73-460: The Zilwaukee Bridge is a high-level, segmental concrete bridge spanning the Saginaw River in the U.S. state of Michigan . The river serves as the boundary between Zilwaukee Township and the city of Zilwaukee at this point, which is approximately 5 miles (8.0 km) north of downtown Saginaw . It carries Interstate 75 and US 23 . The current eight-lane structure, completed in 1988,
146-479: A Democrat for president , and has only failed to endorse a Republican presidential candidate five times: twice during the Franklin D. Roosevelt era; in 2004, when it did not endorse George W. Bush for re-election; in 2016, when it endorsed Libertarian Party nominee Gary Johnson rather than Republican nominee Donald Trump , and in 2020, when it continued to withhold its endorsement from Trump and did not endorse
219-411: A calcium aluminate cement or with Portland cement to form Portland cement concrete (named for its visual resemblance to Portland stone ). Many other non-cementitious types of concrete exist with other methods of binding aggregate together, including asphalt concrete with a bitumen binder, which is frequently used for road surfaces , and polymer concretes that use polymers as a binder. Concrete
292-433: A French structural and civil engineer . Concrete components or structures are compressed by tendon cables during, or after, their fabrication in order to strengthen them against tensile forces developing when put in service. Freyssinet patented the technique on 2 October 1928. Concrete is an artificial composite material , comprising a matrix of cementitious binder (typically Portland cement paste or asphalt ) and
365-587: A candidate. The staff of The Detroit News includes editorial page columnists Nolan Finley, Kaitlyn Buss and Bankole Thompson; design writer Maureen Feighan; food critic Melody Baetens; sports columnists Bob Wojnowski and John Niyo; sportswriters Angelique Chengelis, Tony Paul, Justin Rogers, Chris McCosky, Mike Curtis, Rod Beard, David Goricki, Matt Charboneau, Nolan Bianchi, Ted Kulfan and James Hawkins; auto critic Henry Payne and business columnist Daniel Howes . The staff also includes metro reporter Robert Snell, who
438-452: A cementitious material forms a cement paste by the process of hydration. The cement paste glues the aggregate together, fills voids within it, and makes it flow more freely. As stated by Abrams' law , a lower water-to-cement ratio yields a stronger, more durable concrete, whereas more water gives a freer-flowing concrete with a higher slump . The hydration of cement involves many concurrent reactions. The process involves polymerization ,
511-400: A concrete component—and become a part of the binder for the aggregate. Fly ash and slag can enhance some properties of concrete such as fresh properties and durability. Alternatively, other materials can also be used as a concrete binder: the most prevalent substitute is asphalt , which is used as the binder in asphalt concrete . Admixtures are added to modify the cure rate or properties of
584-434: A dispersed phase or "filler" of aggregate (typically a rocky material, loose stones, and sand). The binder "glues" the filler together to form a synthetic conglomerate . Many types of concrete are available, determined by the formulations of binders and the types of aggregate used to suit the application of the engineered material. These variables determine strength and density, as well as chemical and thermal resistance of
657-452: A greater degree of fracture resistance even in seismically active environments. Roman concrete is significantly more resistant to erosion by seawater than modern concrete; it used pyroclastic materials which react with seawater to form Al- tobermorite crystals over time. The use of hot mixing and the presence of lime clasts are thought to give the concrete a self-healing ability, where cracks that form become filled with calcite that prevents
730-429: A hard matrix that binds the materials together into a durable stone-like material that has many uses. This time allows concrete to not only be cast in forms, but also to have a variety of tooled processes performed. The hydration process is exothermic , which means ambient temperature plays a significant role in how long it takes concrete to set. Often, additives (such as pozzolans or superplasticizers ) are included in
803-415: A large aggregate that is too large for the size of the formwork, or which has too few smaller aggregate grades to serve to fill the gaps between the larger grades, or using too little or too much sand for the same reason, or using too little water, or too much cement, or even using jagged crushed stone instead of smoother round aggregate such as pebbles. Any combination of these factors and others may result in
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#1732858422394876-461: A large type of industrial facility called a concrete plant , or often a batch plant. The usual method of placement is casting in formwork , which holds the mix in shape until it has set enough to hold its shape unaided. Concrete plants come in two main types, ready-mix plants and central mix plants. A ready-mix plant blends all of the solid ingredients, while a central mix does the same but adds water. A central-mix plant offers more precise control of
949-405: A mix which is too harsh, i.e., which does not flow or spread out smoothly, is difficult to get into the formwork, and which is difficult to surface finish. The Detroit News The Detroit News is one of the two major newspapers in the U.S. city of Detroit , Michigan . The paper began in 1873, when it rented space in the rival Detroit Free Press 's building. The News absorbed
1022-469: A mixture of calcium silicates ( alite , belite ), aluminates and ferrites —compounds, which will react with water. Portland cement and similar materials are made by heating limestone (a source of calcium) with clay or shale (a source of silicon, aluminium and iron) and grinding this product (called clinker ) with a source of sulfate (most commonly gypsum ). Cement kilns are extremely large, complex, and inherently dusty industrial installations. Of
1095-405: A number of manufactured aggregates, including air-cooled blast furnace slag and bottom ash are also permitted. The size distribution of the aggregate determines how much binder is required. Aggregate with a very even size distribution has the biggest gaps whereas adding aggregate with smaller particles tends to fill these gaps. The binder must fill the gaps between the aggregate as well as paste
1168-424: A semi-liquid slurry (paste) that can be shaped, typically by pouring it into a form. The concrete solidifies and hardens through a chemical process called hydration . The water reacts with the cement, which bonds the other components together, creating a robust, stone-like material. Other cementitious materials, such as fly ash and slag cement , are sometimes added—either pre-blended with the cement or directly as
1241-426: A separate website for connections from European Union countries that does not track personal information. The Detroit News has won three Pulitzer Prizes . The Detroit News was founded by James E. Scripps , who, in turn, was the older half-brother and one-time partner of Edward W. Scripps . The paper's eventual success, however, is largely credited to Scripps' son-in-law, George Gough Booth , who came aboard at
1314-493: A simple, fast way of getting a basic idea of the properties of the finished concrete without having to perform testing in advance. Various governing bodies (such as British Standards ) define nominal mix ratios into a number of grades, usually ranging from lower compressive strength to higher compressive strength. The grades usually indicate the 28-day cure strength. Thorough mixing is essential to produce uniform, high-quality concrete. Separate paste mixing has shown that
1387-483: A steel reinforcement on the exterior of the bridge to ensure that the structural integrity of the bridge continues to remain sound. On October 21, 2008, the bridge opened up to north and southbound traffic once again. On December 7, 2012, The Detroit News reported that a $ 70 million MDOT program would commence the following April to replace 154 bearings, rebuild 4 miles of I-75, replace the Janes Road bridge, and repair
1460-511: Is distinct from mortar . Whereas concrete is itself a building material, mortar is a bonding agent that typically holds bricks , tiles and other masonry units together. Grout is another material associated with concrete and cement. It does not contain coarse aggregates and is usually either pourable or thixotropic , and is used to fill gaps between masonry components or coarse aggregate which has already been put in place. Some methods of concrete manufacture and repair involve pumping grout into
1533-678: Is still called " Times Square ." The Evening News Association, owner of The News , merged with Gannett in 1985. At the time of its acquisition of The News , Gannett also had other Detroit interests, as its outdoor advertising company, which ultimately became Outfront Media through a series of mergers, operated many billboards across Detroit and the surrounding area, including advertising displays on Detroit Department of Transportation and Southeastern Michigan Transportation Authority buses, with its only competitor, primarily along Metro Detroit's freeway network , being 3M National Advertising (now Lamar Advertising ). The News claims to have been
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#17328584223941606-518: Is the second such bridge at this location, replacing a four-lane bascule bridge constructed in 1960. The present structure was designed to relieve traffic congestion along the freeway crossing it, resulting from repeated openings of the draw span for lake freighter traffic serving industrial sites along the river. The Zilwaukee Bridge is approximately 8,000 feet (2,400 m) in length and rises 125 feet (38 m) at its highest point. Construction of Interstate 75 and US 23 through Saginaw County
1679-476: Is the second-most-used substance in the world after water , and is the most widely used building material. Its usage worldwide, ton for ton, is twice that of steel, wood, plastics, and aluminium combined. When aggregate is mixed with dry Portland cement and water , the mixture forms a fluid slurry that is easily poured and molded into shape. The cement reacts with the water through a process called concrete hydration that hardens it over several hours to form
1752-559: Is then blended with aggregates and any remaining batch water and final mixing is completed in conventional concrete mixing equipment. Workability is the ability of a fresh (plastic) concrete mix to fill the form/mold properly with the desired work (pouring, pumping, spreading, tamping, vibration) and without reducing the concrete's quality. Workability depends on water content, aggregate (shape and size distribution), cementitious content and age (level of hydration ) and can be modified by adding chemical admixtures, like superplasticizer. Raising
1825-399: Is usually reinforced with materials that are strong in tension, typically steel rebar . The mix design depends on the type of structure being built, how the concrete is mixed and delivered, and how it is placed to form the structure. Portland cement is the most common type of cement in general usage. It is a basic ingredient of concrete, mortar , and many plasters . It consists of
1898-683: The Detroit Tribune on February 1, 1919, the Detroit Journal on July 21, 1922, and on November 7, 1960, it bought and closed the faltering Detroit Times . However, it retained the Times building, which it used as a printing plant until 1975, when a new facility opened in Sterling Heights. The Times building was demolished in 1978. The street in downtown Detroit where the Times building once stood
1971-465: The CSX and Wadsworth Road rail bridges in the area. The work was completed in 2015 and was expected to extend the life of the bridge until 2087. During 2014, special custom-made jacks were put into place as a stop-gap measure while bearings were replaced. Concrete Concrete is a composite material composed of aggregate bonded together with a fluid cement that cures to a solid over time. Concrete
2044-528: The Free Press from the Knight Ridder company. With this move, Gannett became the managing partner in the papers' joint operating agreement. On May 7, 2006, the combined Sunday Detroit News and Free Press was replaced by a stand-alone Sunday Free Press . On December 16, 2008, Detroit Media Partnership announced a plan to limit weekday home delivery for both dailies to Thursday and Friday only. On other weekdays
2117-480: The construction industry , whose demand is ever growing with greater impacts on raw material extraction, waste generation and landfill practices. Concrete production is the process of mixing together the various ingredients—water, aggregate, cement, and any additives—to produce concrete. Concrete production is time-sensitive. Once the ingredients are mixed, workers must put the concrete in place before it hardens. In modern usage, most concrete production takes place in
2190-519: The M-13 interchange on the bridge approach, workers uncovered an uncharted landfill containing PCB -contaminated waste, necessitating an environmental cleanup . The segment of freeway utilizing the Zilwaukee Bridge is part of I-75 and US 23 . Many Michiganders consider the bridge to be the start of Up North. I-675 was built, in part, to help traffic bypass the original drawbridge while
2263-639: The absence of reinforcement, its tensile strength was far lower than modern reinforced concrete , and its mode of application also differed: Modern structural concrete differs from Roman concrete in two important details. First, its mix consistency is fluid and homogeneous, allowing it to be poured into forms rather than requiring hand-layering together with the placement of aggregate, which, in Roman practice, often consisted of rubble . Second, integral reinforcing steel gives modern concrete assemblies great strength in tension, whereas Roman concrete could depend only upon
Zilwaukee Bridge - Misplaced Pages Continue
2336-414: The bridge was roughly two-thirds completed, and a 150-foot (46 m) long segment weighing 6,700-ton (6,070 metric tonnes), not being properly counterbalanced, tipped down to being five feet (1.5 m) out of alignment, with the other end rising 3.5 feet (1.1 m). A pier footing cracked, presumably due to resulting stress . Once repairs were made, a new contractor was hired to complete the bridge once
2409-409: The bridge's piers after navigating a sharp bend in the river just before the bridge. These complications led to proposals for a replacement bridge with a higher span. Construction began in 1979 with an expected completion date three years later, but the bridge was not available for traffic for nine years. The initial budget of $ 79 million had already been exceeded by $ 48 million, when at time in 1982,
2482-610: The cisterns secret as these enabled the Nabataeans to thrive in the desert. Some of these structures survive to this day. In the Ancient Egyptian and later Roman eras, builders discovered that adding volcanic ash to lime allowed the mix to set underwater. They discovered the pozzolanic reaction . The Romans used concrete extensively from 300 BC to AD 476. During the Roman Empire, Roman concrete (or opus caementicium )
2555-526: The concrete at the time of batching/mixing. (See § Production below.) The common types of admixtures are as follows: Inorganic materials that have pozzolanic or latent hydraulic properties, these very fine-grained materials are added to the concrete mix to improve the properties of concrete (mineral admixtures), or as a replacement for Portland cement (blended cements). Products which incorporate limestone , fly ash , blast furnace slag , and other useful materials with pozzolanic properties into
2628-399: The concrete can cause the initially placed material to begin to set before the next batch is added on top. This creates a horizontal plane of weakness called a cold joint between the two batches. Once the mix is where it should be, the curing process must be controlled to ensure that the concrete attains the desired attributes. During concrete preparation, various technical details may affect
2701-461: The concrete quality. Central mix plants must be close to the work site where the concrete will be used, since hydration begins at the plant. A concrete plant consists of large hoppers for storage of various ingredients like cement, storage for bulk ingredients like aggregate and water, mechanisms for the addition of various additives and amendments, machinery to accurately weigh, move, and mix some or all of those ingredients, and facilities to dispense
2774-519: The crack from spreading. The widespread use of concrete in many Roman structures ensured that many survive to the present day. The Baths of Caracalla in Rome are just one example. Many Roman aqueducts and bridges, such as the magnificent Pont du Gard in southern France, have masonry cladding on a concrete core, as does the dome of the Pantheon . After the Roman Empire, the use of burned lime and pozzolana
2847-506: The current high-level Zilwaukee Bridge was being proposed and constructed, in addition to providing better access into and through downtown Saginaw . During bridge maintenance, I-675 is used as a detour route for traffic. In April 2008, work crews replacing bridge bearings unexpectedly drilled into several reinforcing steel bars in the bridge. The $ 3.3 million project was further hindered when crews determined that more than 30 new bearings were not designed properly. MDOT said crews erected
2920-482: The east and south side of the building were bricked-in for protection after the 12th Street Riot in 1967. The bricked-in arches on the east and south ends of the building were reopened during renovations required when the Free Press relocated its offices there 20 years later. In 1931, The Detroit News made history when it bought a three-place Pitcairn PCA-2 auto-gyro as a camera aircraft that could take off and land in restricted places and semi-hover for photos. It
2993-416: The exterior similar to those on the former offices. The move took place October 24–27, 2014. Editorially, The News is considered more conservative than the Free Press. However, it considers itself libertarian . In an editorial statement printed in 1958, The News described itself as consistently conservative on economic issues and consistently liberal on civil liberties issues. It has never endorsed
Zilwaukee Bridge - Misplaced Pages Continue
3066-431: The finished product. Construction aggregates consist of large chunks of material in a concrete mix, generally a coarse gravel or crushed rocks such as limestone , or granite , along with finer materials such as sand . Cement paste, most commonly made of Portland cement , is the most prevalent kind of concrete binder. For cementitious binders, water is mixed with the dry cement powder and aggregate, which produces
3139-477: The first newspaper in the world to operate a radio station, station 8MK, which began broadcasting August 20, 1920. 8MK is now CBS-owned WWJ . In 1947, it established Michigan's first television station, WWJ-TV, now WDIV-TV ; it has been a primary NBC affiliate since sign-on, owing to WWJ-AM's ties with the NBC Radio Network. In 1989, the paper entered into a one hundred year joint operating agreement with
3212-669: The gaps to make up a solid mass in situ . The word concrete comes from the Latin word " concretus " (meaning compact or condensed), the perfect passive participle of " concrescere ", from " con -" (together) and " crescere " (to grow). Concrete floors were found in the royal palace of Tiryns , Greece, which dates roughly to 1400 to 1200 BC. Lime mortars were used in Greece, such as in Crete and Cyprus, in 800 BC. The Assyrian Jerwan Aqueduct (688 BC) made use of waterproof concrete . Concrete
3285-537: The initial contractor (Stevin Construction) and the state agreed to terminate their contract in exchange for both sides dropping their lawsuits over the accident. The new contractor developed a method of heating the concrete to allow construction during the winter. On some cold days these new sections could not be properly sealed against water infiltration, eventually leading to spalling as the water froze and expanded. Later during construction of new on- and off-ramps in
3358-554: The interlinking of the silicates and aluminate components as well as their bonding to sand and gravel particles to form a solid mass. One illustrative conversion is the hydration of tricalcium silicate: The hydration (curing) of cement is irreversible. Fine and coarse aggregates make up the bulk of a concrete mixture. Sand , natural gravel, and crushed stone are used mainly for this purpose. Recycled aggregates (from construction, demolition, and excavation waste) are increasingly used as partial replacements for natural aggregates, while
3431-406: The making of mortar. In an English translation from 1397, it reads "lyme ... is a stone brent; by medlynge thereof with sonde and water sement is made". From the 14th century, the quality of mortar was again excellent, but only from the 17th century was pozzolana commonly added. The Canal du Midi was built using concrete in 1670. Perhaps the greatest step forward in the modern use of concrete
3504-531: The material. Mineral admixtures use recycled materials as concrete ingredients. Conspicuous materials include fly ash , a by-product of coal-fired power plants ; ground granulated blast furnace slag , a by-product of steelmaking ; and silica fume , a by-product of industrial electric arc furnaces . Structures employing Portland cement concrete usually include steel reinforcement because this type of concrete can be formulated with high compressive strength , but always has lower tensile strength . Therefore, it
3577-419: The mix, are being tested and used. These developments are ever growing in relevance to minimize the impacts caused by cement use, notorious for being one of the largest producers (at about 5 to 10%) of global greenhouse gas emissions . The use of alternative materials also is capable of lowering costs, improving concrete properties, and recycling wastes, the latest being relevant for circular economy aspects of
3650-478: The mixed concrete, often to a concrete mixer truck. Modern concrete is usually prepared as a viscous fluid, so that it may be poured into forms. The forms are containers that define the desired shape. Concrete formwork can be prepared in several ways, such as slip forming and steel plate construction . Alternatively, concrete can be mixed into dryer, non-fluid forms and used in factory settings to manufacture precast concrete products. Interruption in pouring
3723-441: The mixing of cement and water into a paste before combining these materials with aggregates can increase the compressive strength of the resulting concrete. The paste is generally mixed in a high-speed , shear-type mixer at a w/c (water to cement ratio) of 0.30 to 0.45 by mass. The cement paste premix may include admixtures such as accelerators or retarders, superplasticizers , pigments , or silica fume . The premixed paste
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#17328584223943796-441: The mixture to improve the physical properties of the wet mix, delay or accelerate the curing time, or otherwise change the finished material. Most concrete is poured with reinforcing materials (such as steel rebar ) embedded to provide tensile strength , yielding reinforced concrete . In the past, lime -based cement binders, such as lime putty, were often used but sometimes with other hydraulic cements , (water resistant) such as
3869-542: The paper sold at newsstands would be smaller, about 32 pages, and redesigned. This arrangement went into effect on March 30, 2009. In February 2014, the DMP announced its offices along with those of The News and the Free Press would move from the West Lafayette building to six floors in both the old and new sections of the former Federal Reserve building at 160 West Fort Street. The partnership expected to place signs on
3942-639: The pilot was provided with a primitive grid-like gun sight on his windshield. Deb Price 's debut column in The Detroit News in 1992 was the first syndicated national column in American mainstream media that spoke about gay life. On July 13, 1995, Newspaper Guild employees of the Detroit Free Press and The News along with pressmen, printers and Teamsters , working for the "Detroit Newspapers" distribution arm, went on strike . Approximately half of
4015-506: The properties or increase the performance envelope of the mix. Design-mix concrete can have very broad specifications that cannot be met with more basic nominal mixes, but the involvement of the engineer often increases the cost of the concrete mix. Concrete mixes are primarily divided into nominal mix, standard mix and design mix. Nominal mix ratios are given in volume of Cement : Sand : Aggregate {\displaystyle {\text{Cement : Sand : Aggregate}}} . Nominal mixes are
4088-468: The quality and nature of the product. Design mix ratios are decided by an engineer after analyzing the properties of the specific ingredients being used. Instead of using a 'nominal mix' of 1 part cement, 2 parts sand, and 4 parts aggregate (the second example from above), a civil engineer will custom-design a concrete mix to exactly meet the requirements of the site and conditions, setting material ratios and often designing an admixture package to fine-tune
4161-431: The request of his wife's father. Booth went on to construct Michigan's largest newspaper empire, founding the independent Booth Newspapers chain (now owned by S.I. Newhouse 's Advance Publications ) with his two brothers. The Detroit News building was erected in 1917. It was designed by architect Albert Kahn , who included a faux-stone concrete building with large street-level arches to admit light. The arches along
4234-576: The rival Free Press , combining business operations while keeping separate editorial staffs. The combined company is called the Detroit Media Partnership (DMP). The Free Press moved into The News building in 1998 and until May 7, 2006, the two published a single joint weekend edition. Today, The News is published Monday–Saturday, and has an editorial page in the Sunday Free Press . The Detroit News has an online version, including
4307-496: The staffers crossed the picket line before the unions ended their strike in February 1997. The strike was resolved in court three years later, with the journalists' union losing its unfair labor practices case on appeal. Still, the weakened unions remain active at the paper, representing a majority of the employees under their jurisdiction. August 3, 2005, Gannett announced that it would sell The News to MediaNews Group and purchase
4380-411: The strength of the concrete bonding to resist tension. The long-term durability of Roman concrete structures has been found to be due to its use of pyroclastic (volcanic) rock and ash, whereby the crystallization of strätlingite (a specific and complex calcium aluminosilicate hydrate) and the coalescence of this and similar calcium–aluminium-silicate–hydrate cementing binders helped give the concrete
4453-497: The surface of concrete for a decorative "exposed aggregate" finish, popular among landscape designers. Admixtures are materials in the form of powder or fluids that are added to the concrete to give it certain characteristics not obtainable with plain concrete mixes. Admixtures are defined as additions "made as the concrete mix is being prepared". The most common admixtures are retarders and accelerators. In normal use, admixture dosages are less than 5% by mass of cement and are added to
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#17328584223944526-535: The surfaces of the aggregate together, and is typically the most expensive component. Thus, variation in sizes of the aggregate reduces the cost of concrete. The aggregate is nearly always stronger than the binder, so its use does not negatively affect the strength of the concrete. Redistribution of aggregates after compaction often creates non-homogeneity due to the influence of vibration. This can lead to strength gradients. Decorative stones such as quartzite , small river stones or crushed glass are sometimes added to
4599-655: The various ingredients used to produce a given quantity of concrete, the cement is the most energetically expensive. Even complex and efficient kilns require 3.3 to 3.6 gigajoules of energy to produce a ton of clinker and then grind it into cement . Many kilns can be fueled with difficult-to-dispose-of wastes, the most common being used tires. The extremely high temperatures and long periods of time at those temperatures allows cement kilns to efficiently and completely burn even difficult-to-use fuels. The five major compounds of calcium silicates and aluminates comprising Portland cement range from 5 to 50% in weight. Combining water with
4672-439: The water content or adding chemical admixtures increases concrete workability. Excessive water leads to increased bleeding or segregation of aggregates (when the cement and aggregates start to separate), with the resulting concrete having reduced quality. Changes in gradation can also affect workability of the concrete, although a wide range of gradation can be used for various applications. An undesirable gradation can mean using
4745-515: Was Smeaton's Tower , built by British engineer John Smeaton in Devon , England, between 1756 and 1759. This third Eddystone Lighthouse pioneered the use of hydraulic lime in concrete, using pebbles and powdered brick as aggregate. A method for producing Portland cement was developed in England and patented by Joseph Aspdin in 1824. Aspdin chose the name for its similarity to Portland stone , which
4818-622: Was built largely of concrete, and the Pantheon has the world's largest unreinforced concrete dome. Concrete, as the Romans knew it, was a new and revolutionary material. Laid in the shape of arches , vaults and domes , it quickly hardened into a rigid mass, free from many of the internal thrusts and strains that troubled the builders of similar structures in stone or brick. Modern tests show that opus caementicium had as much compressive strength as modern Portland-cement concrete (c. 200 kg/cm [20 MPa; 2,800 psi]). However, due to
4891-444: Was completed in 1960. A crossing of the Saginaw River was formed by extending the highway north from the end of an eastern bypass of Saginaw originally built in 1950, crossing the river with a four-lane bascule bridge . The need for a replacement of the original structure became acute soon after it was completed, as the bridge opening frequently backed up traffic for several miles along Interstate 75, and many cargo ships crashed into
4964-602: Was greatly reduced. Low kiln temperatures in the burning of lime, lack of pozzolana, and poor mixing all contributed to a decline in the quality of concrete and mortar. From the 11th century, the increased use of stone in church and castle construction led to an increased demand for mortar. Quality began to improve in the 12th century through better grinding and sieving. Medieval lime mortars and concretes were non-hydraulic and were used for binding masonry, "hearting" (binding rubble masonry cores) and foundations. Bartholomaeus Anglicus in his De proprietatibus rerum (1240) describes
5037-448: Was made from quicklime , pozzolana and an aggregate of pumice . Its widespread use in many Roman structures , a key event in the history of architecture termed the Roman architectural revolution , freed Roman construction from the restrictions of stone and brick materials. It enabled revolutionary new designs in terms of both structural complexity and dimension. The Colosseum in Rome
5110-493: Was pioneered by the Nabatean traders who occupied and controlled a series of oases and developed a small empire in the regions of southern Syria and northern Jordan from the 4th century BC. They discovered the advantages of hydraulic lime , with some self-cementing properties, by 700 BC. They built kilns to supply mortar for the construction of rubble masonry houses, concrete floors, and underground waterproof cisterns . They kept
5183-614: Was quarried on the Isle of Portland in Dorset , England. His son William continued developments into the 1840s, earning him recognition for the development of "modern" Portland cement. Reinforced concrete was invented in 1849 by Joseph Monier . and the first reinforced concrete house was built by François Coignet in 1853. The first concrete reinforced bridge was designed and built by Joseph Monier in 1875. Prestressed concrete and post-tensioned concrete were pioneered by Eugène Freyssinet ,
5256-402: Was the ancestor of today's well-known news helicopter. In 1935 a single Lockheed Model 9 Orion was purchased and modified by Lockheed as a news camera plane for The Detroit News . To work in that role, a pod was built into the frontal leading edge of the right-wing about eight feet (2.4 m) out from the fuselage. This pod had a glass dome on the front and a mounted camera. To aim the camera
5329-615: Was used for construction in many ancient structures. Mayan concrete at the ruins of Uxmal (AD 850–925) is referenced in Incidents of Travel in the Yucatán by John L. Stephens . "The roof is flat and had been covered with cement". "The floors were cement, in some places hard, but, by long exposure, broken, and now crumbling under the feet." "But throughout the wall was solid, and consisting of large stones imbedded in mortar, almost as hard as rock." Small-scale production of concrete-like materials
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