The eleven varieties of basalt from Central India, comprising eight fresh, i.e., grade I, and one each of weathering grades II, III, and IV, have been evaluated in the laboratory, and their recommended properties and parameters are arranged in a Table under four categories, namely, weathering and water-related properties (weathering grade, water content, porosity, porosity class, and slake durability index), densities (dry bulk, saturated bulk and grain), waves" velocities (compression and shear, both, in dry and saturated, both states), and strength and deformability characteristics (uniaxial compressive strength, Tangent modulus, Poisson"s ratio and tensile strength). From left-to-right, the variants of basalt are arranged in accordance with improving grade of weathering/ decreasing water content/ increasing slake durability index/ increasing dry bulk density, in that order. The patterns of relationship emerge; and, there is fairly good correlation between slake durability index and porosity, dry bulk density and porosity, UCSsat and a derived quantity of waves" velocities, and tangent modulus and Vp(sat).


As per ISRM Suggested Methods (1), the basalt"s eleven variants, comprising different weathering grades - fresh, slightly-, moderately-, and highly-, weathered - from Central India, were assessed in the laboratory; and the data contained in CSMRS" reports (2, 3, 4, 5) enables study of response patterns of three kinds. One is the intra-relationship between different properties/ parameters of a given variant of basalt - in the backdrop of the rest of the data. Two, the emerging patterns of relations between different properties/ parameters of fresh basalts are noted. Three, as the investigated basalts represent different grades of weathering (I, II, III, and IV), a qualitative-, and in some cases quantitative-, patterns in responses, over the above-mentioned range of weathering grades, reveal themselves. Table 1 contains recommended properties and parameters of eleven variants of basalt from central India. Each of this represents several specimens of a particular basalt, which have been tested - in accordance with ISRM Suggested Methods - for a given property or parameter; and, notwithstanding that the inherent variability or scatter in the test data of rock (treated as one variant), especially for parameters such as waves" velocities and strength and deformability characteristics, is a commonly observed phenomenon, and was in evidence here as well, a discussion on the variability in the test data for each of these basalts for the investigated properties and parameters is not discussed, nor even mentioned, in this paper. In order to discern patterns, the first crucial step, explained in this section, is to thoughtfully arrange the recommended properties and parameters of eleven variants of basalt. The data is classified under four categories - namely, weathering and water-related properties, densities, waves" velocities, and strength and deformability characteristics - and, presented in the same order in Table 1. In the first category, weathering grade, water content, apparent porosity, and slake durability index are the included properties in descending order. The second category of density includes dry bulk density (and density class), saturated bulk density and grain density.

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