A bulldozer or dozer is a crawler equipped with a substantial metal plate used to push large quantities of soil, rubble, or other such material during construction or conversion work and equipped at the rear with a claw-like device to loosen densely compacted materials. Bulldozers can be found on a wide range of sites and quarries, military bases, heavy industry factories, engineering projects and farms; the term "bulldozer" refers only to a tractor fitted with a dozer blade. Bulldozers are large and powerful tracked heavy equipment; the tracks give them excellent ground holding capability and mobility through rough terrain. Wide tracks help distribute the bulldozer's weight over a large area, thus preventing it from sinking in sandy or muddy ground. Extra wide tracks are known as LGP tracks. Bulldozers have transmission systems designed to take advantage of the track system and provide excellent tractive force; because of these attributes, bulldozers are used in road building, mining, land clearing, infrastructure development, any other projects requiring mobile and stable earth-moving equipment.
Another type of bulldozer is the wheeled bulldozer, which has four wheels driven by a 4-wheel-drive system and has a hydraulic, articulated steering system. The blade is mounted forward of the articulation joint, is hydraulically actuated; the bulldozer's primary tools are the ripper. The word "bulldozer" is sometimes used inaccurately for other similar construction vehicles such as a large front loader; the bulldozer blade is a heavy metal plate on the front of the tractor, used to push objects, shove sand, soil and sometimes snow. Dozer blades come in three varieties: A straight blade, short and has no lateral curve and no side wings and can be used for fine grading. A universal blade, tall and curved, has large side wings to carry more material. An "S-U" combination blade, shorter, has less curvature, smaller side wings; this blade is used for pushing piles of large rocks, such as at a quarry. Blades can be fitted straight across the frame, or at an angle, sometimes using additional'tilt cylinders' to vary the angle while moving.
The bottom edge of the blade can be sharpened. Sometimes a bulldozer is used to push another piece of earth moving equipment known as a "scraper"; the towed Fresno Scraper, invented in 1883 by James Porteous, was the first design to enable this to be done economically, removing the soil from the cut and depositing it elsewhere on shallow ground. Many dozer blades have a reinforced center section with this purpose in mind, are called "bull blades". In military use, dozer blades are fixed on combat engineering vehicles and can optionally be fitted on other vehicles, such as artillery tractors such as the Type 73 or M8 Tractor. Dozer blades can be mounted on main battle tanks, where it can be used to clear antitank obstacles and dig improvised shelters. Combat applications for dozer blades include clearing battlefield obstacles and preparing fire positions; the ripper is the long claw-like device on the back of the bulldozer. Rippers can come in groups of two or more. A single shank is preferred for heavy ripping.
The ripper shank is fitted with a replaceable tungsten steel alloy tip, referred to as a'boot'. Ripping rock breaks the ground surface rock or pavement into small rubble easy to handle and transport, which can be removed so grading can take place. With agricultural ripping, a farmer breaks up rocky or hard earth, otherwise unploughable, in order to farm it. For example, much of the best land in the California wine country consists of old lava flows; the grower shatters the lava with heavy bulldozers so surface trees can be planted. Some bulldozers are equipped with a less common rear attachment referred to as a stumpbuster, a single spike that protrudes horizontally and can be raised to get it out of the way. A stumpbuster is used to split a tree stump. A bulldozer with a stumpbuster is used for landclearing operations, is equipped with a brush-rake blade. Bulldozers have been further modified over time to evolve into new machines which can work in ways that the original bulldozer cannot. One example is that loader tractors were created by removing the blade and substituting a large volume bucket and hydraulic arms which can raise and lower the bucket, thus making it useful for scooping up earth and loading it into trucks, these are known as a Drott, trackscavator or track loader.
Other modifications to the original bulldozer include making it smaller to let it operate in small work areas where movement is limited, such as in mining. Some lightweight form of bulldozer are used in snow removal and as a tool for preparing winter sports areas for ski and snowboard sports. A small light bulldozer is sometimes called a "calfdozer". In an angledozer the blade can be pushed forward at one end to make it easier to push material away to the side; the original earthmoving bulldozers are still irreplaceable as their tasks are concentrated in deforestation, ground levelling, road carving. Heavy bulldozers are employed to level the terrain to prepare it for construction; the construction, however, is done by small bulldozers and loader tractors. Bulldozers employed for combat engineering roles are fitted with arm
A tamp is a device used to compact or flatten an aggregate or another powdered or granular material to make it resistant to further compression or to increase its density. Small, handheld tampers are used to compress ground coffee into a puck to prepare espresso. Manual or powered tampers compact gravel before laying a concrete or brick patio or walkway so that the underlying gravel layer does not settle over time, or compress the fill in a utility trench as seen in the illustration. Self-propelled, mechanised ballast tamping machines, which compact the ballast underneath rail tracks. Preparing some firearms and artillery pieces for firing may involve tamping the charge, such as explosive material or a projectile, into the barrel. For example, muzzle loaders. A fireplace can be tamped with similar tool to compress the material being burned; this improves the heat/burning efficiency, by reducing the volume of burning material, exposed to airflow. This is confused with damping - which involves reducing the intensity of the burn by restricting the flue or by the use of any fire retarding material such as water.
Compactor Sand rammer
A road roller is a compactor type engineering vehicle used to compact soil, concrete, or asphalt in the construction of roads and foundations. Similar rollers are used at landfills or in agriculture. Road rollers are referred to as steamrollers, regardless of their method of propulsion; the first road rollers were horse-drawn, were just borrowed farm implements. Since the effectiveness of a roller depends to a large extent on its weight, self-powered vehicles replaced horse-drawn rollers from the mid-19th century; the first such vehicles were steam rollers. Single-cylinder steam rollers were used for base compaction and run with high engine revs with low gearing to promote bounce and vibration from the crankshaft through to the rolls in much the same way as a vibrating roller; the double cylinder or compound steam rollers became popular from around 1910 onwards and were used for the rolling of hot-laid surfaces due to their smoother running engines, but both cylinder types are capable of rolling the finished surface.
Steam rollers were dedicated to a task by their gearing as the slower engines were for base compaction whereas the higher geared models were referred to as'chip chasers' which followed behind the hot tar and chipping laying machines. Some road companies in the United States used steamrollers through the 1950s, in the UK, some remained in commercial service until the early 1970s; as internal combustion engine technology improved during the 20th century, kerosene-, gasoline-, diesel-powered rollers replaced their steam-powered counterparts. The first internal-combustion powered road rollers were similar to the steam rollers they replaced, they used similar mechanisms to transmit power from the engine to the wheels large, exposed spur gears. Some users did not like them in their infancy, as the engines of the era were difficult to start the kerosene-powered ones. All road rollers in commercial use now use diesel power. Road rollers feature in films, both as objects of violence and horror and of hilarity, for example Jojo's Bizarre Adventure and A Fish Called Wanda.
Road rollers use the weight of the vehicle to compress the surface being rolled or use mechanical advantage. Initial compaction of the substrate on a road project is done using a padfoot drum roller, which achieves higher compaction density due to the pads having less surface area. On large freeways a four-wheel compactor with padfoot drum and a blade, such as a Caterpillar 815/825 series machine, would be used due to its high weight and the powerful pushing force to spread bulk material. On regional roads a smaller single padfoot drum machine may be used; the next machine is a single smooth drum compactor that compacts the high spots down until the soil is smooth, this is done in combination with a motor grader to get a level surface. Sometimes at this stage a pneumatic tyre roller would be used; these rollers feature two rows of pneumatic tyres that overlap, the flexibility of the tyres provides a kneading action that seals the surface and with some vertical movement of the wheels, enables the roller to operate on uneven ground.
Once the soil base is flat the pad drum compactor is no longer used on the road surface. The next course would be compacted using a smooth single drum, smooth tandem roller or pneumatic tyre roller in combination with a grader, a water truck to achieve the desired flat surface with the right moisture content for optimum compaction. Once the road base is compacted, the smooth single drum compactor is no longer used on the road surface; the final wear course of asphalt concrete is laid using a paver and compacted using a tandem smooth drum roller, a three-point roller or a pneumatic tyre roller. Three point rollers on asphalt were common once and are still used, but tandem vibrating rollers are the usual choice now, with the pneumatic tyre roller's kneading action being the last roller to seal off the surface. Rollers are used in landfill compaction; such compactors have padfoot or "sheep's-foot" drums, do not achieve a smooth surface. The pads aid in compression, due to the smaller area contacting the ground.
The roller can be a simple drum with a handle, operated by one person, weighs 100 pounds, or as large as a ride-on road roller weighing 22 short tons and costing more than US$150,000. A landfill unit may weigh 59 short tons. Rammer Walk-behind plate compactor/light Trench roller Walk-behind roller/light Walk-behind roller/heavy Tandem drum Tandem drum Single drum roller Pneumatic-tyred Roller, a.k.a. rubber tyre or multi-wheel Combination roller Three point roller Single drum roller 4-wheel 3-point Tandem drum Tractor-mounted and tractor-powered Drawn rollers or towed rollers Impact compactor Drum rol
In geotechnical engineering, soil compaction is the process in which a stress applied to a soil causes densification as air is displaced from the pores between the soil grains. When stress is applied that causes densification due to water being displaced from between the soil grains consolidation, not compaction, has occurred. Compaction is the result of heavy machinery compressing the soil, but it can occur due to the passage of animal feet. In soil science and agronomy, soil compaction is a combination of both engineering compaction and consolidation, so may occur due to a lack of water in the soil, the applied stress being internal suction due to water evaporation as well as due to passage of animal feet. Affected soils become less able to absorb rainfall, thus increasing erosion. Plants have difficulty in compacted soil because the mineral grains are pressed together, leaving little space for air and water, which are essential for root growth. Burrowing animals find it a hostile environment, because the denser soil is more difficult to penetrate.
The ability of a soil to recover from this type of compaction depends on climate and fauna. Soils with high shrink-swell capacity, such as vertisols, recover from compaction where moisture conditions are variable, but clays which do not crack as they dry cannot recover from compaction on their own unless they host ground-dwelling animals such as earthworms — the Cecil soil series is an example. Soil compaction is a vital part of the construction process, it is used for support of structural entities such as building foundations, roadways and earth retaining structures to name a few. For a given soil type certain properties may deem it more or less desirable to perform adequately for a particular circumstance. In general, the preselected soil should have adequate strength, be incompressible so that future settlement is not significant, be stable against volume change as water content or other factors vary, be durable and safe against deterioration, possess proper permeability; when an area is to be filled or backfilled the soil is placed in layers called lifts.
The ability of the first fill layers to be properly compacted will depend on the condition of the natural material being covered. If unsuitable material is left in place and backfilled, it may compress over a long period under the weight of the earth fill, causing settlement cracks in the fill or in any structure supported by the fill. In order to determine if the natural soil will support the first fill layers, an area can be proofrolled. Proofrolling consists of utilizing a piece heavy construction equipment to roll across the fill site and watching for deflections to be revealed; these areas will be indicated by the development of pumping, or ground weaving. To ensure adequate soil compaction is achieved, project specifications will indicate the required soil density or degree of compaction that must be achieved; these specifications are recommended by a geotechnical engineer in a geotechnical engineering report. The soil type - that is, grain-size distributions, shape of the soil grains, specific gravity of soil solids, amount and type of clay minerals, present - has a great influence on the maximum dry unit weight and optimum moisture content.
It has a great influence on how the materials should be compacted in given situations. Compaction is accomplished by use of heavy equipment. In sands and gravels, the equipment vibrates, to cause re-orientation of the soil particles into a denser configuration. In silts and clays, a sheepsfoot roller is used, to create small zones of intense shearing, which drives air out of the soil. Determination of adequate compaction is done by determining the in-situ density of the soil and comparing it to the maximum density determined by a laboratory test; the most used laboratory test is called the Proctor compaction test and there are two different methods in obtaining the maximum density. They are modified Proctor tests. For small dams, the standard Proctor may still be the reference. While soil under structures and pavements needs to be compacted, it is important after construction to decompact areas to be landscaped so that vegetation can grow. There are several means of achieving compaction of a material.
Some are more appropriate for soil compaction than others, while some techniques are only suitable for particular soils or soils in particular conditions. Some are more suited to compaction of non-soil materials such as asphalt; those that can apply significant amounts of shear as well as compressive stress, are most effective. The available techniques can be classified as: Static - a large stress is applied to the soil and released. Impact - the stress is applied by dropping a large mass onto the surface of the soil. Vibrating - a stress is applied and via a mechanically driven plate or hammer. Combined with rolling compaction. Gyrating - a static stress is applied and maintained in one direction while the soil is a subjected to a gyratory motion about the axis of static loading. Limited to laboratory applications. Rolling - a heavy cylinder is rolled over the surface of the soil. Used on sports pitches. Roller-compactors are fitted with vibratory devices to enhance their effectiveness. Kneading - shear is applied by alternating movement in adjacent positions.
An example, combined with rolling compaction, is the'sheepsfoot' roller used in waste compaction at landfills. The construction plant available
A crusher is a machine designed to reduce large rocks into smaller rocks, gravel, or rock dust. Crushers may be used to reduce the size, or change the form, of waste materials so they can be more disposed of or recycled, or to reduce the size of a solid mix of raw materials, so that pieces of different composition can be differentiated. Crushing is the process of transferring a force amplified by mechanical advantage through a material made of molecules that bond together more and resist deformation more, than those in the material being crushed do. Crushing devices hold material between two parallel or tangent solid surfaces, apply sufficient force to bring the surfaces together to generate enough energy within the material being crushed so that its molecules separate from, or change alignment in relation to, each other; the earliest crushers were hand-held stones, where the weight of the stone provided a boost to muscle power, used against a stone anvil. Querns and mortars are types of these crushing devices.
In industry, crushers are machines which use a metal surface to break or compress materials into small fractional chunks or denser masses. Throughout most of industrial history, the greater part of crushing and mining part of the process occurred under muscle power as the application of force concentrated in the tip of the miners pick or sledge hammer driven drill bit. Before explosives came into widespread use in bulk mining in the mid-nineteenth century, most initial ore crushing and sizing was by hand and hammers at the mine or by water powered trip hammers in the small charcoal fired smithies and iron works typical of the Renaissance through the early-to-middle industrial revolution, it was only after explosives, early powerful steam shovels produced large chunks of materials, chunks reduced by hammering in the mine before being loaded into sacks for a trip to the surface, chunks that were also to lead to rails and mine railways transporting bulk aggregations that post-mine face crushing became necessary.
The earliest of these were in the foundries, but as coal took hold the larger operations became the coal breakers that fueled industrial growth from the first decade of the 1600s to the replacement of breakers in the 1970s through the fuel needs of the present day. The gradual coming of that era and displacement of the cottage industry based economies was itself accelerated first by the utility of wrought and cast iron as a desired materials giving impetus to larger operations in the late-sixteenth century by the increasing scarcity of wood lands for charcoal production to make the newfangled window glass material that had become—along with the chimney—'all the rage' among the growing middle-class and affluence of the sixteenth-and-seventeenth centuries. Other metallurgical developments such as silver and gold mining mirrored the practices and developments of the bulk material handling methods and technologies feeding the burgeoning appetite for more and more iron and glass, both of which were rare in personal possessions until the 1700s.
Things only became worse when the English figured out how to cast the more economical iron cannons, following on their feat of becoming the armorers of the European continent's powers by having been leading producers brass and bronze guns, by various acts of Parliament banned or restricted the further cutting of trees for charcoal in larger and larger regions in the United Kingdom. In 1611, a consortium led by courtier Edward Zouch was granted a patent for the reverberatory furnace, a furnace using coal, not precious national timber reserves, employed in glass making. An early politically connected and wealthy Robber Baron figure Sir Robert Mansell bought his way into the fledgling furnace company wrested control of it, by 1615 managed to have James I issued a proclamation forbidding the use of wood to produce glass, giving his families extensive coal holdings a monopoly on both source and means of production for nearly half-a-century. Abraham Darby a century relocated to Bristol where he had established a building brass and bronze industry by importing Dutch workers and using them to raid Dutch techniques.
Both materials were considered superior to iron for cannon, machines as they were better understood. But Darby would change the world in several key ways. Where the Dutch had failed in casting iron, one of Darby's apprentices, John Thomas succeeded in 1707 and as Burke put it: "had given England the key to the Industrial Revolution". At the time and foundries were all small enterprises except for the tin mines and materials came out of the mines hammered small by legions of miners who had to stuff their work into carry sacks for pack animal slinging. Concurrently, mines needed drained resulting in Savery and Newcomen's early steam driven pumping systems; the deeper the mines went, the larger the demand became for better pumps, the greater the demand for iron, the greater the need for coal, the greater the demand for each. Seeing ahead Darby, sold off his brass business interests and relocated to Coalbrookdale with its plentiful coal mines, water power and nearby ore supplies. Over that decade his foundries developed iron casting technologies and began to supplant other metals in many applications.
He adapted Coking of his fuel by copying Brewers practices. In 1822 the pumping industries needs for larger cylinders met up with Darby's ability to melt sufficient quantities of pig iron to cast large in
Waste are unwanted or unusable materials. Waste is any substance, discarded after primary use, or is worthless, defective and of no use. A by-product by contrast is a joint product of minor economic value. A waste product may become a by-product, joint product or resource through an invention that raises a waste product's value above zero. Examples include municipal solid waste, hazardous waste, radioactive waste, others. According to the Basel Convention on the Control of Transboundary Movements of Hazardous Wastes and Their Disposal of 1989, Art. 2, "'Wastes' are substance or objects, which are disposed of or are intended to be disposed of or are required to be disposed of by the provisions of national law". The UNSD Glossary of Environment Statistics describes waste as "materials that are not prime products for which the generator has no further use in terms of his/her own purposes of production, transformation or consumption, of which he/she wants to dispose. Wastes may be generated during the extraction of raw materials, the processing of raw materials into intermediate and final products, the consumption of final products, other human activities.
Residuals recycled or reused at the place of generation are excluded." Under the Waste Framework Directive 2008/98/EC, Art. 3, the European Union defines waste as "an object the holder discards, intends to discard or is required to discard." For a more structural description of the Waste Directive, see the European Commission's summary. There are many waste types defined by modern systems of waste management, notably including: Municipal waste includes household waste, commercial waste, demolition waste Hazardous waste includes industrial waste Biomedical waste includes clinical waste Special hazardous waste includes radioactive waste, explosive waste, electronic waste There are many issues that surround reporting waste, it is most measured by size or weight, there is a stark difference between the two. For example, organic waste is much heavier when it is wet, plastic or glass bottles can have different weights but be the same size. On a global scale it is difficult to report waste because countries have different definitions of waste and what falls into waste categories, as well as different ways of reporting.
Based on incomplete reports from its parties, the Basel Convention estimated 338 million tonnes of waste was generated in 2001. For the same year, OECD estimated 4 billion tonnes from its member countries. Despite these inconsistencies, waste reporting is still useful on a small and large scale to determine key causes and locations, to find ways of preventing, recovering and disposing waste. Inappropriately managed waste can attract rodents and insects, which can harbour gastrointestinal parasites, yellow fever, the plague and other conditions for humans, exposure to hazardous wastes when they are burned, can cause various other diseases including cancers. Toxic waste materials can contaminate surface water, groundwater and air which causes more problems for humans, other species, ecosystems. Waste treatment and disposal produces significant green house gas emissions, notably methane, which are contributing to global warming. Waste management is a significant environmental justice issue. Many of the environmental burdens cited above are more borne by marginalized groups, such as racial minorities and residents of developing nations.
NIMBY is the opposition of residents to a proposal for a new development because it is close to them. However, the need for expansion and siting of waste treatment and disposal facilities is increasing worldwide. There is now a growing market in the transboundary movement of waste, although most waste that flows between countries goes between developed nations, a significant amount of waste is moved from developed to developing nations; the economic costs of managing waste are high, are paid for by municipal governments. Environmental policies such as pay as you throw can reduce the cost of management and reduce waste quantities. Waste recovery can curb economic costs because it avoids extracting raw materials and cuts transportation costs. "Economic assessment of municipal waste management systems – case studies using a combination of life-cycle assessment and life-cycle costing". The location of waste treatment and disposal facilities reduces property values due to noise, pollution and negative stigma.
The informal waste sector consists of waste pickers who scavenge for metals, plastic and other materials and trade them for a profit. This sector can alter or reduce waste in a particular system, but other negative economic effects come with the disease, poverty and abuse of its workers. Resource recovery is the retrieval of recyclable waste, intended for disposal, for a specific next use, it is the processing of recyclables to extract or recover materials and resources, or convert to energy. This process is carried out at a resource recovery facility. Resource recovery is not only important to the environment, but it can be cost effective by decreasing the amount of waste sent to the disposal stream, reduce the amount of space needed for landfills, protect limited natural resources. Energy recovery from waste is using non-recyclable waste materials and extra