Mechanical behavior of bimrocks having high rock block proportion

•Physical model bimrocks (block-in-matrix rocks) having high rock block proportion were tested under servo-controlled uniaxial compression.•A decreasing trend in UCS, Young's modulus and failure strain were observed with increasing the rock block proportion.•Increasing the rock block proportion of the specimens made the post-peak behavior gentler.•Dominant failure mode of the specimens under uniaxial compression were multiple tortuous failure surfaces.

Determination of mechanical behavior of geomaterials composed of block-in-matrix texture, particularly having high rock block content, is a challenging task for engineers. In literature, these heterogeneous materials also referred as bimrock (block-in-matrix rock). Preparation of undisturbed and representative samples of these materials is often extremely difficult. Fabrication of artificial (physical) model specimens in laboratory can be used to overcome this difficulty and to study the mechanical behavior of bimrocks. Physical model bimrocks were prepared by stiffer rock blocks which were comprised 70–90% of the total weight, plus a softer cementing agent. Using a servo-control machine, uniaxial compression tests were conducted on model bimrocks to obtain the mechanical parameters such as uniaxial compressive strength (UCS), Young's modulus, failure strain and full-scale stress–strain curves. The results showed a decreasing trend with exponential correlation in the UCS, Young's modulus and failure strain of specimens with increasing the rock block proportion (RBP). In the post-peak region of stress–strain curves, strain softening was the dominant behavior and increasing RBP values in the specimens made the post-peak behavior gentler.