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Experimental study of the mechanical behavior of oriented bimrocks under diametral compression test using DIC
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  • Published: 20 February 2026

Experimental study of the mechanical behavior of oriented bimrocks under diametral compression test using DIC

  • Reza Rostamlo-Jooshin1,
  • Mojtaba Bahaaddini1 &
  • Mohammad Hossein Khosravi2 

Scientific Reports , Article number:  (2026) Cite this article

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We are providing an unedited version of this manuscript to give early access to its findings. Before final publication, the manuscript will undergo further editing. Please note there may be errors present which affect the content, and all legal disclaimers apply.

Subjects

  • Engineering
  • Materials science
  • Solid Earth sciences

Abstract

Block-in-matrix rocks (Bimrocks) are complex geomaterials consisting of strong rock blocks embedded in a weaker matrix, exhibiting highly heterogeneous mechanical behavior. Understanding their mechanical properties—particularly tensile strength and fracture mechanisms—remains challenging for geotechnical engineers in design of surface and underground structures. The orientation of rock blocks, which forms during Bimrock genesis, can significantly influence their mechanical behavior. This study investigates the effect of block orientation on the tensile response of Bimrocks using diametral compression (Brazilian) tests, supported by digital image correlation (DIC) to analyze strain localization, crack initiation, and propagation patterns. Synthetic Bimrock specimens with controlled volumetric block proportions (VBP) and block orientations were prepared and tested. Given the material’s heterogeneity and data scatter, response surface methodology (RSM) and analysis of variance (ANOVA) were employed for statistical evaluation. Results indicate that the peak load decreases sharply from pure matrix specimens to those with 12.5% VBP, followed by a slower decline at higher VBPs. Increasing block orientation relative to the loading direction significantly enhances peak load resistance, particularly at higher VBPs. DIC analysis revealed that higher VBPs promote crack initiation away from the disc center, with multiple strain localization zones observed at 50% VBP. The study demonstrates that the Brazilian test yields invalid tensile strength estimates at high VBPs, and even at low VBPs, results depend critically on block size and orientation. These findings underscore the anisotropic tensile behavior of Bimrocks and highlight the limitations of conventional testing methods for heterogeneous materials.

Data availability

The datasets analyzed during the current study available from the corresponding author on reasonable request.

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Funding

The authors declare that this research was carried out without any specific funding.

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Authors and Affiliations

  1. School of Mining Engineering, College of Engineering, University of Tehran, Tehran, Iran

    Reza Rostamlo-Jooshin & Mojtaba Bahaaddini

  2. Department of Mining Engineering, Faculty of Engineering, University of Birjand, Birjand, Iran

    Mohammad Hossein Khosravi

Authors
  1. Reza Rostamlo-Jooshin
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  2. Mojtaba Bahaaddini
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  3. Mohammad Hossein Khosravi
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Contributions

Methodology: R. Rostamlo-Jooshin, M. Bahaaddini; Conceptualization: M. Bahaaddini, M.H. Khosravi; Investigation: R. Rostamlo-Jooshin, M. Bahaaddini; Visualization: R. Rostamlo-Jooshin, M. Bahaaddini; Validation: R. Rostamlo-Jooshin, M. Bahaaddini, M.H. Khosravi; Supervision: M. Bahaaddini, M.H. Khosravi; Formal analysis: R. Rostamlo-Jooshin, M. Bahaaddini; Writing—original draft: R. Rostamlo-Jooshin, M. Bahaaddini; Writing—review & editing: M.H. Khosravi.

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Correspondence to Mojtaba Bahaaddini.

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Rostamlo-Jooshin, R., Bahaaddini, M. & Khosravi, M.H. Experimental study of the mechanical behavior of oriented bimrocks under diametral compression test using DIC. Sci Rep (2026). https://doi.org/10.1038/s41598-026-40334-8

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  • Received: 14 December 2025

  • Accepted: 12 February 2026

  • Published: 20 February 2026

  • DOI: https://doi.org/10.1038/s41598-026-40334-8

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Keywords

  • Block in matrix rock (bimrock)
  • Block orientation
  • Volumetric block proportion (VBP)
  • Brazilian test
  • Digital image correlation (DIC)
  • Response surface methodology (RSM)
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