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103-403: In the construction industry, mud is a semi-fluid material that can be used to coat, seal, or adhere materials. The term "mud" can be used for various semi-fluid materials used in construction including slurry , mortar , plaster , stucco , and concrete . Mud, cob , adobe , clay , and many other names are historically used synonymously to mean a mixture of subsoil and water possibly with

206-476: A designer , a contractor , a construction manager , or other advisors); such specialists are normally appointed for their expertise in project delivery and construction management and will help the owner define the project brief , agree on a budget and schedule , liaise with relevant public authorities, and procure materials and the services of other specialists (the supply chain , comprising subcontractors and materials suppliers). Contracts are agreed for

309-408: A meter or more downwards. This means that the burrowed mud is a productive habitat , providing food and shelter for a wide range of mud-dwellers and other animals that forage in and over the mud. Mud can pose problems for motor traffic when moisture is present, because every vehicle function that changes direction or speed relies on friction between the tires and the road surface, so

412-422: A "live" environment (where residents or businesses remain living in or operating on the site) requires particular care, planning and communication. When applicable, a proposed construction project must comply with local land-use planning policies including zoning and building code requirements. A project will normally be assessed (by the 'authority having jurisdiction', AHJ, typically the municipality where

515-445: A building or other asset that affect safety, including its use, expansion, structural integrity, and fire protection , usually require municipality approval. Depending on the type of project, mortgage bankers , accountants , and cost engineers may participate in creating an overall plan for the financial management of a construction project. The presence of the mortgage banker is highly likely, even in relatively small projects since

618-640: A business to lead both design and construction ( design-build ); or they may directly appoint a designer, contractor and specialist subcontractors ( construction management ). Some forms of procurement emphasize collaborative relationships ( partnering , alliancing) between the client, the contractor, and other stakeholders within a construction project, seeking to ameliorate often highly competitive and adversarial industry practices. DfMA (design for manufacture and assembly) approaches also emphasize early collaboration with manufacturers and suppliers regarding products and components. Construction or refurbishment work in

721-423: A change in pressure at one point in a liquid is transmitted undiminished to every other part of the liquid and very little energy is lost in the form of compression. However, the negligible compressibility does lead to other phenomena. The banging of pipes, called water hammer , occurs when a valve is suddenly closed, creating a huge pressure-spike at the valve that travels backward through the system at just under

824-479: A conceptual cost estimate performed by a building estimator . As portions of a project are completed, they may be sold, supplanting one lender or owner for another, while the logistical requirements of having the right trades and materials available for each stage of the building construction project carry forward. Public–private partnerships (PPPs) or private finance initiatives (PFIs) may also be used to help deliver major projects. According to McKinsey in 2019,

927-423: A container. Although liquid water is abundant on Earth, this state of matter is actually the least common in the known universe, because liquids require a relatively narrow temperature/pressure range to exist. Most known matter in the universe is either gas (as interstellar clouds ) or plasma (as stars ). Liquid is one of the four primary states of matter , with the others being solid, gas and plasma . A liquid

1030-422: A fairly constant temperature, making a liquid suitable for blanching , boiling , or frying . Even higher rates of heat transfer can be achieved by condensing a gas into a liquid. At the liquid's boiling point, all of the heat energy is used to cause the phase change from a liquid to a gas, without an accompanying increase in temperature, and is stored as chemical potential energy . When the gas condenses back into

1133-459: A gas. Therefore, liquid and solid are both termed condensed matter . On the other hand, as liquids and gases share the ability to flow, they are both called fluids. A liquid is made up of tiny vibrating particles of matter, such as atoms, held together by intermolecular bonds . Like a gas, a liquid is able to flow and take the shape of a container. Unlike a gas, a liquid maintains a fairly constant density and does not disperse to fill every space of

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1236-403: A given rate, such as when it is being sheared at finite velocity. A specific example is a liquid flowing through a pipe: in this case the liquid undergoes shear deformation since it flows more slowly near the walls of the pipe than near the center. As a result, it exhibits viscous resistance to flow. In order to maintain flow, an external force must be applied, such as a pressure difference between

1339-490: A layer of mud on the surface of the road or tires can cause the vehicle to hydroplane . People and cars can also become stuck in mud, as in quicksand . Heavy rainfall , snowmelt , or high levels of groundwater may trigger a movement of soil or sediments , possibly causing mudslides , landslides , avalanches , or sinkholes . Mudslides in volcanic terrain (called lahars ) occur after eruptions as rain remobilizes loose ash deposits. Mudslides are also common in

1442-404: A limited degree of particle mobility. As the temperature increases, the increased vibrations of the molecules causes distances between the molecules to increase. When a liquid reaches its boiling point , the cohesive forces that bind the molecules closely together break, and the liquid changes to its gaseous state (unless superheating occurs). If the temperature is decreased, the distances between

1545-433: A liquid this excess heat-energy is released at a constant temperature. This phenomenon is used in processes such as steaming . Since liquids often have different boiling points, mixtures or solutions of liquids or gases can typically be separated by distillation , using heat, cold, vacuum , pressure, or other means. Distillation can be found in everything from the production of alcoholic beverages , to oil refineries , to

1648-451: A mixture of otherwise immiscible liquids can be stabilized to form an emulsion , where one liquid is dispersed throughout the other as microscopic droplets. Usually this requires the presence of a surfactant in order to stabilize the droplets. A familiar example of an emulsion is mayonnaise , which consists of a mixture of water and oil that is stabilized by lecithin , a substance found in egg yolks . The microscopic structure of liquids

1751-419: A required shape and heating them to high temperatures in a kiln which removes all the water from the clay , which induces reactions that lead to permanent changes including increasing their strength and hardening and setting their shape. A clay body can be decorated before or after firing. Prior to some shaping processes, clay must be prepared. Kneading helps to ensure an even moisture content throughout

1854-482: A rotating liquid forms a circular paraboloid and can therefore be used as a telescope . These are known as liquid-mirror telescopes . They are significantly cheaper than conventional telescopes, but can only point straight upward ( zenith telescope ). A common choice for the liquid is mercury. Quantities of liquids are measured in units of volume . These include the SI unit cubic metre (m ) and its divisions, in particular

1957-433: A rule is inapplicable (the bridge design will not cause a collapse), or that the custom is no longer needed (acceptance of live-work spaces has grown in the community). During the construction of a building, a municipal building inspector usually inspects the ongoing work periodically to ensure that construction adheres to the approved plans and the local building code. Once construction is complete, any later changes made to

2060-512: A well-drained flat roof may be protected with a well-prepared ( puddled ) and properly maintained dried mud coating, viable as the mud will expand when moistened and so become more water resistant. Adobe mudbricks were commonly used by the Pueblo Indians to build their homes and other necessary structures. In some countries there are entire cities made of mud brick houses. Cow dung and biomass are added to regulate indoor climate. Mud that

2163-446: Is a fluid . Unlike a solid, the molecules in a liquid have a much greater freedom to move. The forces that bind the molecules together in a solid are only temporary in a liquid, allowing a liquid to flow while a solid remains rigid. A liquid, like a gas, displays the properties of a fluid. A liquid can flow, assume the shape of a container, and, if placed in a sealed container, will distribute applied pressure evenly to every surface in

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2266-472: Is a fixed amount of energy associated with forming a surface of a given area. This quantity is a material property called the surface tension , in units of energy per unit area (SI units: J / m ). Liquids with strong intermolecular forces tend to have large surface tensions. A practical implication of surface tension is that liquids tend to minimize their surface area, forming spherical drops and bubbles unless other constraints are present. Surface tension

2369-403: Is a nearly incompressible fluid that conforms to the shape of its container but retains a nearly constant volume independent of pressure. It is one of the four fundamental states of matter (the others being solid , gas , and plasma ), and is the only state with a definite volume but no fixed shape. The density of a liquid is usually close to that of a solid, and much higher than that of

2472-407: Is a stage in the process of refinement of the materials , since larger particles will settle from the liquid . Mud can provide a home for numerous types of animals, including varieties of worms , frogs , snails , clams , and crayfish . Other animals, such as hippopotamuses , pigs , rhinoceroses , water buffalo and elephants , bathe in mud in order to cool off and protect themselves from

2575-440: Is complex and historically has been the subject of intense research and debate. A few of the key ideas are explained below. Microscopically, liquids consist of a dense, disordered packing of molecules. This contrasts with the other two common phases of matter, gases and solids. Although gases are disordered, the molecules are well-separated in space and interact primarily through molecule-molecule collisions. Conversely, although

2678-436: Is considered to be a promising candidate for these applications as it is a liquid near room temperature, has low toxicity, and evaporates slowly. Liquids are sometimes used in measuring devices. A thermometer often uses the thermal expansion of liquids, such as mercury , combined with their ability to flow to indicate temperature. A manometer uses the weight of the liquid to indicate air pressure . The free surface of

2781-519: Is generally a chocolate or cornstarch-based sludge used more for visual appeal than actual taste. However, it does not contain real mud. A mud bath is a bath of mud, commonly from areas where hot spring water can combine with volcanic ash . Mud baths have existed for thousands of years, and can be found now in high-end spas . Mud wallows are a common source of entertainment for children . Mud wallows can be any shape, size, depth and some can have water as well as mud. Usually wallows are shallow dips in

2884-408: Is given by where: For a body of water open to the air, p 0 {\displaystyle p_{0}} would be the atmospheric pressure . Static liquids in uniform gravitational fields also exhibit the phenomenon of buoyancy , where objects immersed in the liquid experience a net force due to the pressure variation with depth. The magnitude of the force is equal to the weight of

2987-437: Is important since machinery often operate over a range of temperatures (see also viscosity index ). The viscous behavior of a liquid can be either Newtonian or non-Newtonian . A Newtonian liquid exhibits a linear strain/stress curve, meaning its viscosity is independent of time, shear rate, or shear-rate history. Examples of Newtonian liquids include water, glycerin , motor oil , honey , or mercury. A non-Newtonian liquid

3090-400: Is mostly clay, or a mixture of clay and sand may be used for ceramics , of which one form is the common fired brick . Fired brick are more durable but consume much more energy to produce. Stabilized mud (earth, soil) is mud which has had a binder such as cement or bitumen added. Examples are mudcrete , landcrete, and soil cement . Pottery is made by forming a clay body into objects of

3193-473: Is no equilibrium at this transition under constant pressure, so unless supercooling occurs, the liquid will eventually completely crystallize. However, this is only true under constant pressure, so that (for example) water and ice in a closed, strong container might reach an equilibrium where both phases coexist. For the opposite transition from solid to liquid, see melting . The phase diagram explains why liquids do not exist in space or any other vacuum. Since

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3296-805: Is of vital importance in chemistry and biology, and it is necessary for all known forms of life. Inorganic liquids include water, magma , inorganic nonaqueous solvents and many acids . Important everyday liquids include aqueous solutions like household bleach , other mixtures of different substances such as mineral oil and gasoline, emulsions like vinaigrette or mayonnaise , suspensions like blood, and colloids like paint and milk . Many gases can be liquefied by cooling, producing liquids such as liquid oxygen , liquid nitrogen , liquid hydrogen and liquid helium . Not all gases can be liquified at atmospheric pressure, however. Carbon dioxide , for example, can only be liquified at pressures above 5.1 atm . Some materials cannot be classified within

3399-435: Is one where the viscosity is not independent of these factors and either thickens (increases in viscosity) or thins (decreases in viscosity) under shear. Examples of non-Newtonian liquids include ketchup , custard , or starch solutions. The speed of sound in a liquid is given by c = K / ρ {\displaystyle c={\sqrt {K/\rho }}} where K {\displaystyle K}

3502-447: Is responsible for a range of other phenomena as well, including surface waves , capillary action , wetting , and ripples . In liquids under nanoscale confinement , surface effects can play a dominating role since – compared with a macroscopic sample of liquid – a much greater fraction of molecules are located near a surface. The surface tension of a liquid directly affects its wettability . Most common liquids have tensions ranging in

3605-425: Is the bulk modulus of the liquid and ρ {\displaystyle \rho } the density. As an example, water has a bulk modulus of about 2.2  GPa and a density of 1000 kg/m , which gives c = 1.5 km/s. At a temperature below the boiling point , any matter in liquid form will evaporate until reaching equilibrium with the reverse process of condensation of its vapor. At this point

3708-405: Is the discipline of safely and efficiently tearing down buildings and other artificial structures . Demolition contrasts with deconstruction , which involves taking a building apart while carefully preserving valuable elements for reuse purposes ( recycling – see also circular economy ). The output of the global construction industry was worth an estimated $ 10.8 trillion in 2017, and in 2018

3811-937: Is the process of adding structures to areas of land, also known as real property sites. Typically, a project is instigated by or with the owner of the property (who may be an individual or an organisation); occasionally, land may be compulsorily purchased from the owner for public use. Residential construction may be undertaken by individual land-owners ( self-built ), by specialist housebuilders , by property developers , by general contractors , or by providers of public or social housing (e.g.: local authorities, housing associations ). Where local zoning or planning policies allow, mixed-use developments may comprise both residential and non-residential construction (e.g.: retail, leisure, offices, public buildings, etc.). Residential construction practices, technologies , and resources must conform to local building authority's regulations and codes of practice . Materials readily available in

3914-413: Is the second largest construction market with a 2018 output of $ 1.581 trillion. Construction is a major source of employment in most countries; high reliance on small businesses, and under-representation of women are common traits. For example: According to McKinsey research, productivity growth per worker in construction has lagged behind many other industries across different countries including in

4017-550: The Bronze Age , a class of professional craftsmen , like bricklayers and carpenters , appeared. Occasionally, slaves were used for construction work. In the Middle Ages , the artisan craftsmen were organized into guilds . In the 19th century, steam-powered machinery appeared, and later, diesel- and electric-powered vehicles such as cranes , excavators and bulldozers . Fast-track construction has been increasingly popular in

4120-482: The Latin word constructio (from com- "together" and struere "to pile up") and Old French construction . To 'construct' is a verb : the act of building, and the noun is construction: how something is built or the nature of its structure. In its most widely used context, construction covers the processes involved in delivering buildings , infrastructure , industrial facilities, and associated activities through to

4223-587: The United States and in European countries. In the United States, construction productivity per worker has declined by half since the 1960s. The twenty-five largest countries in the world by construction GVA (2018) Some workers may be engaged in manual labour as unskilled or semi-skilled workers; they may be skilled tradespeople; or they may be supervisory or managerial personnel. Under safety legislation in

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4326-474: The architect , engineer or builder acts for the client as the project coordinator. They design the works, prepare specifications and design deliverables (models, drawings, etc.), administer the contract, tender the works, and manage the works from inception to completion. In parallel, there are direct contractual links between the client and the main contractor, who, in turn, has direct contractual relationships with subcontractors. The arrangement continues until

4429-1247: The cryogenic distillation of gases such as argon , oxygen , nitrogen , neon , or xenon by liquefaction (cooling them below their individual boiling points). Liquid is the primary component of hydraulic systems, which take advantage of Pascal's law to provide fluid power . Devices such as pumps and waterwheels have been used to change liquid motion into mechanical work since ancient times. Oils are forced through hydraulic pumps , which transmit this force to hydraulic cylinders . Hydraulics can be found in many applications, such as automotive brakes and transmissions , heavy equipment , and airplane control systems. Various hydraulic presses are used extensively in repair and manufacturing, for lifting, pressing, clamping and forming. Liquid metals have several properties that are useful in sensing and actuation , particularly their electrical conductivity and ability to transmit forces (incompressibility). As freely flowing substances, liquid metals retain these bulk properties even under extreme deformation. For this reason, they have been proposed for use in soft robots and wearable healthcare devices , which must be able to operate under repeated deformation. The metal gallium

4532-709: The operating temperature range of the component. Oils are often used in engines, gear boxes , metalworking , and hydraulic systems for their good lubrication properties. Many liquids are used as solvents , to dissolve other liquids or solids. Solutions are found in a wide variety of applications, including paints , sealants , and adhesives . Naphtha and acetone are used frequently in industry to clean oil, grease, and tar from parts and machinery. Body fluids are water-based solutions. Surfactants are commonly found in soaps and detergents . Solvents like alcohol are often used as antimicrobials . They are found in cosmetics, inks , and liquid dye lasers . They are used in

4635-446: The sun . Submerged mud can be home to larvae of various insects . Mud plays an important role in the marine ecosystem . The activities of burrowing animals and fish have a dramatic churning effect on muddy seabeds . This allows the exchange and cycling of oxygen , nutrients , and minerals between water and sediment . Below the surface, the burrows of some species form intricate lattice-like networks and may penetrate

4738-414: The type of building , non-residential building construction can be procured by a wide range of private and public organisations, including local authorities, educational and religious bodies, transport undertakings, retailers, hoteliers, property developers, financial institutions and other private companies. Most construction in these sectors is undertaken by general contractors . Civil engineering covers

4841-438: The western United States during El Niño years due to prolonged rainfall. Geophagia is the practice of eating earth or soil-like substances, also known as geophagy, and is practiced by some non-human primates and by humans in some cultures. In other human cultures it is considered an eating disorder and classed as Pica . Mississippi mud pie is a chocolate based dessert pie. Children's recipes for "mud" also exist, which

4944-581: The "vast majority of large construction projects go over budget and take 20% longer than expected". A construction project is a complex net of construction contracts and other legal obligations, each of which all parties must carefully consider. A contract is the exchange of a set of obligations between two or more parties, and provides structures to manage issues. For example, construction delays can be costly, so construction contracts set out clear expectations and clear paths to manage delays. Poorly drafted contracts can lead to confusion and costly disputes. At

5047-461: The 21st century. Some estimates suggest that 40% of construction projects are now fast-track construction. Broadly, there are three sectors of construction: buildings, infrastructure and industrial: The industry can also be classified into sectors or markets. For example, Engineering News-Record ( ENR ), a US-based construction trade magazine, has compiled and reported data about the size of design and construction contractors. In 2014, it split

5150-447: The 21st-century introduction of building information modeling (BIM) processes has involved the use of computer-generated models that can be used in their own right or to generate drawings and other visualisations as well as capturing non-geometric data about building components and systems. On some projects, work on-site will not start until design work is largely complete; on others, some design work may be undertaken concurrently with

5253-585: The United Kingdom, for example, construction workers are defined as people "who work for or under the control of a contractor on a construction site"; in Canada, this can include people whose work includes ensuring conformance with building codes and regulations, and those who supervise other workers. Laborers comprise a large grouping in most national construction industries. In the United States, for example, in May 2021

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5356-453: The addition of stones, gravel , straw , lime , and/or bitumen . This material was used a variety of ways to build walls , floors and even roofs . For thousands of years it was common in most parts of the world to build walls using mudbricks or the wattle and daub , rammed earth or cob techniques and cover the surfaces with earthen plaster. Mud can be made into mud bricks, also called adobe , by mixing mud with water, placing

5459-413: The area generally dictate the construction materials used (e.g.: brick versus stone versus timber ). Costs of construction on a per square meter (or per square foot) basis for houses can vary dramatically based on site conditions, access routes, local regulations, economies of scale (custom-designed homes are often more expensive to build) and the availability of skilled tradespeople. Depending upon

5562-554: The asset as an advanced technological system requiring close integration of many sub-systems and their individual components, including sustainability. For buildings, building engineering is an emerging discipline that attempts to meet this new challenge. Traditionally, design has involved the production of sketches , architectural and engineering drawings , and specifications . Until the late 20th century, drawings were largely hand- drafted ; adoption of computer-aided design (CAD) technologies then improved design productivity, while

5665-434: The body. Air trapped within the clay body needs to be removed. This is called de-airing and can be accomplished by a machine called a vacuum pug or manually by wedging . Wedging can also help produce an even moisture content. Once a clay body has been kneaded and de-aired or wedged, it is shaped by a variety of techniques. After shaping it is dried and then fired. In ceramics , the making of liquid mud (called slip )

5768-419: The budget on the job, and a construction manager , design engineer , construction engineer or architect supervises it. Those involved with the design and execution must consider zoning requirements and legal issues, environmental impact of the project, scheduling , budgeting and bidding , construction site safety , availability and transportation of building materials , logistics, and inconvenience to

5871-470: The cavities left by the bubbles with tremendous localized force, eroding any adjacent solid surface. In a gravitational field , liquids exert pressure on the sides of a container as well as on anything within the liquid itself. This pressure is transmitted in all directions and increases with depth. If a liquid is at rest in a uniform gravitational field, the pressure p {\displaystyle p} at depth z {\displaystyle z}

5974-459: The classical three states of matter. For example, liquid crystals (used in liquid-crystal displays ) possess both solid-like and liquid-like properties, and belong to their own state of matter distinct from either liquid or solid. Liquids are useful as lubricants due to their ability to form a thin, freely flowing layer between solid materials. Lubricants such as oil are chosen for viscosity and flow characteristics that are suitable throughout

6077-447: The client enters into separate contracts with the designer (architect or engineer), a construction manager , and individual trade contractors . The client takes on the contractual role, while the construction or project manager provides the active role of managing the separate trade contracts, and ensuring that they complete all work smoothly and effectively together. This approach is often used to speed up procurement processes, to allow

6180-410: The client greater flexibility in design variation throughout the contract, to enable the appointment of individual work contractors, to separate contractual responsibility on each individual throughout the contract, and to provide greater client control. In the industrialized world, construction usually involves the translation of designs into reality. Most commonly (i.e.: in a design-bid-build project),

6283-665: The construction sector employed just over 7.5 million people, of whom just over 820,000 were laborers, while 573,000 were carpenters , 508,000 were electricians , 258,000 were equipment operators and 230,000 were construction managers. Like most business sectors, there is also substantial white-collar employment in construction – 681,000 US workers were recorded by the United States Department of Labor as in 'office and administrative support occupations' in May 2021. Large-scale construction requires collaboration across multiple disciplines. A project manager normally manages

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6386-554: The container. If liquid is placed in a bag, it can be squeezed into any shape. Unlike a gas, a liquid is nearly incompressible, meaning that it occupies nearly a constant volume over a wide range of pressures; it does not generally expand to fill available space in a container but forms its own surface, and it may not always mix readily with another liquid. These properties make a liquid suitable for applications such as hydraulics . Liquid particles are bound firmly but not rigidly. They are able to move around one another freely, resulting in

6489-781: The cubic decimeter, more commonly called the litre (1 dm = 1 L = 0.001 m ), and the cubic centimetre, also called millilitre (1 cm = 1 mL = 0.001 L = 10 m ). The volume of a quantity of liquid is fixed by its temperature and pressure . Liquids generally expand when heated, and contract when cooled. Water between 0 °C and 4 °C is a notable exception. On the other hand, liquids have little compressibility . Water, for example, will compress by only 46.4 parts per million for every unit increase in atmospheric pressure (bar). At around 4000 bar (400 megapascals or 58,000 psi ) of pressure at room temperature water experiences only an 11% decrease in volume. Incompressibility makes liquids suitable for transmitting hydraulic power , because

6592-750: The data into nine market segments: transportation, petroleum , buildings, power, industrial, water, manufacturing, sewage/waste, telecom , hazardous waste , and a tenth category for other projects. ENR used data on transportation, sewage, hazardous waste and water to rank firms as heavy contractors. The Standard Industrial Classification and the newer North American Industry Classification System classify companies that perform or engage in construction into three subsectors: building construction, heavy and civil engineering construction, and specialty trade contractors. There are also categories for professional services firms (e.g., engineering , architecture , surveying , project management ). Building construction

6695-426: The delivery of services by all businesses, alongside other detailed plans aimed at ensuring legal, timely, on-budget and safe delivery of the specified works. Design, finance, and legal aspects overlap and interrelate. The design must be not only structurally sound and appropriate for the use and location, but must also be financially possible to build, and legal to use. The financial structure must be adequate to build

6798-440: The design provided and must pay amounts that are legally owed. Legal structures integrate design with other activities and enforce financial and other construction processes. These processes also affect procurement strategies. Clients may, for example, appoint a business to design the project, after which a competitive process is undertaken to appoint a lead contractor to construct the asset ( design–bid–build ); they may appoint

6901-451: The design team is employed by (i.e. in contract with) the property owner. Depending upon the type of project, a design team may include architects , civil engineers , mechanical engineers , electrical engineers , structural engineers , fire protection engineers , planning consultants , architectural consultants, and archaeological consultants. A 'lead designer' will normally be identified to help coordinate different disciplinary inputs to

7004-821: The design, construction, and maintenance of the physical and naturally built environment , including public works such as roads, bridges, canals, dams, tunnels, airports, water and sewerage systems, pipelines, and railways. Some general contractors have expertise in civil engineering; civil engineering contractors are firms dedicated to work in this sector, and may specialise in particular types of infrastructure. Industrial construction includes offshore construction (mainly of energy installations: oil and gas platforms , wind power ), mining and quarrying , refineries , breweries , distilleries and other processing plants, power stations , steel mills , warehouses and factories . Some construction projects are small renovations or repair jobs, like repainting or fixing leaks, where

7107-443: The desire to prevent indisputably bad phenomena, e.g. explosions or bridge collapses. Other legal requirements come from malum prohibitum considerations, or factors that are a matter of custom or expectation, such as isolating businesses from a business district or residences from a residential district. An attorney may seek changes or exemptions in the law that governs the land where the building will be built, either by arguing that

7210-535: The early stages of on-site activity (for example, work on a building's foundations may commence while designers are still working on the detailed designs of the building's internal spaces). Some projects may include elements that are designed for off-site construction (see also prefabrication and modular building ) and are then delivered to the site ready for erection, installation or assembly. Once contractors and other relevant professionals have been appointed and designs are sufficiently advanced, work may commence on

7313-467: The end of their life. It typically starts with planning , financing , and design that continues until the asset is built and ready for use. Construction also covers repairs and maintenance work, any works to expand, extend and improve the asset, and its eventual demolition , dismantling or decommissioning . The construction industry contributes significantly to many countries' gross domestic products ( GDP ). Global expenditure on construction activities

7416-443: The ends of the pipe. The viscosity of liquids decreases with increasing temperature. Precise control of viscosity is important in many applications, particularly the lubrication industry. One way to achieve such control is by blending two or more liquids of differing viscosities in precise ratios. In addition, various additives exist which can modulate the temperature-dependence of the viscosity of lubricating oils. This capability

7519-423: The enormous variation seen in other mechanical properties, such as viscosity. The free surface of a liquid is disturbed by gravity ( flatness ) and waves ( surface roughness ). An important physical property characterizing the flow of liquids is viscosity . Intuitively, viscosity describes the resistance of a liquid to flow. More technically, viscosity measures the resistance of a liquid to deformation at

7622-412: The first feature of the permanent structure has been put in place, such as pile driving, or the pouring of slabs or footings. Commissioning is the process of verifying that all subsystems of a new building (or other assets) work as intended to achieve the owner's project requirements and as designed by the project's architects and engineers. A period after handover (or practical completion) during which

7725-624: The food industry, in processes such as the extraction of vegetable oil . Liquids tend to have better thermal conductivity than gases, and the ability to flow makes a liquid suitable for removing excess heat from mechanical components. The heat can be removed by channeling the liquid through a heat exchanger , such as a radiator , or the heat can be removed with the liquid during evaporation . Water or glycol coolants are used to keep engines from overheating. The coolants used in nuclear reactors include water or liquid metals, such as sodium or bismuth . Liquid propellant films are used to cool

7828-410: The ground that have been flooded and were full of dirt and those two have mixed to make a squishy mud wallow. Mud sports are sports that take place in, or heavily incorporate, mud. Examples include: Construction This is an accepted version of this page Construction is a general term meaning the art and science of forming objects , systems , or organizations . It comes from

7931-477: The individual elements are solid under the same conditions (see eutectic mixture ). An example is the sodium-potassium metal alloy NaK . Other metal alloys that are liquid at room temperature include galinstan , which is a gallium-indium-tin alloy that melts at −19 °C (−2 °F), as well as some amalgams (alloys involving mercury). Pure substances that are liquid under normal conditions include water, ethanol and many other organic solvents. Liquid water

8034-416: The liquid displaced by the object, and the direction of the force depends on the average density of the immersed object. If the density is smaller than that of the liquid, the buoyant force points upward and the object floats, whereas if the density is larger , the buoyant force points downward and the object sinks. This is known as Archimedes' principle . Unless the volume of a liquid exactly matches

8137-534: The mixture into moulds and then allowing it to dry in open air . Straw is sometimes used as a binder within the bricks , as it makes them a composite . When the brick would otherwise break, the straw will redistribute the force throughout the brick, decreasing the chance of breakage . Such buildings must be protected from groundwater , usually by building upon a masonry, fired brick, rock or rubble foundation, and also from wind-driven rain in damp climates , usually by deep roof overhangs. In extremely dry climates

8240-594: The molecules become smaller. When the liquid reaches its freezing point the molecules will usually lock into a very specific order, called crystallizing, and the bonds between them become more rigid, changing the liquid into its solid state (unless supercooling occurs). Only two elements are liquid at standard conditions for temperature and pressure : mercury and bromine . Four more elements have melting points slightly above room temperature : francium , caesium , gallium and rubidium . In addition, certain mixtures of elements are liquid at room temperature, even if

8343-486: The overall budget is adequate, presenting a temporary issue. Cost overruns with government projects have occurred when the contractor identified change orders or project changes that increased costs, which are not subject to competition from other firms as they have already been eliminated from consideration after the initial bid. Fraud is also an issue of growing significance within construction. Large projects can involve highly complex financial plans and often start with

8446-441: The overall design. This may be aided by integration of previously separate disciplines (often undertaken by separate firms) into multi-disciplinary firms with experts from all related fields, or by firms establishing relationships to support design-build processes. The increasing complexity of construction projects creates the need for design professionals trained in all phases of a project's life-cycle and develop an appreciation of

8549-409: The owner may act as designer, paymaster and laborer for the entire project. However, more complex or ambitious projects usually require additional multi-disciplinary expertise and manpower, so the owner may commission one or more specialist businesses to undertake detailed planning, design, construction and handover of the work. Often the owner will appoint one business to oversee the project (this may be

8652-405: The owner may identify any shortcomings in relation to the building specification ('defects'), with a view to the contractor correcting the defect. Maintenance involves functional checks, servicing, repairing or replacing of necessary devices, equipment, machinery , building infrastructure, and supporting utilities in industrial, business, governmental, and residential installations. Demolition

8755-478: The owner's equity in the property is the most obvious source of funding for a building project. Accountants act to study the expected monetary flow over the life of the project and to monitor the payouts throughout the process. Professionals including cost engineers, estimators and quantity surveyors apply expertise to relate the work and materials involved to a proper valuation. Financial planning ensures adequate safeguards and contingency plans are in place before

8858-518: The pressure is essentially zero (except on surfaces or interiors of planets and moons) water and other liquids exposed to space will either immediately boil or freeze depending on the temperature. In regions of space near the Earth, water will freeze if the sun is not shining directly on it and vaporize (sublime) as soon as it is in sunlight. If water exists as ice on the Moon, it can only exist in shadowed holes where

8961-414: The project brief and then selects a preferred supplier. Often this will be a consortium involving a design firm and a contractor (sometimes more than one of each). In the United States, departments of transportation usually use design-build contracts as a way of progressing projects where states lack the skills or resources, particularly for very large projects. In a construction management arrangement,

9064-435: The project is ready for handover. Design-build became more common from the late 20th century, and involves the client contracting a single entity to provide design and construction. In some cases, the design-build package can also include finding the site, arranging funding and applying for all necessary statutory consents. Typically, the client invites several Design & Build (D&B) contractors to submit proposals to meet

9167-405: The project is started, and ensures that the plan is properly executed over the life of the project. Construction projects can suffer from preventable financial problems. Underbids happen when builders ask for too little money to complete the project. Cash flow problems exist when the present amount of funding cannot cover the current costs for labour and materials; such problems may arise even when

9270-518: The project site. Typically, a construction site will include a secure perimeter to restrict unauthorised access, site access control points, office and welfare accommodation for personnel from the main contractor and other firms involved in the project team, and storage areas for materials, machinery and equipment. According to the McGraw-Hill Dictionary of Architecture and Construction's definition, construction may be said to have started when

9373-745: The project will be located) for its potential impacts on neighbouring properties, and upon existing infrastructure (transportation, social infrastructure, and utilities including water supply, sewerage, electricity, telecommunications, etc.). Data may be gathered through site analysis , site surveys and geotechnical investigations . Construction normally cannot start until planning permission has been granted, and may require preparatory work to ensure relevant infrastructure has been upgraded before building work can commence. Preparatory works will also include surveys of existing utility lines to avoid damage-causing outages and other hazardous situations. Some legal requirements come from malum in se considerations, or

9476-628: The public, including those caused by construction delays . Some models and policy-making organisations promote the engagement of local labour in construction projects as a means of tackling social exclusion and addressing skill shortages. In the UK, the Joseph Rowntree Foundation reported in 2000 on 25 projects which had aimed to offer training and employment opportunities for locally based school leavers and unemployed people. The Foundation published "a good practice resource book" in this regard at

9579-647: The same time. Use of local labour and local materials were specified for the construction of the Danish Storebaelt bridge , but there were legal issues which were challenged in court and addressed by the European Court of Justice in 1993. The court held that a contract condition requiring use of local labour and local materials was incompatible with EU treaty principles . Later UK guidance noted that social and employment clauses, where used, must be compatible with relevant EU regulation. Employment of local labour

9682-460: The speed of sound. Another phenomenon caused by liquid's incompressibility is cavitation . Because liquids have little elasticity they can literally be pulled apart in areas of high turbulence or dramatic change in direction, such as the trailing edge of a boat propeller or a sharp corner in a pipe. A liquid in an area of low pressure (vacuum) vaporizes and forms bubbles, which then collapse as they enter high pressure areas. This causes liquid to fill

9785-473: The start of a project, legal advisors seek to identify ambiguities and other potential sources of trouble in the contract structures, and to present options for preventing problems. During projects, they work to avoid and resolve conflicts that arise. In each case, the lawyer facilitates an exchange of obligations that matches the reality of the project. Design-bid-build is the most common and well-established method of construction procurement. In this arrangement,

9888-626: The sun never shines and where the surrounding rock does not heat it up too much. At some point near the orbit of Saturn, the light from the Sun is too faint to sublime ice to water vapor. This is evident from the longevity of the ice that composes Saturn's rings. Liquids can form solutions with gases, solids, and other liquids. Two liquids are said to be miscible if they can form a solution in any proportion; otherwise they are immiscible. As an example, water and ethanol (drinking alcohol) are miscible whereas water and gasoline are immiscible. In some cases

9991-450: The tens of mJ/m , so droplets of oil, water, or glue can easily merge and adhere to other surfaces, whereas liquid metals such as mercury may have tensions ranging in the hundreds of mJ/m , thus droplets do not combine easily and surfaces may only wet under specific conditions. The surface tensions of common liquids occupy a relatively narrow range of values when exposed to changing conditions such as temperature, which contrasts strongly with

10094-732: The thrust chambers of rockets . In machining , water and oils are used to remove the excess heat generated, which can quickly ruin both the work piece and the tooling. During perspiration , sweat removes heat from the human body by evaporating. In the heating, ventilation, and air-conditioning industry (HVAC), liquids such as water are used to transfer heat from one area to another. Liquids are often used in cooking due to their excellent heat-transfer capabilities. In addition to thermal conduction, liquids transmit energy by convection. In particular, because warmer fluids expand and rise while cooler areas contract and sink, liquids with low kinematic viscosity tend to transfer heat through convection at

10197-426: The vapor will condense at the same rate as the liquid evaporates. Thus, a liquid cannot exist permanently if the evaporated liquid is continually removed. A liquid at or above its boiling point will normally boil, though superheating can prevent this in certain circumstances. At a temperature below the freezing point, a liquid will tend to crystallize , changing to its solid form. Unlike the transition to gas, there

10300-405: The volume of its container, one or more surfaces are observed. The presence of a surface introduces new phenomena which are not present in a bulk liquid. This is because a molecule at a surface possesses bonds with other liquid molecules only on the inner side of the surface, which implies a net force pulling surface molecules inward. Equivalently, this force can be described in terms of energy: there

10403-588: Was about $ 4 trillion in 2012. In 2022, expenditure on the construction industry exceeded $ 11 trillion a year, equivalent to about 13 percent of global GDP . This spending was forecasted to rise to around $ 14.8 trillion in 2030. The construction industry promotes economic development and brings many non-monetary benefits to many countries, but it is one of the most hazardous industries. For example, about 20% (1,061) of US industry fatalities in 2019 happened in construction. The first huts and shelters were constructed by hand or with simple tools. As cities grew during

10506-455: Was forecast to rise to $ 12.9 trillion by 2022, and to around $ 14.8 trillion in 2030. As a sector, construction accounts for more than 10% of global GDP (in developed countries , construction comprises 6–9% of GDP), and employs around 7% of the total employed workforce around the globe (accounting for over 273 million full- and part-time jobs in 2014). Since 2010, China has been the world's largest single construction market. The United States

10609-571: Was identified as one of several social issues which could potentially be incorporated in a sustainable procurement approach, although the interdepartmental Sustainable Procurement Group recognised that "there is far less scope to incorporate [such] social issues in public procurement than is the case with environmental issues". There are many routes to the different careers within the construction industry. There are three main tiers of construction workers based on educational background and training, which vary by country: Liquid A liquid

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