Porosity is a measure of the void spaces in a material, and is measured as a fraction, between 0–1, or as a percentage between 0–100%. The term porosity is used in multiple fields including manufacturing, earth sciences and construction. The percent sign. ...

Porosity in earth sciences and construction

Used in geology, hydrogeology, soil science, and building science, the porosity of a porous medium (such as rock or sediment) describes the fraction of void space in the material, where the void may contain, for example, air or water. It is defined by the ratio: This article includes a list of works cited but its sources remain unclear because it lacks in-text citations. ... Hydrogeology (hydro- meaning water, and -geology meaning the study of the Earth) is the part of hydrology that deals with the distribution and movement of groundwater in the soil and rocks of the Earths crust, (commonly in aquifers). ... Soil science deals with soil as a natural resource on the surface of the earth including soil formation, classification and mapping; physical, chemical, biological, and fertility properties of soils per se; and these properties in relation to the use and management of soils. ... Building science is the collection of scientific knowledge that focuses on the analysis and control of the physical phenomena affecting the performance of building materials and building enclosure systems. ... A porous medium or a porous material is a solid (often called frame or matrix) permeated by an interconnected network of pores (voids) filled with a fluid (liquid or gas). ... This balancing rock, Steamboat Rock stands in Garden of the Gods park in Colorado Springs, CO The rocky side of a mountain creek near Orosí, Costa Rica. ... This article or section cites very few or no references or sources. ... A ratio is a quantity that denotes the proportional amount or magnitude of one quantity relative to another. ...

where V_V is the volume of void-space (such as fluids) and V_T is the total or bulk volume of material, including the solid and void components. Both the mathematical symbols φ and n are used to denote porosity.

Porosity is a fraction between 0 and 1, typically ranging from less than 0.01 for solid granite to more than 0.5 for peat and clay, although it may also be represented in percent terms by multiplying the fraction by 100. Close-up of granite from Yosemite National Park, valley of the Merced River Quarrying granite for the Mormon Temple, Utah Territory. ... Peat in Lewis, Scotland Peat is an accumulation of partially decayed vegetation matter. ... The Gay Head cliffs in Marthas Vineyard are made almost entirely of clay. ...

The porosity of a rock, or sedimentary layer, is an important consideration when attempting to evaluate the potential volume of water or hydrocarbons it may contain. Sedimentary porosities are a complex function of many factors, including but not limited to: rate of burial, depth of burial, the nature of the connate fluids, the nature of overlying sediments (which may impede fluid expulsion). One commonly used relationship between porosity and depth is given by the Athy (1930) equation: Impact from a water drop causes an upward rebound jet surrounded by circular capillary waves. ... Oil refineries are key to obtaining hydrocarbons; crude oil is processed through several stages to form desirable hydrocarbons, used in fuel and other commercial products. ...

where φ₀ is the surface porosity, k is the compaction coefficient (m⁻¹) and z is depth (m).

A value for porosity can alternatively be calculated from the bulk density and particle density: Bulk density a property of particulate materials. ... The particle density or true density of a particulate solid or powder, is the density of the particles that make up the powder, in contrast to the bulk density, which measures the average density of a large volume of the powder in a specific medium (usually air). ...

Normal particle density is assumed to be approximately 2.65 g/cm³, although a better estimation can be obtained by examining the lithology of the particles. Petrology is a field of geology which focuses on the study of rocks and the conditions by which they form. ...

Porosity and hydraulic conductivity

Porosity is indirectly related 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 water), but there are many complications to this relationship. Clays, which typically have very low hydraulic conductivity also have very high porosities (due to the structured nature of clay minerals), which means clays can hold a large volume of water per volume of bulk material, but they do not release water very quickly. written by AmerHydraulic conductivity, mathematically represented as , is a property of soil or rock, in the vadose zone or groundwater, that describes the ease with which water can move through pore spaces or fractures. ... Patterns in the sand Sand is a granular material made up of fine rock particles. ... Clay minerals are hydrous aluminium silicates, sometimes with minor amounts of iron, magnesium and other cations. ...

Sorting and porosity

Effects of sorting on alluvial porosity

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 place), drastically 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 materials, see the "further reading" section in the Hydrogeology article. Image File history File links This is a lossless scalable vector image. ... Image File history File links This is a lossless scalable vector image. ... Particle size, also called grain size, refers to the diameter of individual grains of sediment, or the lithified particles in clastic rocks. ... Hydrogeology (hydro- meaning water, and -geology meaning the study of the Earth) is the part of hydrology that deals with the distribution and movement of groundwater in the soil and rocks of the Earths crust, (commonly in aquifers). ...

Porosity of rocks

Consolidated rocks (e.g. sandstone, shale, granite or limestone) potentially have more complex "dual" porosities, as compared with alluvial sediment. The rock itself may have a certain (low) porosity, and the fractures (cracks and joints), or dissolution features may create a second (higher) porosity. The interaction of these porosities is complex and often makes simple models highly inaccurate. Red sandstone interior of Lower Antelope Canyon, Arizona, worn smooth due to erosion by flash flooding over millions of years Sandstone is a sedimentary rock composed mainly of sand-size mineral or rock grains. ... Shale Shale is a fine-grained sedimentary rock whose original constituents were clays or muds. ... Close-up of granite from Yosemite National Park, valley of the Merced River Quarrying granite for the Mormon Temple, Utah Territory. ... -1...

Porosity of soil

Porosity of surface soil typically decreases as particle size increases. 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 1.5 and 1.7 g/cm³. This calculates to a porosity between 0.43 and 0.36. Typical bulk density of clay soil is between 1.1 and 1.3 g/cm³. This calculates to a porosity between 0.58 and 0.51. This seems counterintuitive because clay soils are termed heavy, implying lower porosity. Heavy apparently refers to a gravitational moisture content effect in combination with terminology that harkens back to the relative force required to pull a tillage implement through the clayey soil at field moisture content as compared to sand. Soil life is a collective term for all the organisms living within the soil. ... To meet Wikipedias quality standards, this article or section may require cleanup. ...

Porosity of subsurface soil is lower than in surface soil due to compaction by gravity. Porosity of 0.20 is considered normal for unsorted gravel size material at depths below the biomantle. Porosity in finer material below the aggregating influence of pedogenesis can be expected to approximate this value. In oceanography and limnology, the displacement and mixing of sediment particles by benthic fauna (animals) or flora (plants) is termed bioturbation. ... Pedogenesis or soil evolution (formation) is the process by which soil is created. ...

Soil porosity is complex. Traditional models regard porosity as continuous. This fails to account for anomalous features and produces only approximate results. Furthermore it cannot help model the influence of environmental factors which affect pore geometry. A number of more complex models have been proposed, including fractals, bubble theory, cracking theory, Boolean grain process, packed sphere, and numerous other models. The boundary of the Mandelbrot set is a famous example of a fractal. ... Soap bubbles Bubble may refer to: Soap bubble, spherical liquid film, also possibly of bubble gum Cavitation, pocket of air caught in a liquid Bubble (economics), where speculation causes prices to rise to unsustainable levels a (normally) transparent dome Light bulb, in theater lighting terminology [1] in poker tournaments, the... Cracking-divides a group’s voters into other districts, where they will be ineffective minorities; and kidnapping places two incumbents from the same party in the same district. ... The adjective Boolean [], coined in honour of George Boole, is used in many contexts: An evaluation that results in either of the truth values true or false. A Boolean value is a truth value, either true or false, often coded 1 and 0, respectively. ...

Types of geologic porosities

• Primary porosity is the main or original porosity system in a rock or unconfined alluvial deposit.
• Secondary porosity is a subsequent or separate porosity system in a rock, often enhancing overall porosity of a rock. This can be a result of chemical leeching of minerals or the generation of a fracture system. This can replace the primary porosity or coexist with it (see dual porosity below).
• Fracture porosity is porosity associated with a fracture system or faulting. This can create secondary porosity in rocks that otherwise would not be reservoirs for hydrocarbons due to their primary porosity being destroyed (for example due to depth of burial) or of a rock type not normally considered a reservoir (for example igneous intrusions or metasediments).
• Vuggy porosity is secondary porosity generated by dissolution of large features (such as macrofossils) in carbonate rocks leaving large holes, vugs, or even caves.
• Effective porosity (also called open porosity) refers to the fraction of the total volume in which fluid flow is effectively taking place (this excludes dead-end pores or non-connected cavities). This is very important for groundwater and petroleum flow, as well as for solute transport.
• Dual porosity refers to the conceptual idea that there are two overlapping reservoirs which interact. In fractured rock aquifers, the rock mass and fractures are often simulated as being two overlapping but distinct bodies. Delayed yield, and leaky aquifer flow solutions are both mathematically similar solutions to that obtained for dual porosity; in all three cases water comes from two mathematically different reservoirs (whether or not they are physically different).
• Macro porosity refers to pores greater than 50 nm in diameter. Flow through macropores is described by bulk diffusion.
• Meso porosity refers to pores greater than 2 nm and less than 50 nm in diameter. Flow through mesopores is described by knudsen diffusion.
• Micro porosity refers to pores smaller than 2 nm in diameter. Movement in micropores is by activiated diffusion.

This balancing rock, Steamboat Rock stands in Garden of the Gods park in Colorado Springs, CO The rocky side of a mountain creek near Orosí, Costa Rica. ... Alluvium (from the Latin, alluvius, from alluere, to wash against) is soil or sediments deposited by a river or other running water. ... In the lower left, a spherule, or sphere-shaped grain, can be seen penetrating the interior of a small cavity called a vug. ... Lechuguilla Cave, New Mexico A cave is a natural underground void large enough for a human to enter. ... NM may stand for: National Master, a chess title Nautical mile, a unit of length used for maritime and aviation purposes Neal Morse, an American multi-instrumentalist Network marketing, a business model that combines direct marketing with franchising Neurofiber mitosis, a nerve disease, sometimes confused with neurofibromatosis New Mexico, in...

Porosity in manufacturing

In manufacturing of metal or plastic parts and assemblies, porosity in the raw material is a serious issue affecting the quality of the resulting products. Porosity may be caused by temperature control problems, material impurities, or other causes in the casting of metal or plastic parts. Porosity internal to cast parts may become external or surface pores when material is then removed from the raw part material by machining, grinding or other manufacturing operations. Surface pores, if not detected, may cause leakage to occur between the mating surfaces of parts comprising an assembly or between cavities in an assembly in which substantial pressure differentials are desired. An example is the required pressure differential between the cylinders of an engine or between the region above and below a piston or a valve in a cylinder. The ultimate result of undetected and uncorrected porosity can include loss of performance, leakage of lubricants or fuel, and contamination of various portions of the assembled mechanism or product. Detection of surface porosity requires the use of some form of 3-dimensional high-definition metrology, because pores of concern may be as small as 100 micrometres in diameter (roughly the diameter of an average human hair) and may occur anywhere on the surface of a part. Pores in machined metal or plastic vary significantly in shape, depth, size and the surface characteristics (such as surface roughness ) within the perimeter of the pore. If pores are not detected prior to assembly of mating surfaces during the manufacturing process, then considerable additional manufacturing cost is usually incurred as the resulting assembly has to be disassembled or scrapped after pressure testing or other later performance tests reveal deficiencies. Manufacturing (from Latin manu factura, making by hand) is the use of tools and labor to make things for use or sale. ... A micrometre (American spelling: micrometer), symbol µm, is an SI unit of length. ... It has been suggested that Rugosity be merged into this article or section. ...

Measuring porosity

There are several ways to estimate the porosity of a given material or mixture of materials, which is called your material matrix. Image File history File links Information. ... Wikibooks logo Wikibooks, previously called Wikimedia Free Textbook Project and Wikimedia-Textbooks, is a wiki for the creation of books. ... Image File history File links Information. ... Grammatical person, in linguistics, is deictic reference to the participant role of a referent, such as the speaker, the addressee, and others. ... This Manual of Style has the simple purpose of making things easy to read by following a consistent format — it is a style guide. ...

• The volume/density method is fast and surprisingly accurate (normally within 2 % of the actual porosity). To do this method you pour your material into a beaker, cylinder or some other container of a known volume. Weigh your container so you know its empty weight, then pour your material into the container. Tap the side of the container until it has finished settling and measure the volume in the container. Then weigh your container full of this material, so you can subtract the weight of the container to know just the weight of just your material. So now you have both the volume and the weight of the material. The weight of your material divided by the density of your material gives you the volume that your material takes up, minus the pore volume. (The assumed density of most rocks, sand, glass, etc. is assumed to be 2.65 g/cm³. If you have a different material, you may look up its density) So, the pore volume is simply equal to the total volume minus the material volume, or more directly (pore volume) = (total volume) - (material volume).

• Water saturation method is slightly harder to do, but is more accurate and more direct. Again, take a known volume of your material and also a known volume of water. (Make sure the beaker or container is large enough to hold your material as well.) Slowly dump your material into the water and let it saturate as you pour it in. Then seal the beaker (with a piece of parafilm tape or if you don't have parafilm tape a plastic bag tied around the beaker will do.) and let it sit for a few hours to insure the material is fully saturated. Then remove the unsaturated water from the top of the beaker and measure its volume. The total volume of the water originally in the beaker minus the amount of water not saturated is the volume of the pore space, or again more directly (pore volume) = (total volume of water) - (unsaturated water).

• Water evaporation method is the hardest to do, but is also the most accurate. Take a fully saturated, known volume of your material with no excess water on top. Weigh your container with the material and water and then place your container into a heater to dry it out. Drying out your sample may take several days depending on the heat applied and the volume of your sample. Then weigh your dried sample. Since the density of water is 1 g/cm³, the difference of the weights of the saturated versus the dried sample is equal to the volume of the water removed from the sample (assuming you are measuring in grams), which is exactly the pore volume. So once again, (pore volume in cubic centimeters) = (weight of saturated sample in grams) - (weight of dried sample in grams).

• Mercury intrusion porosimetry requires the sample to be placed special filling device that allows the sample to be evacuated followed by the introduction of liquid mercury. The size of the mercury envelope is then measured as a function of increased applied pressure. The greater the applied pressure, the smaller the pore entered by mercury. Typically this method is used over the range of pores from 300 µm to 0.0035 µm. This method is used to characterize a variety of porous material from coal to fabrics. Because of increased concern over use of mercury, several non-mercury intrusion techniques have been developed.

• Nitrogen gas adsorption is used to determine fine porosity in materials such as charcoal. In very small pores, nitrogen gas condenses on the pore walls less than 0.090 µm. This condensation is measured either by volume or weight.

The volume of a solid object is the three-dimensional concept of how much space it occupies, often quantified numerically. ... A spring scale measures the weight of an object In the physical sciences, weight is a measurement of the gravitational force acting on an object. ... In physics, density is mass m per unit volume V. For the common case of a homogeneous substance, it is expressed as: where, in SI units: ρ (rho) is the density of the substance, measured in kg·m-3 m is the mass of the substance, measured in kg V is... Perhaps one of the most ubiquitous of laboratory items, Parafilm is a product of the American Can Company, consisting of a flexible film, available in several different lengths and widths, that is commonly used for sealing or protecting vessels. ... In chemistry, saturation has four different meanings: In physical chemistry, saturation is the point at which a solution of a substance can dissolve no more of that substance and additional amounts of that substance will appear as a precipitate. ...

See also

• Petroleum geology
• Poromechanics
• Bulk density
• Particle density

Petroleum geology is a term used to refer to the specific set of geological disciplines that are applied to the search for hydrocarbons (oil exploration). ... Poromechanics is a branch of physics and specifically continuum mechanics and acoustics that studies the behaviour of fluid-saturated porous media. ... Bulk density a property of particulate materials. ... The particle density or true density of a particulate solid or powder, is the density of the particles that make up the powder, in contrast to the bulk density, which measures the average density of a large volume of the powder in a specific medium (usually air). ...

References

Horgan, Graham W. October 1, 1996 A review of soil pore models Posted by author. url (pdf) accessed on 2006-04-16 Year 2006 (MMVI) was a common year starting on Sunday (link displays full 2006 calendar) of the Gregorian calendar. ... is the 106th day of the year (107th in leap years) in the Gregorian calendar. ...

Nelson, J. Roy, January 2000 Physics of Impregnation Microscopy Today, issue #00-1, Posted by author.