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93-592: Chinalco is principally engaged in the extraction of aluminium oxide , electrolysis of virgin aluminium and the processing and production of aluminium as well as traded trading and engineering and technical services. Its primary listing is on the Shanghai Stock Exchange and it is a constituent of the SSE 180 index. It has a secondary listing on the Hong Kong Stock Exchange . The major shareholder of

186-476: 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

279-422: 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

372-533: A 9% stake in the Anglo-Australian mining company Rio Tinto . Rio Tinto controls large Iron ore reserves in Australia . On June 5, Rio Tinto broke a deal for Chinalco to purchase a larger stake in the company, with support by rival Anglo-Australian mining company BHP . Rio Tinto is expected to pay a US$ 195 million breaking fee according to the contract signed earlier by the two parties. In 2010, Chinalco reported

465-445: 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

558-640: 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

651-456: A coating on aluminium by anodizing or by plasma electrolytic oxidation (see the "Properties" above). Both the hardness and abrasion-resistant characteristics of the coating originate from the high strength of aluminium oxide, yet the porous coating layer produced with conventional direct current anodizing procedures is within a 60–70 Rockwell hardness C range which is comparable only to hardened carbon steel alloys, but considerably inferior to

744-479: 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,

837-490: A copper supplier to China, Chinalco announced an investment of $ 1.3 billion to expand copper production after failing to reach its output target last year. The expansion is projected to add 70,000 tonnes a year to the project. Chinalco has invested $ 1.3 billion in its Toromocho mine in 2018, which it acquired in 2007. The project came online in 2013 and is, besides copper, primarily producing silver and molybdenum. The investment constitutes an increase of 45 percent by 2020, with

930-457: A manual dermal abrasive used according to manufacturer directions. Aluminium oxide flakes are used in paint for reflective decorative effects, such as in the automotive or cosmetic industries. Aluminium oxide is a representative of bioinert ceramics. Due to its excellent biocompatibility, high strength, and wear resistance, alumina ceramics are used in medical applications to manufacture artificial bones and joints. In this case, aluminium oxide

1023-405: A material in hip replacements and birth control pills . It is used as a scintillator and dosimeter for radiation protection and therapy applications for its optically stimulated luminescence properties. Insulation for high-temperature furnaces is often manufactured from aluminium oxide. Sometimes the insulation has varying percentages of silica depending on the temperature rating of

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1116-434: A net profit of ¥778.01 million, a dramatic rise when compared with the company's ¥4.62 billion losses from the previous year. The company credits increased prices and effective cost control strategies with the financial turnaround. During July 2011, Chinalco signed a long-term agreement with Mongolian miner Tavan Tolgoi to import more than 15 million tons of coking coal annually to meet increased domestic demand. A subsidiary

1209-545: A proportion of aluminium in the alloy to enhance corrosion resistance. The aluminium oxide generated by anodising is typically amorphous , but discharge-assisted oxidation processes such as plasma electrolytic oxidation result in a significant proportion of crystalline aluminium oxide in the coating, enhancing its hardness . Aluminium oxide was taken off the United States Environmental Protection Agency 's chemicals lists in 1988. Aluminium oxide

1302-412: A relatively high thermal conductivity ( 30 Wm K ) for a ceramic material. Aluminium oxide is insoluble in water. In its most commonly occurring crystalline form, called corundum or α-aluminium oxide, its hardness makes it suitable for use as an abrasive and as a component in cutting tools . Aluminium oxide is responsible for the resistance of metallic aluminium to weathering . Metallic aluminium

1395-467: A research field of interest. Some body armors utilize alumina ceramic plates, usually in combination with aramid or UHMWPE backing to achieve effectiveness against most rifle threats. Alumina ceramic armor is readily available to most civilians in jurisdictions where it is legal, but is not considered military grade. It is also used to produce bullet-proof alumina glass capable to withstand impact of .50 BMG calibre rounds. Aluminium oxide can be grown as

1488-433: 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

1581-472: A tailored product. The type of phases present affects, for example, the solubility and pore structure of the aluminium oxide product which, in turn, affects the cost of aluminium production and pollution control. The Sintering Process is a high-temperature method primarily used when the Bayer Process is not suitable, especially for ores with high silica content or when a more controlled product morphology

1674-799: Is China Aluminum International Engineering (Chalieco) which consists of businesses in engineering design and consultancy, engineering and construction contracting and equipment manufacturing. Chalieco was publicly listed on the Hong Kong Stock Exchange in 2012. Through its aluminum fabrication unit, which was sold in 2013, Chinalco sold casting products, slab band products, foils, squeezing products, forging products, powder products, die-casting products, remelted aluminum ingots, and gallium metal and gallium oxide. These products are used in construction , electricity , packaging , transportation , nondurable consumer goods, hard board material, wire and cable, ceramics , refractory material, laundry , petrochemical , and aerospace industries. As of 2013, Morococha

1767-466: Is a favored filler for plastics. Aluminium oxide is a common ingredient in sunscreen and is often also present in cosmetics such as blush, lipstick, and nail polish. Many formulations of glass have aluminium oxide as an ingredient. Aluminosilicate glass is a commonly used type of glass that often contains 5% to 10% alumina. Aluminium oxide catalyses a variety of reactions that are useful industrially. In its largest scale application, aluminium oxide

1860-566: Is derived, are used in the manufacture of zeolites , coating titania pigments, and as a fire retardant/smoke suppressant. Over 90% of aluminium oxide, termed smelter grade alumina (SGA), is consumed for the production of aluminium, usually by the Hall–Héroult process . The remainder, termed specialty alumina , is used in a wide variety of applications which take advantage of its inertness, temperature resistance and electrical resistance. Being fairly chemically inert and white, aluminium oxide

1953-455: Is on the EPA's Toxics Release Inventory list if it is a fibrous form. Aluminium oxide is an amphoteric substance, meaning it can react with both acids and bases , such as hydrofluoric acid and sodium hydroxide , acting as an acid with a base and a base with an acid, neutralising the other and producing a salt. The most common form of crystalline aluminium oxide is known as corundum , which

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2046-456: Is required. Firstly, Bauxite is mixed with additives like limestone and soda ash, then heating the mixture at high temperatures (1200 °C to 1500 °C) to form sodium aluminate and calcium silicate . After sintering, the material is leached with water to dissolve the sodium aluminate , leaving behind impurities. Sodium aluminate is then precipitated from the solution and calcined at around 1000 °C to produce alumina. This method

2139-483: Is the catalyst in the Claus process for converting hydrogen sulfide waste gases into elemental sulfur in refineries. It is also useful for dehydration of alcohols to alkenes . Aluminium oxide serves as a catalyst support for many industrial catalysts, such as those used in hydrodesulfurization and some Ziegler–Natta polymerizations. Aluminium oxide is widely used to remove water from gas streams. Aluminium oxide

2232-405: 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

2325-937: 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

2418-413: 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

2511-565: Is the thermodynamically stable form. The oxygen ions form a nearly hexagonal close-packed structure with the aluminium ions filling two-thirds of the octahedral interstices. Each Al center is octahedral . In terms of its crystallography , corundum adopts a trigonal Bravais lattice with a space group of R 3 c (number 167 in the International Tables). The primitive cell contains two formula units of aluminium oxide. Aluminium oxide also exists in other metastable phases, including

2604-490: Is used as a superior polishing abrasive in watchmaking and clockmaking. Aluminium oxide is also used in the coating of stanchions in the motocross and mountain bike industries. This coating is combined with molybdenumdisulfate to provide long term lubrication of the surface. 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

2697-538: Is used as an insulating barrier in capacitors . In lighting, translucent aluminium oxide is used in some sodium vapor lamps . Aluminium oxide is also used in preparation of coating suspensions in compact fluorescent lamps . In chemistry laboratories, aluminium oxide is a medium for chromatography , available in basic (pH 9.5), acidic (pH 4.5 when in water) and neutral formulations. Additionally, small pieces of aluminium oxide are often used as boiling chips . Health and medical applications include it as

2790-495: Is used for its hardness and strength. Its naturally occurring form, corundum , is a 9 on the Mohs scale of mineral hardness (just below diamond). It is widely used as an abrasive , including as a much less expensive substitute for industrial diamond . Many types of sandpaper use aluminium oxide crystals. In addition, its low heat retention and low specific heat make it widely used in grinding operations, particularly cutoff tools. As

2883-409: Is used to coat the surfaces of medical implants to give biocompatibility and corrosion resistance. It is also used for manufacturing dental implants, joint replacements, and other medical devices. Aluminium oxide has been used in a few experimental and commercial fiber materials for high-performance applications (e.g., Fiber FP, Nextel 610, Nextel 720). Alumina nanofibers in particular have become

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2976-420: Is used to manufacture tiles which are attached inside pulverized fuel lines and flue gas ducting on coal fired power stations to protect high wear areas. They are not suitable for areas with high impact forces as these tiles are brittle and susceptible to breakage. Aluminium oxide is an electrical insulator used as a substrate ( silicon on sapphire ) for integrated circuits , but also as a tunnel barrier for

3069-600: Is useful for the production of complex shapes and can be used to create porous or dense materials. Known as alpha alumina in materials science , and as alundum (in fused form) or aloxite in mining and ceramic communities, aluminium oxide finds wide use. Annual global production of aluminium oxide in 2015 was approximately 115 million tonnes , over 90% of which was used in the manufacture of aluminium metal. The major uses of speciality aluminium oxides are in refractories, ceramics, polishing and abrasive applications. Large tonnages of aluminium hydroxide, from which alumina

3162-436: Is very reactive with atmospheric oxygen, and a thin passivation layer of aluminium oxide (4 nm thickness) forms on any exposed aluminium surface in a matter of hundreds of picoseconds. This layer protects the metal from further oxidation. The thickness and properties of this oxide layer can be enhanced using a process called anodising . A number of alloys , such as aluminium bronzes , exploit this property by including

3255-550: 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

3348-482: 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

3441-587: 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

3534-474: 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

3627-410: The chemical formula Al 2 O 3 . It is the most commonly occurring of several aluminium oxides , and specifically identified as aluminium oxide . It is commonly called alumina and may also be called aloxide , aloxite , or alundum in various forms and applications. It occurs naturally in its crystalline polymorphic phase α-Al 2 O 3 as the mineral corundum , varieties of which form

3720-414: 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

3813-581: 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

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3906-681: The 2005 failed attempt by China National Offshore Oil Corporation (CNOOC) to buy Unocal Corporation (which ultimately sold to Chevron Corporation for $ 1.5 billion less than CNOOC's offer), the failed Rio Tinto deal was perceived in China as part of a coordinated effort in the West to stall China's rise. Chinalco is investing $ 3 billion to begin open-cast mining operations, within three to four years, in Morococha District , Peru . The company plans to extract copper ore from Mount Toromocho . Chinalco holds

3999-461: 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

4092-447: 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

4185-462: The Al are surrounded by 4 oxygen neighbors), and 1/3 5-coordinated, with very little (<5%) octahedral Al-O present. Around 80% of the oxygen atoms are shared among three or more Al-O polyhedra, and the majority of inter-polyhedral connections are corner-sharing, with the remaining 10–20% being edge-sharing. The breakdown of octahedra upon melting is accompanied by a relatively large volume increase (~33%),

4278-830: The People's Republic of China in 2001. It is the parent company of Aluminum Corporation of China Limited (Chalco) which is listed on the New York , Hong Kong and Shanghai stock exchanges. Effective from 10 June 2008, Chalco was added to the Hang Seng Index Constituent Stock ( blue chip ). In 2009, mining giant Rio Tinto declined a contemplated deal in which Chalco would pay $ 19.5 billion in order to increase its stake in Rio Tinto. Rio Tinto ultimately declined because "there are lots of Aussies in high political places who don't want ... land and resources sold to China." Along with

4371-585: 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

4464-413: 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

4557-554: 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

4650-499: The basic mixture, Fe 2 O 3 is removed. When the Bayer liquor is cooled, Al(OH) 3 precipitates, leaving the silicates in solution. The solid Al(OH) 3 Gibbsite is then calcined (heated to over 1100 °C) to give aluminium oxide: The product aluminium oxide tends to be multi-phase, i.e., consisting of several phases of aluminium oxide rather than solely corundum . The production process can therefore be optimized to produce

4743-419: 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

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4836-429: The chemical exchange between trimethylaluminium (Al(CH 3 ) 3 ) and H 2 O: H 2 O in the above reaction can be replaced by ozone (O 3 ) as the active oxidant and the following reaction then takes place: The Al 2 O 3 films prepared using O 3 show 10–100 times lower leakage current density compared with those prepared by H 2 O. Aluminium oxide, being a dielectric with relatively large band gap ,

4929-447: 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

5022-410: 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),

5115-597: The company was Aluminum Corporation of China known as Chinalco ( Chinese : 中国铝业公司 ), a state owned enterprise. The company has a number of distinct business segments including (1) alumina refining, (2) primary aluminum smelting, and (3) energy. The alumina refining segment consists of mining and purchasing bauxite, refining bauxite into alumina, and production and sales of alumina chemicals and metal gallium. The aluminum smelting segment smelts alumina to produce primary aluminum and also produces carbon products, aluminum alloy products, and other aluminum products. Finally

5208-665: 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

5301-427: The cubic γ and η phases, the monoclinic θ phase, the hexagonal χ phase, the orthorhombic κ phase and the δ phase that can be tetragonal or orthorhombic. Each has a unique crystal structure and properties. Cubic γ-Al 2 O 3 has important technical applications. The so-called β-Al 2 O 3 proved to be NaAl 11 O 17 . Molten aluminium oxide near the melting temperature is roughly 2/3 tetrahedral (i.e. 2/3 of

5394-750: 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

5487-426: 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

5580-405: The density of the liquid close to its melting point is 2.93 g/cm . The structure of molten alumina is temperature dependent and the fraction of 5- and 6-fold aluminium increases during cooling (and supercooling), at the expense of tetrahedral AlO 4 units, approaching the local structural arrangements found in amorphous alumina. Aluminium hydroxide minerals are the main component of bauxite ,

5673-440: 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

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5766-451: 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

5859-821: 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

5952-443: 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

6045-535: 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

6138-467: 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

6231-427: The energy segment produces coal, generates electricity from coal, develops wind and solar power, manufactures new energy equipment, and integrates coal electricity generation with aluminum operations. Until 2013, it was also engaged in aluminum fabrication but has since sold this business line. Aluminum Corporation of China (Chinalco) is a state-backed holding company established to be the primary aluminium producer in

6324-403: The fabrication of superconducting devices such as single-electron transistors , superconducting quantum interference devices ( SQUIDs ) and superconducting qubits . For its application as an electrical insulator in integrated circuits, where the conformal growth of a thin film is a prerequisite and the preferred growth mode is atomic layer deposition , Al 2 O 3 films can be prepared by

6417-412: 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

6510-438: The hardness of natural and synthetic corundum. Instead, with plasma electrolytic oxidation , the coating is porous only on the surface oxide layer while the lower oxide layers are much more compact than with standard DC anodizing procedures and present a higher crystallinity due to the oxide layers being remelted and densified to obtain α-Al2O3 clusters with much higher coating hardness values circa 2000 Vickers hardness. Alumina

6603-499: The material. The insulation can be made in blanket, board, brick and loose fiber forms for various application requirements. It is also used to make spark plug insulators . Using a plasma spray process and mixed with titania , it is coated onto the braking surface of some bicycle rims to provide abrasion and wear resistance. Most ceramic eyes on fishing rods are circular rings made from aluminium oxide. In its finest powdered (white) form, called Diamantine, aluminium oxide

6696-400: The mineral deltalumite. The field of aluminium oxide ceramics has a long history. Aluminium salts were widely used in ancient and medieval alchemy . Several older textbooks cover the history of the field. A 2019 textbook by Andrew Ruys contains a detailed timeline on the history of aluminium oxide from ancient times to the 21st century. Al 2 O 3 is an electrical insulator but has

6789-486: 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

6882-441: 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

6975-409: 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

7068-405: 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

7161-478: 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

7254-408: The powdery abrasive mineral aloxite , it is a major component, along with silica , of the cue tip "chalk" used in billiards . Aluminium oxide powder is used in some CD / DVD polishing and scratch-repair kits. Its polishing qualities are also behind its use in toothpaste. It is also used in microdermabrasion , both in the machine process available through dermatologists and estheticians, and as

7347-657: The precious gemstones ruby and sapphire . Al 2 O 3 is used to produce aluminium metal, as an abrasive owing to its hardness , and as a refractory material owing to its high melting point. Corundum is the most common naturally occurring crystalline form of aluminium oxide. Rubies and sapphires are gem-quality forms of corundum, which owe their characteristic colours to trace impurities. Rubies are given their characteristic deep red colour and their laser qualities by traces of chromium . Sapphires come in different colours given by various other impurities, such as iron and titanium. An extremely rare δ form occurs as

7440-489: The principal ore of aluminium . A mixture of the minerals comprise bauxite ore, including gibbsite (Al(OH) 3 ), boehmite (γ-AlO(OH)), and diaspore (α-AlO(OH)), along with impurities of iron oxides and hydroxides, quartz and clay minerals . Bauxites are found in laterites . Bauxite is typically purified using the Bayer process : Except for SiO 2 , the other components of bauxite do not dissolve in base. Upon filtering

7533-414: 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,

7626-435: 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

7719-405: 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

7812-518: 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

7905-745: 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

7998-628: 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

8091-647: 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

8184-473: 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,

8277-415: The value of production from this move expected to exceed $ 2 billion. In 2011, China Aluminum Corporation and Rio Tinto , the world's second largest mining company, created a joint venture in order to explore deposits in China. According to Rio Tinto chief executive Tom Albanese , the joint venture was meant to be “an important milestone in the expanding relationship between Rio Tinto and China.” Chinalco

8370-588: 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

8463-455: 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

8556-415: Was the majority stakeholder of the project, holding 51% of shares, while Rio Tinto held 49%. On January 18, 2017, it was reported that the two corporations had terminated the joint venture, and had begun to liquidate the joint venture company, Chinalco Rio Tinto Exploration Co. Aluminium oxide Aluminium oxide (or aluminium(III) oxide ) is a chemical compound of aluminium and oxygen with

8649-402: Was the site of a planned open pit copper mine to be operated by Aluminum Corporation of China Limited. A new town for the 5,000 residents of Morococha has been built about 6 miles away, but some residents were reported to be resisting relocation. The mine is projected to produce about 250,000 tons of copper a year for about 35 years. In April 2017, owing to Peru 's increasing importance as

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