Influence of planes of anisotropy on physical and mechanical properties of freshwater limestone (Mudstone)

Abstract

The formation of the freshwater lakes and travertine limestone was caused by the tectonic depression, which occurred in the Dinarides during the Miocene. This stone has been exploited and used since far back on the territory of Bosnia and Herzegovina as a building stone and for different architectural purposes. Most of the investigations were concentrated on the “tenelija” stone due to its massive use and construction of the famous Stari Most (Old Bridge) in Mostar. Not much investigation was devoted to “miljevina” (mudstone) which belongs to the same petrographic type. This is a soft carbonate rock that is highly porous, has small density, relatively low strengths, poor wear resistance, and low resistance to frost. In this paper, the influence of layers (planes of anisotropy - foliation) of the mudstone was investigated. Within an experimental campaign, numerous sets of tests were performed on different samples. Tests include uniaxial compressive strength (UCS) on cube and cylinder specimens, flexural strength under concentrated load and constant moment, tensile strength based on Brazilian tests, determination of Young’s modulus, modulus of deformations, and Poisson ratio. Prediction of UCS and Young’s modulus, as elastic mechanical characteristics, represent the main goal in engineering projects. Additionally, the influence of sample conditions and planes of anisotropy was investigated. Results have been compared and correlations are established. As a result, a new relation between uniaxial compressive strength obtained on cube and cylinder samples for a stone of low compressive strength is proposed.