Void ratios

Void ratio (e) is defined as the volume of voids (Vy) to the volume of solids (Vg), 

Void ratio (e) can also be calculated from water content (w), the density of solids (pj derived above, and the density of pore water (p ) for a saturated condition can thus be calculated as given below  

Then rewriting Equation 6.39 gives the following relation, 

For uniform solid and pore fluid densities under saturated conditions, void ratio is simply a function of the water content. 

11 Description of Mass-Volume with Correction for Salt Content in Soils 

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The amount of material in a mill can be expressed conveniently as the ratio of its volume to that of the voids in the ball load. This is known as the material-to-void ratio. If the solid material and its suspending medium (water, air, etc.) just fill the ball voids, the ratio is 1, for example. Grinding-media loads vary from 20 to 50 percent in practice, and ratios are usually near 1. 

Relative density (a percent) is a measure of the compactness of a soil with void ratio e when the maximum void ratio is e and the minimum Relative density is... 

In the past, various resin flow models have been proposed [2,15-19], Two main approaches to predicting resin flow behavior in laminates have been suggested in the literature thus far. In the first case, Kardos et al. [2], Loos and Springer [15], Williams et al. [16], and Gutowski [17] assume that a pressure gradient develops in the laminate both in the vertical and horizontal directions. These approaches describe the resin flow in the laminate in terms of Darcy s Law for flow in porous media, which requires knowledge of the fiber network permeability and resin viscosity. Fiber network permeability is a function of fiber diameter, the porosity or void ratio of the porous medium, and the shape factor of the fibers. Viscosity of the resin is essentially a function of the extent of reaction and temperature. The second major approach is that of Lindt et al. [18] who use lubrication theory approximations to calculate the components of squeezing flow created by compaction of the plies. The first approach predicts consolidation of the plies from the top (bleeder surface) down, but the second assumes a plane of symmetry at the horizontal midplane of the laminate. Experimental evidence thus far [19] seems to support the Darcy s Law approach. 

Figure 1. General diagram of the shrinkage curve and its derivatives. On the horizontal axis is the moisture ratio (volume of water per unit volume of solids, dimensionless). On the vertical axis is, for the solid line (the shrinkage curve), the void ratio (volume of voids per unit volume of solids, dimensionless), and, for the broken line, the value of the slope of the shrinkage curve (dimensionless), and, for the dotted line, the absolute value of the curvature of the shrinkage curve (dimensionless). The following values were used for the parameters k. = 2, k. = 1.6, n = 1.6, and e = 1.9.

The swelling pressure II is, under saturated conditions, a function of the void ratio e according to... 

The void ratio at air entry eae is a function of the load pressure P and the void ratio eaeo at air entry for P = 0, according to... 

The modulus is also said to be a measure of the voids ratio. It has a maximum value of 1 for uniform material, and smaller values if finer or coarser materials are added. When the voids between the large particles are filled with smaller particles the modulus decreases. However, it is hard to conceive that Kramer s modulus is any more suited to such representation than the standard deviation. 

As indicated by eqn. (4) (Section 2.1), the main variables affecting the strength of an agglomerate, other than the bonding mechanism, are the void ratio and the size of the particles from which it is composed. A number of empirical relationships have been used to correlate the effects of these variables. For example, eqn. (18) has been used [39] to represent the crushing strength of compressed tablets of constant size. 

A high volume of powder feed produces a cushioning effect whereas small sample volumes cause a loss of efficiency and abrasive wear of the mill parts. The amount of material to be milled in a ball mill may be expressed as a material-to-void ratio (ratio of the volume of material to that of the void in the ball charge). As the amount of material is increased, the efficiency of a ball mill is increased until the void space in the bulk volume of ball charge is filled then, the efficiency of milling is decreased by further addition of material. 

The value of of a powder depends on many factors, such as particle size, particle shape, void ratio and kind of the gas existing among particles of the powder, as well as kind of the original solid. 

Example Stage Vol.% solids Void ratio (volume of liquid/ volume of solid) Liquid removed (volume of liquid/ volume of solid) Liquid removed (%) Total liquid removed (%)... 

Specific gravity of solids Necessary for hydrometer analysis, void ratio, and density calculations... 

Figure 2.1 is a pictorial representation of the void ratio. Void ratios for granular soils range from 0.4 to 0.8. Clays and clayey soils will range from 0.5 to 1.5 or 2.0. Soils with high organic content, peats and mucks, may have void ratios as high as 4 or 5. 

Figure 2.1 Relationships to define void ratio and porosity.

Description Porosity, n %) Void ratio, e Water contents Wsaf (%) Unit weight ... 

Void ratio Porosity Soils Grain size (mm) Permeability (cm/s)... 

Action of a differential soil mass similar to a large soil mass Linear relationship between pressure and void ratio over a small range... 

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