Cerchar Abrasion Ratio (CAR) as a New Indicator for Assessing Rock Abrasivity, Rock–Stylus Interaction and Cutting Efficiency

Zhang, Guangzhe; Konietzky, Heinz

doi:10.1007/s00603-020-02112-4

Cited by 10 publications

(5 citation statements)

References 16 publications

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“…As there exists a close relation between mineralogically induced abrasive tool wear, and fabric and weathering controlled strength, a holistic approach of the abrasivity assessment is required. The CERCHAR Abrasion Ratio (CAR) recently proposed by [48] seems a promising way of evaluating abrasivity in greater detail. Accounting for both stylus wear and the associated volumetric removal of material from the rock, information on excavability is added to the CERCHAR test.…”

Section: Discussion and Interpretationmentioning

confidence: 99%

Hardness, strength and abrasivity of rocks: Correlations and predictions

Kaspar

Latal

Pittino

et al. 2023

Geomechanics and Tunnelling

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Since ancient times, rocks and their geomechanical and mineralogical properties have played a fundamental role for realising construction and infrastructure projects. Workability and excavability of the material itself are still decisive factors controlling tool wear and advancement rates. In engineering geology, standardised tests and analyses related to the strength, hardness, abrasivity and mineralogical composition are commonly conducted in this context. The uniaxial compressive strength (UCS), CERCHAR Abrasivity Index (CAI) and equivalent quartz content are widely used parameters for such an assessment, in order to estimate and predict drillability and associated wear of drill bits, cutting discs or chisels. In this article, the correlations between strength, abrasivity and mineral content of various rock types are investigated. The concept of hardness in geotechnics and engineering geology is elaborated in greater detail, shedding light on hardness definitions, testing methods and how hardness parameters are interrelated. Under the aspect that the CAI shows a good correlation with the Mohs hardness commonly used in mineralogy, a novel approach for estimating the CAI is presented. It is suggested that the CAI of a rock can be estimated within 50 % of the actual value, if its UCS exceeds »60 MPa. On the data basis of various rock types analysed from national and international construction projects, the potential and limitations of this method are discussed.

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Section: Discussion and Interpretationmentioning

confidence: 99%

Hardness, strength and abrasivity of rocks: Correlations and predictions

Kaspar

Latal

Pittino

et al. 2023

Geomechanics and Tunnelling

View full text Add to dashboard Cite

show abstract

“…Figure 6-5 exhibits the impact of thermal treatment on the P-wave velocity and the effect of cooling rate on the CAI value but does not directly reflect the stylus and rock interaction. The Cerchar abrasion ratio (CAR), defined as the ratio of the rock removal volume (Vr) to the stylus wear volume (Vs), reveals the stylus and rock interaction, in terms of volume variation (Zhang and Konietzky, 2020):…”

Section: Discussionmentioning

confidence: 99%

“…However, the penetration depth may not be accurately estimated in this case, because rock fragments may exist before the scratch and fill in the trench after the scratch. According to the empirical relation between the CAR and CAI values for a smooth surface (Zhang and Konietzky, 2020), CAR = -0.628 CAI + 4.463, the CAR value is also related to the wear flat, as the CAI value is determined as 10 × d. Therefore, the wear flat is a key parameter to evaluate the stylus and rock interaction.…”

Section: Discussionmentioning

confidence: 99%

“…The estimation of the cutting-tool wear relies most on Cerchar abrasivity index (CAI) tests, and the determination of rock abrasivity is commonly based on the CAI value (Alber et al, 2014). As one of the characteristic rock properties, rock abrasivity is essential to evaluate the tool wear, energy consumption, and cutting duration in underground excavation (Zhang and Konietzky et al, 2020;Zhang et al, 2020a).…”

Section: List Of Tablesmentioning

confidence: 99%

“…The CAI value is also correlated to the compressive and shear strengths of corresponding rocks (Deliormanlı, 2012;Er and Tuğrul, 2016). The rock-stylus interaction is estimated based on the rock removal volume and the stylus wear volume (Zhang and Konietzky, 2020), and the efficiency of rock scratching is reflected by the stretching specific energy (Zhang et al, 2020a and. Machine learning approaches can be additionally applied to predict the CAI value according to the rock's mechanical properties, such as P-wave velocity, uniaxial compressive strength, and Young's modulus (Tripathy et al, 2015).…”

Section: Cerchar Abrasivity Index Testmentioning

confidence: 99%

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Evolution of rock brittleness under mechanical and thermal effects

Wang¹

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Experimental investigation of abrasive potential and drilling efficiency at elevated temperatures via Cerchar rock scratching

Zhang,

Konietzky,

Frühwirt

2024

Geomech. Geophys. Geo-energ. Geo-resour.

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To see if and how abrasive potential as well as drilling efficiency change due to rock heating, Cerchar scratch tests were performed on six types of rock at eight temperature levels. Results indicate that rock abrasivity is temperature-dependent. The change of rock abrasivity expressed by the Cerchar abrasivity index can be divided into two stages on either side of 500 °C. Meanwhile, the drilling efficiency expressed by the Cerchar abrasion ratio can significantly be enhanced, especially when the heating temperature exceeds 500 °C. The observation of damaged surfaces indicates that the material volume removed from the rock surface increase after rock heating. The worn steel surfaces (115CrV3 tool steel) shows the severe plastic deformation and fracturing associated with cracking, delamination, dislocation and chipping of the steel.

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Cerchar Abrasion Ratio (CAR) as a New Indicator for Assessing Rock Abrasivity, Rock–Stylus Interaction and Cutting Efficiency

Cited by 10 publications

References 16 publications

Hardness, strength and abrasivity of rocks: Correlations and predictions

Hardness, strength and abrasivity of rocks: Correlations and predictions

Evolution of rock brittleness under mechanical and thermal effects

Experimental investigation of abrasive potential and drilling efficiency at elevated temperatures via Cerchar rock scratching

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