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Geomembranes
A geomembrane is very low permeability (earth sciences), permeability synthetic membrane liner or barrier used with any geotechnical engineering related material so as to control fluid (liquid or gas) migration in a human-made project, structure, or system. Geomembranes are made from relatively thin continuous polymeric sheets, but they can also be made from the impregnation of geotextiles with Bitumen, asphalt, elastomer or polymer, polymer sprays, or as Bituminous Geomembranes (BGMs), multilayered bitumen geocomposites. Continuous polymer sheet geomembranes are, by far, the most common. Manufacturing The manufacturing of geomembranes begins with the production of the raw materials, which include the polymer resin, and various additives such as antioxidants, plasticizers, fillers, carbon black, and lubricants (as a processing aid). These raw materials (i.e., the "formulation") are then processed into sheets of various widths and thickness by extrusion, calendering, and/or spread ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Landfill Liner
A landfill liner, or composite liner, is intended to be a low permeable barrier, which is laid down under engineered landfill sites. Until it deteriorates, the liner retards migration of leachate, and its toxic constituents, into underlying aquifers or nearby rivers from causing potentially irreversible contamination of the local waterway and its sediments. Modern landfills generally require a layer of compacted clay with a minimum required thickness and a maximum allowable hydraulic conductivity, overlaid by a high-density polyethylene geomembrane. The United States Environmental Protection Agency has stated that the barriers "will ultimately fail," while sites remain threats for "thousands of years," suggesting that modern landfill designs delay but do not prevent ground and surface water pollution. Chipped or waste tires are used to support and insulate the liner. Types Different types of liquid trash will vary in their chemical properties and threat posed to the local env ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Bituminous Geomembranes (BGMs)
Bituminous geomembrane (BGM) is a type of geomembrane consisting of a reinforcing geotextile to provide mechanical strength and elastomeric bitumen (often called asphalt in American English, U.S.) to provide impermeability. Other components such as sand, a glass fleece, and/or a polyester film can be incorporated into the layers of a BGM. Bituminous geomembranes are differentiated from bituminous waterproofing materials used in buildings due in part to their wide roll width, which can exceed 5m, and their substantial thickness of up to 6.0mm. These properties are designed for environmental protection, civil infrastructure, and mining applications. Properties History The earliest estimated use of bitumen dates back 40,000 years to the Paleolithic age and bitumen#History, the historical use of bitumen as a waterproofing layer is extensive and well documented. In 1926, successful experiments were conducted by the South Carolina Highway Department in which cotton fabric wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geosynthetics
Geosynthetics are synthetic products used to stabilize terrain. They are generally polymeric products used to solve civil engineering problems. This includes eight main product categories: geotextiles, geogrids, geonets, geomembranes, geosynthetic clay liners, geofoam, geocells and geocomposites. The polymeric nature of the products makes them suitable for use in the ground where high levels of durability are required. They can also be used in exposed applications. Geosynthetics are available in a wide range of forms and materials. These products have a wide range of applications and are currently used in many civil, geotechnical, transportation, geoenvironmental, hydraulic, and private development applications including roads, airfields, railroads, embankments, retaining structures, reservoirs, canals, dams, erosion control, sediment control, landfill liners, landfill covers, mining, aquaculture and agriculture. History Inclusions of different sorts mixed with soil ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Linear Low-density Polyethylene
Linear low-density polyethylene (LLDPE) is a substantially linear polymer (polyethylene), with significant numbers of short branches, commonly made by copolymerization of ethylene with longer-chain olefins. Linear low-density polyethylene differs structurally from conventional low-density polyethylene (LDPE) because of the absence of long chain branching. The linearity of LLDPE results from the different manufacturing processes of LLDPE and LDPE. In general, LLDPE is produced at lower temperatures and pressures by copolymerization of ethylene and such higher alpha-olefins as butene, hexene, or octene. The amount of comonomer is typically in the range from 1 to 10%. The copolymerization process produces an LLDPE polymer that has a narrower molecular weight distribution than conventional LDPE and in combination with the linear structure, significantly different rheological properties. Production and properties The production of LLDPE is initiated by transition metal catalyst ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fly Ash
Coal combustion products (CCPs), also called coal combustion wastes (CCWs) or coal combustion residuals (CCRs), are byproducts of burning coal. They are categorized in four groups, each based on physical and chemical forms derived from coal combustion methods and emission controls: * Fly ash is captured after coal combustion by filters (Dust collector#Fabric filters, bag houses), electrostatic precipitators and other air pollution control devices. It comprises 60 percent of all coal combustion waste (labeled here as coal combustion products). It is most commonly used as a high-performance substitute for Portland cement or as Cement clinker, clinker for Portland cement production. Cements blended with fly ash are becoming more common. Building material applications range from grouts and masonry products to cellular concrete and roofing tiles. Many asphaltic concrete pavements contain fly ash. Geotechnical applications include soil stabilization, road base, structural fill, embankmen ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Geotechnical Engineering
Geotechnical engineering, also known as geotechnics, is the branch of civil engineering concerned with the engineering behavior of earth materials. It uses the principles of soil mechanics and rock mechanics to solve its engineering problems. It also relies on knowledge of geology, hydrology, geophysics, and other related sciences. Geotechnical engineering has applications in military engineering, mining engineering, petroleum engineering, coastal engineering, and offshore construction. The fields of geotechnical engineering and engineering geology have overlapping knowledge areas. However, while geotechnical engineering is a specialty of civil engineering, engineering geology is a specialty of geology. History Humans have historically used soil as a material for flood control, irrigation purposes, burial sites, building foundations, and construction materials for buildings. Dykes, dams, and canals dating back to at least 2000 BCE—found in parts of ancient Egypt, ancient Mes ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Density
Density (volumetric mass density or specific mass) is the ratio of a substance's mass to its volume. The symbol most often used for density is ''ρ'' (the lower case Greek letter rho), although the Latin letter ''D'' (or ''d'') can also be used: \rho = \frac, where ''ρ'' is the density, ''m'' is the mass, and ''V'' is the volume. In some cases (for instance, in the United States oil and gas industry), density is loosely defined as its weight per unit volume, although this is scientifically inaccurate this quantity is more specifically called specific weight. For a pure substance, the density is equal to its mass concentration. Different materials usually have different densities, and density may be relevant to buoyancy, purity and packaging. Osmium is the densest known element at standard conditions for temperature and pressure. To simplify comparisons of density across different systems of units, it is sometimes replaced by the dimensionless quantity "relative den ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Various Methods Available To Fabricate Geomembrane Seams
Various may refer to: * Various (band), an English dubstep/electronic music duo * Various artists, a term for a compilation album containing pieces by various musicians * Various authors, a book containing works by several writers * ''The Various'', a children's fantasy novel by Steve Augarde See also * Various & Gould, a Berlin-based artist duo * '' Various Artists – Archives Vol. 4'', an album by Steve Vai * ''Various Failures'', a compilation album by American experimental rock band Swans * ''The Various Haunts of Men'', a novel by Susan Hill * ''Various Positions'', an album by Leonard Cohen ** Various Positions Tour * ''Various Positions'' (film), a 2002 film directed by Ori Kowarsky * Varius (other) Varius (Latin language, Latin for "knock-kneed" and "different") may refer to: * Members of the gens (Roman), gens Varia, including ** Lucius Varius Rufus ( – 14 BC), Roman poet ** Lucius Varius Ambibulus (fl. ), Roman politician ** Sextus Variu ... * [Baidu] |
Tensile Strength
Ultimate tensile strength (also called UTS, tensile strength, TS, ultimate strength or F_\text in notation) is the maximum stress that a material can withstand while being stretched or pulled before breaking. In brittle materials, the ultimate tensile strength is close to the yield point, whereas in ductile materials, the ultimate tensile strength can be higher. The ultimate tensile strength is usually found by performing a tensile test and recording the engineering stress versus strain. The highest point of the stress–strain curve is the ultimate tensile strength and has units of stress. The equivalent point for the case of compression, instead of tension, is called the compressive strength. Tensile strengths are rarely of any consequence in the design of ductile members, but they are important with brittle members. They are tabulated for common materials such as alloys, composite materials, ceramics, plastics, and wood. Definition The ultimate tensile strength ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Accelerated Life Testing
Accelerated life testing is the process of testing a product by subjecting it to conditions ( stress, strain, temperatures, voltage, vibration rate, pressure etc.) in excess of its normal service parameters in an effort to uncover faults and potential modes of failure in a short amount of time. By analyzing the product's response to such tests, engineers can make predictions about the service life and maintenance intervals of a product. In polymers, testing may be done at elevated temperatures to produce a result in a shorter amount of time than it could be produced at ambient temperatures. Many mechanical properties of polymers have an Arrhenius type relationship with respect to time and temperature (for example, creep, stress relaxation, and tensile properties). If one conducts short tests at elevated temperatures, that data can be used to extrapolate the behavior of the polymer at room temperature, avoiding the need to do lengthy, and hence expensive tests. Purpose ALT is p ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Modulus Of Elasticity
An elastic modulus (also known as modulus of elasticity (MOE)) is a quantity that describes an object's or substance's resistance to being deformed elastically (i.e., non-permanently) when a stress is applied to it. Definition The elastic modulus of an object is defined as the slope of its stress–strain curve in the elastic deformation region: A stiffer material will have a higher elastic modulus. An elastic modulus has the form: :\delta \ \stackrel\ \frac where stress is the force causing the deformation divided by the area to which the force is applied and strain is the ratio of the change in some parameter caused by the deformation to the original value of the parameter. Since strain is a dimensionless quantity, the units of \delta will be the same as the units of stress. Elastic constants and moduli Elastic constants are specific parameters that quantify the stiffness of a material in response to applied stresses and are fundamental in defining the elastic pro ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
