1. Density, Porosity and Water Content:-
Density is a measure of mass per unit of volume. Density of rock material various, and often related to the porosity of the rock. It is sometimes defined by unit weight and specific gravity. Most rocks have density between 2,500nd 2,800 kg/m3.
Porosity describes how densely the material is packed. It is the ratio of the non-solid volume to the total volume of material. Porosity therefore is a fraction between 0 and 1. The value is typically ranging from less than 0.01 for solid granite to up to 0.5 for porous sandstone. It may also be represented in percent terms by multiplying the fraction by 100%. Water content is a measure indicating the amount of water the rock material contains. It is simply the ratio of the volume of water to the bulk volume of the rock material.
Density is common physical properties. It is influenced by the specific gravity of the composition minerals and the compaction of the minerals. However, most rocks are well compacted and then have specific gravity between 2.5 to 2.8. Density is used to estimate overburden stress. Density and porosity often related to the strength of rock material. A low density and high porosity rock usually has low strength. Porosity is one of the governing factors for the permeability. Porosity provides the void for water to flow through in a rock material. High porosity therefore naturally leads to high permeability.
2. Hardness:-
Hardness is the characteristic of a solid material expressing its resistance to permanent deformation. Hardness of a rock materials depends on several factors, including mineral composition and density. A typical measure is the Schmidt rebound hardness number.
3. Abrasivity:-
Abrasivity measures the abrasiveness of a rock materials against other materials, e.g.,steel. It is an important measure for estimate wear of rock drilling and boring
equipment.Abrasivity is highly influenced by the amount of quartz mineral in the rock material.The higher quartz content gives higher abrasivity.Abrasivity measures are given by several tests.
4. Permeability:-Permeability is a measure of the ability of a material to transmit fluids. Most rocks, including igneous, metamorphic and chemical sedimentary rocks, generally have very low permeability. As discussed earlier, permeability of rock material is governed by porosity. Porous rocks such as sandstones usually have high permeability while granites have low permeability. Permeability of rock materials, except for those porous one, has limited interests as in the rock mass, flow is concentrated in fractures in the rock mass. Permeability of rock fractures is discussed later.
5. Wave Velocity:-
Measurements of wave are often done by using P wave and sometimes, S waves. P- wave velocity measures the travel speed of longitudinal (primary) wave in the material, while S-wave velocity measures the travel speed of shear (secondary) wave in the material. The velocity measurements provide correlation to physical properties in terms of compaction degree of the material. A well compacted rock has generally high
velocity as the grains are all in good contact and wave are travelling through the solid.
For a poorly compact rock material, the grains are not in good contact, so the wave will partially travel through void (air or water) and the velocity will be reduced (P-wave velocities in air and in water are 340 and 1500 m/s respectively and are much lower than that in solid).
Density is a measure of mass per unit of volume. Density of rock material various, and often related to the porosity of the rock. It is sometimes defined by unit weight and specific gravity. Most rocks have density between 2,500nd 2,800 kg/m3.
Porosity describes how densely the material is packed. It is the ratio of the non-solid volume to the total volume of material. Porosity therefore is a fraction between 0 and 1. The value is typically ranging from less than 0.01 for solid granite to up to 0.5 for porous sandstone. It may also be represented in percent terms by multiplying the fraction by 100%. Water content is a measure indicating the amount of water the rock material contains. It is simply the ratio of the volume of water to the bulk volume of the rock material.
Density is common physical properties. It is influenced by the specific gravity of the composition minerals and the compaction of the minerals. However, most rocks are well compacted and then have specific gravity between 2.5 to 2.8. Density is used to estimate overburden stress. Density and porosity often related to the strength of rock material. A low density and high porosity rock usually has low strength. Porosity is one of the governing factors for the permeability. Porosity provides the void for water to flow through in a rock material. High porosity therefore naturally leads to high permeability.
2. Hardness:-
Hardness is the characteristic of a solid material expressing its resistance to permanent deformation. Hardness of a rock materials depends on several factors, including mineral composition and density. A typical measure is the Schmidt rebound hardness number.
3. Abrasivity:-
Abrasivity measures the abrasiveness of a rock materials against other materials, e.g.,steel. It is an important measure for estimate wear of rock drilling and boring
equipment.Abrasivity is highly influenced by the amount of quartz mineral in the rock material.The higher quartz content gives higher abrasivity.Abrasivity measures are given by several tests.
4. Permeability:-Permeability is a measure of the ability of a material to transmit fluids. Most rocks, including igneous, metamorphic and chemical sedimentary rocks, generally have very low permeability. As discussed earlier, permeability of rock material is governed by porosity. Porous rocks such as sandstones usually have high permeability while granites have low permeability. Permeability of rock materials, except for those porous one, has limited interests as in the rock mass, flow is concentrated in fractures in the rock mass. Permeability of rock fractures is discussed later.
5. Wave Velocity:-
Measurements of wave are often done by using P wave and sometimes, S waves. P- wave velocity measures the travel speed of longitudinal (primary) wave in the material, while S-wave velocity measures the travel speed of shear (secondary) wave in the material. The velocity measurements provide correlation to physical properties in terms of compaction degree of the material. A well compacted rock has generally high
velocity as the grains are all in good contact and wave are travelling through the solid.
For a poorly compact rock material, the grains are not in good contact, so the wave will partially travel through void (air or water) and the velocity will be reduced (P-wave velocities in air and in water are 340 and 1500 m/s respectively and are much lower than that in solid).
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