Different authors have used synthetic rocks to perform rock mechanics experiments or to assess petrophysical properties under well-known material conditions. In contrast with naturally cohesive materials, synthetic rocks provide with some opportunities to standardize mineralogy, grain size and morphology as well as the possibility to enhance certain rock features (e.g. anisotropy) useful to test or improve rock physical models. Typically, synthetic rocks are made of minerals grains bound together by a gluing agent that may be an organic adhesive (epoxy-like), cement or a nearly-saturated silica solution. However, most of the available works reporting synthesis of artificial rocks in the literature do not present a comprehensive framework for, at least: a) How the manufacturing process was performed and what are the associated implications; b) the characterization of the physical and hydrodynamic properties of the final products; and c) an assessment about the consistency of rock-related results ( i.e. homogeneity, reproducibility) from the artificial rocks.

In this contribution we present a methodology for the design, manufacturing and characterization of sandstone-like synthetic rocks. Sandstone-like plugs have been fabricated using homogeneous-size glass bead grains that have been compressed to a load limited by grain fragmentation (as recorded by simultaneous acoustic emissions). Sodium metasilicate and kaolinite were used as proto-binding agents. Cementation occurred as a result of direct chemical reactions and the submission of the samples to different thermal treatment paths. The plugs obtained have been tested in order to determine properties like density, porosity, specific surface, strength, and ultrasonic velocities ( V_p and V_s) and their corresponding variabilities.

The study of thermo-hydro-mechanical-chemical (THMC) coupled processes in rocks is relevant for a variety of research fields, such as radioactive waste management, exploration/exploitation of fossil fuels, or CO₂ geosequestration. Numerical models can be useful to analyse coupled processes but, by themselves, they are not able to fully represent the wealth of complexities of natural rocks. For this reason, the experimental approach is (and will be) critical to better understand the scope and impact of THMC processes in geological systems. The heterogeneous and anisotropic nature of many rock materials challenges the applicability of experimental results to tasks such as the calibration of numerical models and makes difficult also the upscaling of lab data to field properties or even the direct comparison of observations and processes at the corresponding scale. While significant advances in the study of the different rock properties ( e.g. hydrodynamics in continuous or fractured media, petrophysics, geomechanics, etc.) have been reported along the past decades, it persists a significant gap of knowledge concerning the impact of coupled processes over them ( e.g. chemical reactivity in connection with changes in the poroelastic behaviour; Vanorio 2015). The manufacturing and use of synthetic rock analogues in coupled-processes experimentation constitutes an attractive approach if realistic specimens with reproducible and contrastable properties are available.