plate also deforms. 
The more abrasive the material sample is the 
greater the deformation and mass loss of the 
impeller [21]. Figure 9 shows schematically the 
metal impeller before and after the LCPC test. 
The main parameters of the LCPC abrasivity 
test are summarised in Table 3.
Table 3: Main parameters of the LCPC abrasivity test.
Parameters Value
Rotational speed 
(min
−1
)
4,500
Sample  
material
Soil/granular material
Grain size of the 
sample (mm)
4–6.3
Sample  
mass (g)
500 ± 2
Test  
duration (min)
5
Test result
LCPC  
abrasivity  
coefficient  
(LAC)
LCPC  
breakability  
coefficient  
(LBC)
Figure 8: LCPC abrasivity testing device with main 
components (adapted from [18]).

Janc B., Jovičić V., Vukelić Ž. RMZ – M&G | 2020 | Vol. 67 | pp. 01–15
8
Calculation of LCPC Abrasivity Coefficient
The LCPC abrasivity coefficient (LAC) is calcu-
lated as the coefficient of mass loss of the metal 
impeller and the sample mass [21] as
𝐿𝐿𝐿𝐿𝐿𝐿 =
𝑚𝑚 0
− 𝑚𝑚 𝑀𝑀   (2)
where LAC is the LCPC abrasivity coefficient 
(g/t), m
0
 is the mass of the steel impeller before 
the LCPC test (g), m is the mass of the steel im-
peller after the LCPC test (g) and M is the mass 
of the sample material (=0.0005 t).
The LAC for natural rocks and soils varies be-
tween 0 and 2,000 g/t. The value range can 
be divided into five classes. As there is a close 
linear correlation (Figure 10) between the LAC 
and the CAI index, the CAI abrasivity classifica-
tion can be used [21].
Classification System
The abrasivity classification system in relation 
to the CAI is given in Table 4 [21].
Table 4: Classification of LCPC abrasivity coefficient (LAC) in 
relation to the CERCHAR abrasivity index (CAI) [21].
LAC (g/t)
CAI 
(0.1 mm)
Abrasivity term
0–50 0–0.3 Not abrasive
50–100 0.3–0.5 Not very abrasive
100–250 0.5–1.0 Slightly abrasive
250–500 1.0–2.0 (Medium) abrasive
500–1,250 2.0–4.0 Very abrasive
1,250–2,000 4.0–6.0
Extremely 
abrasive
NTNU/SINTEF Abrasivity Tests
NTNU/SINTEF abrasivity tests have been de-
veloped at the Norwegian University of Science 
and Technology in Trondheim (NTNU-Norges 
teknish-naturvitenskapelige universitet) in co-
operation with the research organisation SIN-
TEF (Stiftelsen for industriell og teknisk forsk-
ning).
The AV abrasivity test was developed in the 
1960s to evaluate the wear of drill bits. It pro-
vides a measure of rock abrasion or the ability 
to induce wear on a tungsten carbide speci-
men [22].
The AVS abrasivity test was developed between 
1980 and 1983 based on the AV test. The pur-
pose of the test is to evaluate the tool life of 
mechanised rock TBM tunnelling. Compared to 
the AV test, the AVS test differs in the specimen 
material and the duration of the test. The AVS 
is a measure of rock abrasion or the ability to 
induce wear on cutter ring steel [22].
Soil abrasion test (SAT
TM
) was introduced in 
2005 to evaluate the tool life of mechanised 
TBM tunnelling in soft ground and in soil. The 
test is a further development of the NTNU/SIN-
TEF abrasion tests for rock. The test device for 
the soil abrasion test is identical to the device 
for AV and AVS abrasivity tests. The difference 
is in the sample material [23].
The abrasivity tests are quite similar, except 
that the AV test measures the wear of a tung-
sten carbide specimen and the AVS and SAT
TM
 
tests measure the wear of a specimen made of 
TBM cutter ring steel [22, 23].
Figure 9: Schematic representation of metal impeller before 
and after the LCPC test: 1 new impeller, 2 not abrasive, 3 
abrasive/very abrasive, 4 very abrasive and 5 extremely 
abrasive (adapted from [21]).
Figure 10: Correlation between LAC and CAI [21].

Laboratory Test Methods for Assessing the Abrasivity of Rocks and Soils
9
Device
The device is identical for all three abrasivity 
tests. In the individual tests, the grain size of 
the rock or soil sample and the material of the 
test specimen are different.
The device, which is shown schematically in 
Figure 11, consists of a drive, a rotating steel 
disc, a test specimen, a weight, a sample mate-
rial feeder and a suction device.
Test Specimen
The material of the specimen in the AV test is 
tungsten carbide. The specimen in the AVS and 
SAT
TM
 tests is steel taken from the TBM cut-
ter ring. The test specimen is cuboidal with a 
rounded surface in shape. The length of the test 
specimen for the AV and AVS tests is 30 mm, the 
width is 10 mm and the radius is 15 mm. The 
test specimen for the AV and AVS tests is shown 
in Figure 12.
The length of the test specimen for the SAT
TM
 
test is 30 mm, the width 20 mm and the radius 
15 mm. The test specimen for the SAT
TM
 test is 
shown in Figure 13. During the rotation of the 
steel plate the rock or soil sample passes under 
the rounded part of the stationary test speci-
men.
Sample Material
Crushed rock powder with a grain size of less 
than 1 mm is used for the AV and the AVS 
tests. Therefore the sample material has to be 
crushed and/or ground and sieved before the 
test.
For the SAT
TM
 test, a dry and gently crushed soil 
sample with a grain size of less than 4 mm is 
used. The SAT
TM
 test is applicable for the inves-
tigation of clay, silt and sand fractions [23].
Test Procedure
Abrasivity tests AV, AVS and SAT
TM
 represent 
the time-dependent abrasion of tungsten car-
bide (AV) or TBM cutter ring steel (AV, SAT
TM
), 
caused by rock powder or soil grains. The same 
test device is used for all the three tests.
A circular steel disc with a circumference of 
1,000 mm (318.3 mm diameter) is set horizon-
tally and rotates around its axis at a speed of 
20 rpm. A rock or soil sample falls via the feed-
er onto the upper outer part of the steel disc 
and forms a material belt. The mass flow rate of 
the sample material is approximately 80 g/min. 
In front of the feeder (in the direction of rota-
tion) a test specimen is mounted and loaded 
with a normal force of 100 N. The test speci-
men is firmly clamped and is stationary during 
the test. The contact between the test speci-
men and the sample material causes abrasive 
wear of the test specimen. A suction device is 
installed behind the feeder (in the direction of 
rotation) to remove the sample material from 
Figure 11: NTNU/SINTEF abrasivity device (adapted from [22]).
Figure 12: Test specimen for rock abrasivity test AV and AVS 
(adapted from [23]).
Figure 13: Test specimen for soil abrasivity test SAT
TM
 
(adapted from [23]).

Janc B., Jovičić V., Vukelić Ž. RMZ – M&G | 2020 | Vol. 67 | pp. 01–15
10
the steel disc. This allows the test specimen to 
remain in contact with new material during 
the entire test. The length of the path that the 
test specimen travels on the sample material is 
100 m for the AV test and 20 m for the AVS and 
SAT
TM
 test [22, 23].
The duration of the AV test is 5 min or 100 disc 
rotations, that is, 100 m.
The duration of the AVS and SAT
TM
 test is 1 min 
or 20 disc rotations, that is, 20 m.
The tests AV, AVS and SAT
TM
 are normally car-
ried out on 2–4 test specimens. The deviation 
is very small and should not exceed 5 mg of 
weight loss if the test is performed correctly. 
The reported AV, AVS and SAT
TM
 values are the 
main values of 2–4 parallel tests [22]. The main 
parameters of the NTNU/SINTEF abrasivity 
tests are listed in Table 5.
Table 5: Main parameters of the NTNU/SINTEF abrasivity 
tests.
Parameters Value
Load (N) 100
Rotational 
speed (min
−1
)
20
Material mass 
flow (g/min)
80
AV AVS SAT
TM
Test duration 
(min)
5 1 1
Sample 
material
Crushed 
rock 
powder
Crushed 
rock 
powder
soil
Grain size of 
the sample 
(mm)
<1 <1 <4
Test specimen 
material
Tungsten 
carbide
Cutter 
ring steel
Cutter 
ring 
steel
Test result AV value AVS value
SAT
TM
 
value
A V , A VS and SAT
TM
 values
To determine the abrasivity, it is necessary to 
measure the mass of the test specimen before 
and after the test. The loss of mass of the test 
specimen is a measure of the abrasivity of the 
rock or soil sample.
Classification System
The classification given in Table 6 is based 
on the distribution of the recorded results 
of the 2,621 samples used to determine AV, 
1,590 samples tested to determine AVS and 
254 abrasivity measurements on soil samples 
for the determination of SAT
TM
. The reason for 
proposing only three classification categories 
for SAT
TM
 is the relatively small amount of data 
compared to AV and AVS measurements [23].
Table 6: Classification of rock and soil abrasion on tungsten 
carbide (AV) and cutter steel (AVS, SAT
TM
) test specimen [22].
Abrasion AV (mg) AVS (mg) SAT
TM
 (mg)
Extremely 
high
≥58.0 ≥44.0
Very high 42.0–57.9 36.0–44.0
High 28.0–41.9 26.0–35.9 ≥22.0
Medium 11.0–27.9 13.0–25.9 7.0–22.0
Low 4.0–10.9 4.0–12.9 ≤7.0
Very low 1.1–3.9 1.1–3.9
Extremely 
low
≤1.0 ≤1.0
RIAT Abrasivity Test
The RIAT was developed at the Norwegian Uni-
versity of Science and T echnology in Trondheim 
(NTNU-Norges teknish-naturvitenskapelige 
universitet). The aim of the test is to imitate the 
wear behaviour of TBM cutter discs in mech-
anised tunnelling.
The rock and soil abrasivity tests described 
previously (CERCHAR, LCPC, NTNU) use sliding 
and impact contacts to induce wear. In contrast 
to the tests described above, the RIAT is based 
on a rolling contact that is more realistic for 
assessing disc cutter wear. Another difference 
between some abrasivity tests and the RIAT is 
that these tests use crushed rock samples in-
stead of intact samples [24].
Device
The RIAT device, schematically shown in Fig-
ure 14, consists of two interchangeable minia-

Laboratory Test Methods for Assessing the Abrasivity of Rocks and Soils
11
ture rolling discs that roll over and penetrate 
the surface of an intact rock sample. Rotation, 
torque and vertical thrust are provided by a 
drive unit [24].
The rolling diameter or the distance between 
two miniature discs is 60 mm. The diameter of 
the miniature rolling disc is 30 mm and the tip 
width is 4 mm [24].
Test Sample
The test sample is intact rock that can have any 
shape. It is recommended that the surface of 
the rock sample is smooth and horizontal. Usu-
ally a circular rock core is used for the test. In 
such a case the minimum diameter of the rock 
sample is 100 mm [24].
Miniature Rolling Discs
Miniature rolling discs are made of hot work 
tool steel AISI type H13, which is normally used 
for the actual TBM cutter rings. The miniature 
discs have a constant tip width of 4 mm. The 
diameter of the discs is 30 mm. The Rockwell 
hardness of the steel is HRC 50 ± 1 [24].
Test Procedure
The test is carried out in such a way that two 
miniature discs roll over a rock sample under 
the influence of the normal thrust of 1,250 N 
at a speed of 40 rpm and a center distance 
of 60 mm. The test parameters were deter-
mined in relation to real cutter parameters in 
mechanised TBM tunnelling in hard rock. The 
test duration is 30 min. Rock dust and debris 
formed during the test should be removed from 
the surface of the rock to be tested to ensure 
that the miniature rolling disc is in constant 
contact with the rock sample. A combination 
of compressed air and suction is used for this 
purpose [24]. The main parameters of the RIAT 
are listed in Table 7.
Table 7: Main parameters of the RIAT [24].
Parameters Value
Thrust (N) 1,250
Rolling velocity 
(min
−1
)
40
Test duration (min) 30
Disc hardness 
(HRC)
50 ± 1
Sample material Rock (smooth surface)
Test result
RIAT abrasivity index 
(RIAT
a
)
RIAT indentation index 
(RIAT
i
)
Determination of the RIAT Abrasivity Index 
and the RIAT Indentation Index
The result of RIAT is the RIAT abrasivity index 
(RIAT
a
) and the RIAT indentation index (RIAT
i
).
RIAT
a
 is defined as the mass loss of the minia-
ture rolling disc, measured in milligrams after 
the test. A representative mean value is deter-
mined by at least three tests [24].
RIAT
i
 is defined as the mean value of 10 evenly 
distributed measurements of the penetration 
depth of the miniature rolling disc into the rock 
Figure 14: RIAT device (adapted from [24]).

Janc B., Jovičić V., Vukelić Ž. RMZ – M&G | 2020 | Vol. 67 | pp. 01–15
12
surface in 1/100 mm. The RIAT
i
 value is an in-
dication of the penetration resistance of the 
rock or the hardness of the rock surface [24].
In the study reported by Macias et al. [24], eight 
types of rocks were selected for the RIAT. At 
least three parallel tests were carried out for 
each rock type, so that a total of 29 were per-
formed. The lowest and highest RIAT
a
 of the 
test performed is 3 for limestone and 104 for 
quartzite. The lowest and highest RIAT
i
 of the 
test carried out is 5 for quartzite and 380 for 
limestone.
As the study shows, RIAT
a
 and RIAT
i
 are in-
versely correlated. A higher RIAT
a
 means a low-
er RIAT
i
 [24].
Due to a small number of tests carried out, the 
classification for the RIAT has not yet been de-
termined.
Gouging Abrasion Test
The gouging abrasion test was developed to 
assess rock abrasivity in environments where 
high stress loads are expected at high speeds 
and at different angles of incidence. These con-
ditions can be achieved in many mineral pro-
cessing and mining equipment. Abrasion under 
such conditions causes considerable wear of 
the tool material [2].
Apparatus
A gouging abrasion test simulates very high 
stress abrasion under high-energy impact con-
ditions [2].
The rock sample with a rectangular shape and 
flat surface is clamped in the sample holder. 
A steel pin with a 90° angle is attached to the 
end of the pendulum arm. The length of the 
pendulum arm is such that the steel pin forci-
bly touches the surface of the rock sample as it 
swings past, creating a scratch along the entire 
length of the rock sample [2].
The apparatus is shown schematically in Fig-
ure 15. The rock sample is held securely in the 
sample holder, which can be moved vertical-
ly and horizontally by means of the transfer 
screw or spring mechanism. The wear tool is 
rigidly positioned in the tool holder of the pen-
dulum arm, which is released from its working 
position. The steel pin scratches over the rock 
surface as it moves. The pendulum has 300 J 
available impact energy. The impact speed is 
5.2 m/s [2].
Test Sample
The rock sample has a rectangular shape with 
a length of 80 ± 0.5 mm. Due to irregularities 
in the samples, the width can vary and take on 
values between 25 and 50 mm. The thickness 
of the sample is between 10 and 16 mm. The 
examined surface of the rock sample is flat and 
smooth, as is the case with a diamond saw cut. 
This eliminates the influence of the different 
surface roughness of the rock sample on the 
test results [2].
Wear Tool
According to Golovanevskiy and Bearman [2], 
a wear tool of Rockwell hardness HRC 40–42 
is recommended for the gouging abrasion test. 
The wear tool is made of steel AS 1444/4340-Y. 
The tool is 25 mm long with a diameter of 
9.375 ± 0.25 mm. The tool pin has a 90° angle.
Test Procedure
The prepared rock sample is placed in the 
sample holder. It is necessary to ensure the 
horizontal surface of the sample to be exam-
ined. The apparatus is equipped with a screw 
device for fine adjustment of the sample height 
and a spring system for rapid horizontal move-
ment [2].
The wear tool is carefully inserted into the 
wear tool holder of the pendulum arm. When 
the pendulum arm is fully vertical, the pin of 
the wear tool is directed vertically into the test 
surface of the rock sample in the holder. At this 
point, there are a few millimetres of clearance 
Figure 15: Gouging abrasion test apparatus. (a) Front view. 
(b) Side view (adapted from [2]).

Laboratory Test Methods for Assessing the Abrasivity of Rocks and Soils
13
between the pin of the wear tool and the sur-
face of the rock sample [2].
The sample holder is then lifted together with 
the sample via a screw assembly to achieve a 
slight contact between the surface of the rock 
sample and the wear tool pin [2].
The pendulum arm is lifted to its initial posi-
tion. The sample holder with the rock sample 
is then raised by 1.0 mm. The accuracy is mea-
sured with a micrometre. This allows a 1.0-mm 
deep wear tool cut in the rock sample. The 
wear tool is allowed to make a 78-mm long arc-
shaped cut on the surface of the rock sample, as 
shown in Figure 16 [2].
The pendulum arm is released. The pin of a 
wear tool produces a cut or scratch when it 
moves over a rock surface. The pendulum arm 
continues to move to the highest point of the 
path even as it passes the rock sample. When 
the pin of the wear tool is no longer in contact 
with the rock surface after the first swing, the 
sample holder moves quickly in a horizontal 
direction perpendicular to the plane of the 
pendulum motion via the spring mechanism. 
Due to this displacement of the rock sample, 
the wear tool and the rock surface no longer 
come into contact when the arm is moved back. 
The sample after several tests is schematical-
ly shown in Figure 17. When the pendulum 
stops, the wear tool is removed from the holder 
and the pin wear is measured. The rock sam-
ple holder is returned to its original working 
position and is moved about 5 mm to provide 
a fresh surface in the rock sample for further 
testing. The described procedure is valid for a 
single test run. For each further test run, a wear 
tool with an unused pin is inserted into the 
wear tool holder of the pendulum arm and the 
procedure described above is repeated [2]. The 
main parameters of the gouging abrasion test 
are listed in Table 8.
Table 8: Main parameters of the gouging abrasion test.
Parameters Value
Impact energy (J) 300
Wear tool hardness 
(HRC)
40–42
Test scratch length 
(mm)
78
Sample material Rock (smooth surface)
Test result
Gouging abrasion index 
(Gi)
Gouging Abrasion Index
The gouging abrasion index (Gi) is determined 
in the same way as the CAI, that is, the average 
distance of pin wear in millimetres multiplied 
by a factor of 10 [2].
For the representative value of the Gi, sever-
al tests should be carried out on a single rock 
sample. In practice, it is advisable to perform 
at least three test runs on a single rock sample, 
using a new wear tool and a fresh wear surface 
of the rock sample. This can be done with three 
wear tools and a 25–30-mm wide rock sam-
ple [2].
Conclusion
The wear of tools and equipment during tech-
nological processes in geotechnology and min-
ing is associated with high economic costs. On 
the one hand, there are the material costs as-
sociated with the replacement of worn tools 
or equipment, and on the other hand, there 
are the costs of downtime of the work process. 
The abrasivity is directly related to tool wear. 
Knowledge of the tribological system and wear 
mechanisms helps us to understand this com-
Figure 16: Wear contact between tool and rock sample 
(adapted from [2]).
Figure 17: Rock sample after testing (schematic). Numbers 
1–6 represent individual scratches from the test (adapted 
from [2]).

Janc B., Jovičić V., Vukelić Ž. RMZ – M&G | 2020 | Vol. 67 | pp. 01–15
14
plex problem. However, once the basics are 
known and the problem is understood, the 
next step can be taken, that is, the attempt to 
prevent it at least partially and the possibility 
to model or predict tool wear. It is not possi-
ble to prevent the abrasive wear of geotech-
nology and mining application tools in such an 
aggressive environment as the geological one. 
However, with the knowledge of the problem 
it is possible to develop materials that build 
tools. Every small step to improve the wear re-
sistance of a material is very valuable. The four 
main components of the tribological system 
are the geological material, surrounding medi-
um, tools and load type. It should be considered 
that the first two components mentioned above 
cannot be modified. However, the tool (and the 
material it is made of) and the load type can 
be modified. Any change to the component of 
the tribological system is reflected in the wear. 
Therefore, a detailed study of the wear mech-
anisms for a specific technological process (be 
it mechanised tunnelling, drilling, crushing or 
grinding of mineral raw materials) should be 
carried out, and on this basis an optimisation 
of the geometry and material of the tool in dy-
namic contact with the geological material and 
the type of loading should be carried out.
Two factors are of particular importance for 
a comprehensive understanding of tool wear. 
These are the wear rate and the mode of wear. 
In a comprehensive approach, the wear rate can 
be defined as the first stage and the wear mode 
as the second stage of wear investigation. Labo-
ratory test methods for assessing the abrasivity 
of rocks and soils are important because they 
allow the wear rate of tools that interact dy-
namically with the abrasive geological material 
to be determined. The wear rate can be deter-
mined immediately after the test is performed, 
for example, by weighing the loss of mass of the 
test specimen or by microscopic examination 
of the pin wear, depending on the test set-up. 
However, the second stage of the comprehen-
sive approach is to determine the mode of wear , 
which can be derived from the first stage.
This article presents a review of the laboratory 
tests to assess the abrasivity of rocks and soils, 
which are useful in the field of geotechnology 
and mining. These abrasivity tests can help us 
to gain a comprehensive understanding of tool 
wear, especially in the first stage, for determi-
nation of the wear rate. However, it is recom-
mended that starting from the first stage, the 
study of wear be continued in the second stage, 
which is concerned with determining the mode 
of wear. Compared to the first stage, the second 
stage is more demanding and time-consuming, 
as it requires interdisciplinary material knowl-
edge and several individual geochemical and 
metallurgical investigations at the microscopic 
level. A comprehensive approach to the investi-
gation of wear is the basis for the development 
of wear resistant tools and models for the pre-
diction of tool life in individual areas of geo-
technology and mining.
References
[1] Petrica, M., Painsi, M., Badisch, E., Peinsitt, T . (2014): 
Wear Mechanisms on Martensitic Steels Generated 
by Different Rock Types in Two-Body Conditions. 
Tribology Letters, 53(3), pp. 607–616, DOI: 10.1007/
s11249-014-0298-z.
[2] Golovanevskiy, V.A., Bearman, R.A. (2008): Gouging 
abrasion test for rock abrasiveness testing. Inter-
national Journal of Mineral Processing, 85(4), pp. 
111–120, DOI: 10.1016/j.minpro.2007.08.004.
[3] BBT Brenner Base Tunnel [online]. Galleria di Base 
del Brennero – Brenner Basistunnel BBT SE [cited 
3/5/2020]. Available on: https://www.bbt-se.com.
[4] Marti Group [online, cited 3/5/2020]. Available on: 
https://www.marti.com.
[5] Robbins [online]. The Robbins company 
[cited 3/5/2020]. Available on: https://www.
therobbinscompany.com.
[6] Krauze, K., Bołoz, Ł., Wydro, T . (2015): Parametric 
Factors for the Tangential-Rotary Picks Quality As-
sessment. Archives of Mining Sciences, 60(1), pp. 
265–281, DOI: 10.1515/amsc-2015-0018.
[7] Boart Longyear [online]. Boart Longyear company 
[cited 3/5/2020]. Available on: https://www.
boartlongyear.com.
[8] Varel [online]. Varel International Energy Services 
[cited 3/5/2020]. Available on: http://www.
vareloilandgas.com.
[9] Tkalich, D., Yastrebov, V.A., Cailletaud, G., Kane, A. 
(2017): Multiscale modeling of cemented tungsten 
carbide in hard rock drilling. International Journal 
of Solids and Structures, 128, pp. 282–295, DOI: 
10.1016/j.ijsolstr.2017.08.034.

Laboratory Test Methods for Assessing the Abrasivity of Rocks and Soils
15
[10] Yahiaoui, M., Paris, J.Y., Denape, J., Dourfaye, A. 
(2015): Multiscale and Comparative Study of WC-
Co Tribological Behavior. In: Procédés et Génie civ-
il: 27
ème
 Journées Internationales Francophones de 
Tribologie: JIFT, Nantes, France, Do, M.T., Cérézo, 
V., Kapsa, P. (eds.). Presses des Mines: Paris, pp. 
219–226.
[11] Cavpower [online, cited 3/5/2020]. Available on: 
https://www.cavpower.com.
[12] RWE [online]. RWE Group [cited 3/5/2020]. Avail-
able on: https://www.group.rwe.
[13] Blumaq [online, cited 3/5/2020]. Available on: 
https://www.blumaq.com.
[14] Sandvik [online, cited 3/5/2020]. Available on: 
https://www.rocktechnology.sandvik.
[15] Metso [online, cited 3/5/2020]. Available on: 
https://www.metso.com.
[16] Energosteel [online, cited 3/5/2020]. Available on: 
https://energosteel.com.
[17] Alber, M., Yarah, O., Dahl, F., Bruland, A., Käsling, H., 
Michalakopoulos, T.N., Cardu, M., Hagan, P., Aydin, 
H., Özarslan, A. (2013): ISRM Suggested Method for 
Determining the Abrasivity of Rock by the CERCHAR 
Abrasivity Test. Rock Mechanics and Rock Engineer-
ing, 47(1), pp. 261–266, DOI: 10.1007/s00603-013-
0518-0.
[18] Käsling, H., Thuro, K. (2010): Determining rock 
abrasivity in the laboratory. In: Rock mechanics in 
civil and environmental engineering: proceedings of 
the European Rock Mechanics Symposium (EURO-
CK) 2010, Lausanne, Switzerland, Zhao, J. (ed.). CRC 
Press: Leiden.
[19] Plinninger, R., Käsling, H., Thuro, K., Spaun, G. 
(2003): Testing conditions and geomechanical 
properties influencing the CERCHAR abrasiveness 
index (CAI) value. International Journal of Rock Me-
chanics & Mining Sciences, 40(2), pp. 259–263, DOI: 
10.1016/S1365-1609(02)00140-5.
[20] Aydin, H. (2019): Investigating the effects of various 
testing parameters on Cerchar abrasivity index and 
its repeatability. Wear, 418–419, pp. 61–74, DOI: 
10.1016/j.wear.2018.11.001.
[21] Thuro, K., Singer, J., Käsling, H., Bauer, M. (2006): 
Soil Abrasivity Assessment Using the LCPC Testing 
Device. Felsbau, 24(6), pp. 37–45, DOI: 10.1201/
NOE0415444019-c103.
[22] Dahl, F., Bruland, A., Jakobsen, P.D., Nilsen, B., 
Grøv, E. (2012): Classification of properties influ-
encing the drillability of rocks, based on the NTNU/
SINTEF test method. Tunnelling and Underground 
Space Technology, 28, pp. 150–158, DOI: 10.1016/j.
tust.2011.10.006.
[23] Jakobsen, P.D., Bruland, A., Dahl, F. (2013): Review 
and assessment of the NTNU/SINTEF Soil Abrasion 
Test (SAT
TM
) for determination of abrasiveness of 
soil and soft ground. Tunnelling and Underground 
Space Technology, 37, pp. 107–114, DOI: 10.1016/j.
tust.2013.04.003.
[24] Macias, F.J., Dahl, F., Bruland, A. (2016): New Rock 
Abrasivity Test Method for Tool Life Assessments 
on Hard Rock Tunnel Boring: The Rolling Indenta-
tion Abrasion Test (RIAT). Rock Mechanics and Rock 
Engineering, 49(5), pp. 1679–1693, DOI: 10.1007/
s00603-015-0854-3.