Particle size and porosity relationship

particle size and porosity relationship

Particles' shapes and sizes affect how they aggregate, including how tightly they can pack together, which affects a rock's porosity—a property. The pore size increases the ability of the media to pass on through it more quantity of fluid, compared to some What is the effect of grain size on Porosity? Is there a relation between measuring the moisture of soil and the porosity of it ?. Relationship between Particle Size Distribution and Porosity in. Dump Leaching by. Shuo Zhang., The University of Waterloo, A Thesis Submitted in.

Porosity and hydraulic conductivity[ edit ] Porosity can be proportional to hydraulic conductivity ; for two similar sandy aquifers, the one with a higher porosity will typically have a higher hydraulic conductivity more open area for the flow of waterbut there are many complications to this relationship.

The principal complication is that there is not a direct proportionality between porosity and hydraulic conductivity but rather an inferred proportionality. There is a clear proportionality between pore throat radii and hydraulic conductivity.

Also, there tends to be a proportionality between pore throat radii and pore volume. If the proportionality between pore throat radii and porosity exists then a proportionality between porosity and hydraulic conductivity may exist. However, as grain size or sorting decreases the proportionality between pore throat radii and porosity begins to fail and therefore so does the proportionality between porosity and hydraulic conductivity.

Sorting and porosity[ edit ] Effects of sorting on alluvial porosity.

Porosity - Wikipedia

Black represents solids, blue represents pore space. Well sorted grains of approximately all one size materials have higher porosity than similarly sized poorly sorted materials where smaller particles fill the gaps between larger particles. The graphic illustrates how some smaller grains can effectively fill the pores where all water flow takes placedrastically reducing porosity and hydraulic conductivity, while only being a small fraction of the total volume of the material.

For tables of common porosity values for earth materialssee the "further reading" section in the Hydrogeology article. Porosity of rocks[ edit ] Consolidated rocks e. This can be split into connected and unconnected porosity. Connected porosity is more easily measured through the volume of gas or liquid that can flow into the rock, whereas fluids cannot access unconnected pores.

Porosity is the ratio of pore volume to its total volume.

particle size and porosity relationship

Porosity is controlled by: Porosity is not controlled by grain size, as the volume of between-grain space is related only to the method of grain packing. Rocks normally decrease in porosity with age and depth of burial. Tertiary age Gulf Coast sandstones are in general more porous than Cambrian age sandstones.

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There are exceptions to this rule, usually because of the depth of burial and thermal history. Porosity of soil[ edit ] Main article: Porosity of soil Porosity of surface soil typically decreases as particle size increases.

particle size and porosity relationship

This is due to soil aggregate formation in finer textured surface soils when subject to soil biological processes. Aggregation involves particulate adhesion and higher resistance to compaction. Typical bulk density of sandy soil is between 1. But dense rocks, such as granite, have tiny air pockets inside them, too. These pockets of air are just much smaller. If you picked up one volcanic rock as well as one granite rock of the same size, you would notice they don't weigh the same.

The granite is heavier than the volcanic rock. The many large holes of air in the latter make it less dense—and more porous—than the granite, which also makes it lighter. Something that has more holes in it is more porous. So "porosity" is one characteristic that can help tell you what kind of rock you have. Background Rocks—and most other objects, for that matter—are made up of particles of varying sizes that are packed together.

In between the particles are spaces that are filled with gas, air or liquid. Particles' shapes and sizes affect how they aggregate, including how tightly they can pack together, which affects a rock's porosity—a property that is the ratio of the volume of a rock's empty spaces to its total volume.

In general, larger particles cannot pack together as well as smaller particles can, which means that packing larger particles together leaves more space for air to fill between the particles.

particle size and porosity relationship

You can imagine this if you have one cup full of marbles and another cup full of sand. You'll be able to see many more spaces between the marbles than between the grains of sand. Materials Water Measuring cup Rocks that can be sorted into one of three size groups ideally all of the same type of rock, such as granite Screen optional Preparation Make sure that the rocks are sorted into three different groups by size.

The greater the difference in size between the rocks is, the easier it'll be to interpret your results. There should be enough of each group of rocks to completely fill a plastic cup. Procedure Fill each clear plastic cup to the top with one of the groups of rocks.

Porosity video final

How much space do you see between the rocks in the different cups? Fill the measuring cup with one cup of water. Pour the water into one of the cups of rocks, filling the cup to the top. How much water is left in the measuring cup? Subtracting the amount left in the measuring cup from one cup will tell you how much volume the air between the rocks took up.

How much volume did the air take up?