Abrasivity database of different genetic rocks based on CERCHAR Abrasivity Test

Rock abrasivity is one of the main factors affecting the wear of rock-cutting tools, which is usually quantified by the CERCHAR Abrasivity Index (CAI). Researchers and engineers study tool

wear and predict tool life based on the CAI of rocks. However, there is still a lack of a dataset on rock properties, especially the abrasivity of various rocks. This paper reports the

abrasive dataset of 10 kinds of rocks, including sedimentary rocks, metamorphic rocks, and igneous rocks, with the aid of the CERCHAR Abrasivity Test and digital measurement techniques. The

dataset comprises rock abrasivity data, point cloud data for visualization, scratch photos, CERCHAR Abrasivity Test force data, and mechanical properties (uniaxial compressive strength) of

rock samples. This dataset facilitates future research on rock abrasivity and rock-cutting tool wear.

Mechanically, rock cutting refers to the process of applying force to the rock through the tool to break the rock. Featured by high excavation efficiency and safety, rock cutting is widely

used in mining, tunnelling, and construction industries1,2. Nevertheless, tool wear is a significant issue in mechanical rock breaking, as it leads to the removal or displacement of cutter

material during rock excavation3. This wear on the tools greatly increases construction costs, and affects the entire construction period4.

Taking tunnel construction as an example, more than 60% of the world’s tunnels are excavated by tunnel boring machines (TBM) (2013)5. Studies have shown that when a TBM was adopted to tunnel

hard rock strata with huge thrust, the tool would wear rapidly6. If construction workers do not replace the worn tools on time, the wear rate of the remaining unworn tools and the number of

abnormally worn tools will sharply increase, severely lowering excavation efficiency and tool utilization rate7. Even if construction personnel can accurately identify the current wear of

cutting tools and replace them on time, tool replacement is still a time-consuming activity that has a significant impact on the daily advance rate (AR) and thus on the time and cost of

tunnel construction8. According to statistical data, 20% of the project’s construction costs go toward replacing cutters, and their replacement takes up 30% of the project’s total excavation

time9.

Abrasivity describes the ability of rocks (minerals) to wear (frictionally) the surface of solid materials, which reflects the degree of wear of the material interacting with it10.

For any rock excavation project, estimating wear costs is a very challenging task11. Research on the abrasivity of rocks is conducive to comprehending the mechanism of rock abrasivity,

choosing the applicable excavation equipment12, and reducing excavation costs.

CAI is an index for measuring the rock’s abrasivity via the CERCHAR Abrasivity Test3. Rock abrasivity matters a lot in the fields of mining, drilling, tunnelling, and construction

materials3,13,14,15. In the 1970s, the CERCHAR Abrasivity Test was first developed by the Laboratoire du Centre d’Études et Recherches des Charbonnages (CERCHAR) de France3, whose

experimental set-up is shown in Fig. 1. Specifically, the CERCHAR-type testing apparatus3 is presented in Fig. 1a, and the modified apparatus configuration used here is shown in Fig. 1b.

CAI test apparatus. (a) Schematic diagram of the CERCHAR-type apparatus and (b) Schematic diagram of the modified CERCHAR apparatus employed herein.

Although the abrasivity of rocks has been vigorously explored14,15,16,17,18, rock samples used for testing come from various mining areas in the world, with different properties. Studies

have shown that the abrasivity of rocks is related to the mechanical properties of rocks, and the content of quartz and other abrasive minerals11,19,20. Additionally, when the CERCHAR

Abrasivity Test is carried out, the normal force applied to the stylus and the skills of the person performing the test will also affect the CAI value18,21,22. Therefore, it is necessary to

take the aforementioned factors into account rather than just resorting to the CERCHAR Abrasivity Test alone.

Taking that into consideration, under four different normal forces, the CERCHAR Abrasivity Test is performed in the present study using the computerized CAI tester (Fig. 2). A servo press

(Fig. 3) is utilized for testing the mechanical properties of rock samples. By means of the laser measuring system shown in Fig. 4, the rock’s scratches are measured and recorded in digital

camera pictures. The elemental analysis is carried out by X-ray fluorescence (XRF). A brief overview is provided in Fig. 5.

Computerized CAI tester and partial diagram (The principle of the computerized CAI tester is the same as the modified CERCHAR apparatus).

Laser measurement system (laser confocal microscope and computer).

In this study, four different normal forces are applied in the CERCHAR Abrasivity Test to 10 different rocks, including igneous rocks, sedimentary rocks, and metamorphic rocks. Additionally

included are the force data collected during the testing, wear data from 40 sets of styluses, pictures, mechanical properties data from rocks, XRF data, and x-ray diffraction (XRD) data.

This paper is highly valuable for researching the tool wear, the mechanism of rock abrasivity, as well as the CERCHAR Abrasivity Test.

This section describes the rock sample information (source, mechanical properties, composition) used in the CAI test, the specific details of the CERCHAR Abrasivity Test (experimental

equipment, test steps, etc.), and the acquisition process of the rock surface point cloud data after the test.

In the fields of construction, road, and mining, it is often necessary to break marble, granite, sandstone, and other rocks. In the tunnelling process of some hard rock tunnels,

difficult-to-break basalt may also exist. Cutting these rocks will cause wear and tear to the cutting tools. For this rock abrasivity study, we obtained a variety of igneous, sedimentary,

and metamorphic rocks from quarries in different parts of China as given in Fig. 6. The rock samples were obtained from open-pit mines within 100 m of the surface. Geological information on

each of the mining areas can be found in the literature23,24,25,26,27,28,29,30,31,32,33,34,35,36.

The length to diameter ratio of the samples utilized for the test is 2:1 (diameter: 50 mm, length: 100 mm). In the study, all test samples have a homogeneous and isotropic rock matrix that

lacks visible pores or fractures. To ensure the comparability of the results, the coring direction of the sandstone is parallel to the normal of the sedimentary surface. Ten rock samples

have been selected for the test. Basalt samples are fine-grained rocks (