Density Index and relative compaction

Learn Density Index, relative compaction, density index and void ratio relationship,charectristics of granular soils in dense and loose states,Relative density Density Index The term density index ID or relative density or degree of density is used to express the relative compactness (or degree of compaction) of a natural cohesionless soil deposit. The density index is defined as the ratio of the difference between the voids ratio of the soil in its loosest state emax and its natural voids ratio e to the difference between the voids ratios in the loosest and densest states: \[I_{D} = \frac{e_{max}-e}{e_{max}-e_{min}}.                  (1)\] where emax = voids ratio in the loosest state emin = voids ratio in the densest state e = natural voids ratio of the deposit. This term is used for cohesionless soil only. This term is not applicable to cohesive soil because of uncertaintities in…

Continue Reading Density Index and relative compaction

Voids ratio porosity degree of saturation

Learn voids ratio, porosity, degree of saturation, percentage air voids, Air content Voids ratio. Voids ratio e of a given soil sample is the ratio of the volume of voids to the volume of soil solids in the given soil mass. \[e= \frac{V_{v}}{V_{s}}\] Porosity. The porosity n of a given soil sample is the ratio of the volume of voids to the total volume of the given soil mass \[n = \frac{V_{v}}{V}\] The voids ratio e is generally expressed as a fraction, while the porosity n is expressed as a percentage and is, therefore, also referred to as percentage voids. Figure (a) shows the soil element in terms of voids ratio e. If the volume of voids is taken equal to e, the volume of solids, by definition equation would be equal to 1, and the total volume equal to (1 + e). Similarly, if the volume of the voids…

Continue Reading Voids ratio porosity degree of saturation

Absolute or true specific gravity

Learn specific gravity, Absolute or true specific gravity, Table of specific gravity of soil constituent Specific gravity  Specific gravity is defined as the ratio of the weight of a given volume of soil solids at a given temperature to the weight of an equal volume of distilled water at that temperature, both weights being taken in air. In other words, it is the ratio of the unit weight of soil solids to that of water. \[G = \frac{\gamma_{s}}{\gamma_{w}}\] The Indian Standard specifies 27°C as the standard temperature for reporting the specific gravity. Some qualifying words like: true, absolute, apparent, bulk or mass, etc., are sometimes added to the term ‘specific gravity’. These qualifying words modify the sense of specific gravity as to whether it refers to soil particles or to soil mass. The soil solids have permeable and impermeable voids inside them, the permeable voids being capable of getting filled with…

Continue Reading Absolute or true specific gravity