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Las Vegas

 

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Las Vegas
City
Downtown Las Vegas World Market Center The Strat Clark County Government Center Lou Ruvo Center for Brain Health Las Vegas Strip in Paradise and Winchester, outside city limits
Flag Seal
Etymology: from Spanish las vegas 'the meadows'
Nicknames:  "Vegas", "Sin City", "City of Lights", "The Gambling Capital of the World",[1] "The Entertainment Capital of the World", "Capital of Second Chances",[2] "The Marriage Capital of the World", "The Silver City", "America's Playground", "Hawaii's Ninth Island"[3][4]
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Las Vegas   Show map of Nevada
Coordinates: 36°10′2″N 115°8′55″W / 36.16722°N 115.14861°W / 36.16722; -115.14861
Country	United States
State	Nevada
County	Clark
Founded	May 15, 1905
Incorporated	March 16, 1911
Government
• Type	Council–manager
• Mayor	Shelley Berkley (D)
• Mayor Pro Tem	Brian Knudsen (D)
• City council	Members Brian Knudsen (D) Victoria Seaman (R) Olivia Diaz (D) Francis Allen-Palenske (R) Cedric Crear (D) Nancy Brune (D)
• City manager	Jorge Cervantes
Area [5]
• City	141.91 sq mi (367.53 km2)
• Land	141.85 sq mi (367.40 km2)
• Water	0.05 sq mi (0.14 km2)
• Urban	540 sq mi (1,400 km2)
• Metro	1,580 sq mi (4,100 km2)
Elevation	2,001 ft (610 m)
Population  (2020)
• City	641,903
• Rank	75th in North America 24th in the United States[6] 1st in Nevada
• Density	4,525.16/sq mi (1,747.17/km2)
• Urban	2,196,623 (US: 21st)
• Urban density	5,046.3/sq mi (1,948.4/km2)
• Metro [7]	2,265,461 (US: 29th)
Demonym	Las Vegan
GDP [8]
• Metro	$160.728 billion (2022)
Time zone	UTC−08:00 (PST)
• Summer (DST)	UTC−07:00 (PDT)
ZIP Codes	89044, 89054, 891xx
Area code(s)	702 and 725
FIPS code	32-40000
GNIS feature ID	847388
Website	lasvegasnevada.gov

Las Vegas,^[a] colloquially referred to as Vegas, is the most populous city in the U.S. state of Nevada and the seat of Clark County. The Las Vegas Valley metropolitan area is the largest within the greater Mojave Desert, and second-largest in the Southwestern United States. According to the United States Census Bureau, the city had 641,903 residents in 2020,^[9] with a metropolitan population of 2,227,053,^[10] making it the 24th-most populous city in the United States. Las Vegas is an internationally renowned major resort city, known primarily for its gambling, shopping, fine dining, entertainment, and nightlife, with most venues centered on downtown Las Vegas and more to the Las Vegas Strip just outside city limits in the unincorporated towns of Paradise and Winchester. The Las Vegas Valley serves as the leading financial, commercial, and cultural center in Nevada.

Las Vegas was settled in 1905 and officially incorporated in 1911.^[11] At the close of the 20th century, it was the most populated North American city founded within that century (a similar distinction was earned by Chicago in the 19th century). Population growth has accelerated since the 1960s and into the 21st century, and between 1990 and 2000 the population increased by 85.2%.

The city bills itself as the Entertainment Capital of the World, and is famous for its luxurious and large casino-hotels. With over 40.8 million visitors annually as of 2023,^[12] Las Vegas is one of the most visited cities in the United States, annually ranking as one of the world's most visited tourist destinations.^[13][14] It is the third most popular U.S. destination for business conventions^[15] and a global leader in the hospitality industry.^[16] The city's tolerance for numerous forms of adult entertainment has earned it the nickname "Sin City",^[17] and has made it a popular setting for literature, films, television programs, commercials and music videos.

In 1829, Mexican trader and explorer Antonio Armijo led a group consisting of 60 men and 100 mules along the Old Spanish Trail from modern day New Mexico to California. Along the way, the group stopped in what would become Las Vegas and noted its natural water sources, now referred to as the Las Vegas Springs, which supported extensive vegetation such as grasses and mesquite trees. The springs were a significant natural feature in the valley, with streams that supported a meadow ecosystem. This region served as the winter residence for the Southern Paiute people, who utilized the area's resources before moving to higher elevations during the summer months. The Spanish "las vegas" or "the meadows" (more precisely, lower land near a river) in English, was applied to describe the fertile lowlands near the springs. Over time, the name began to refer to the populated settlement.^[18][19][20]

Nomadic Paleo-Indians traveled to the Las Vegas area 10,000 years ago, leaving behind petroglyphs. Ancient Puebloan and Paiute tribes followed at least 2,000 years ago.^[21]

A young Mexican scout named Rafael Rivera is credited as the first non-Native American to encounter the valley, in 1829.^[22] Trader Antonio Armijo led a 60-man party along the Spanish Trail to Los Angeles, California, in 1829.^[23][24] In 1844, John C. Frémont arrived, and his writings helped lure pioneers to the area. Downtown Las Vegas's Fremont Street is named after him.

Eleven years later, members of the Church of Jesus Christ of Latter-day Saints chose Las Vegas as the site to build a fort halfway between Salt Lake City and Los Angeles, where they would travel to gather supplies. The fort was abandoned several years afterward. The remainder of this Old Mormon Fort can still be seen at the intersection of Las Vegas Boulevard and Washington Avenue.

Las Vegas was founded as a city in 1905, when 110 acres (45 ha) of land adjacent to the Union Pacific Railroad tracks were auctioned in what would become the downtown area. In 1911, Las Vegas was incorporated as a city.^[25]

The year 1931 was pivotal for Las Vegas. At that time, Nevada legalized casino gambling^[26] and reduced residency requirements for divorce to six weeks.^[27] This year also witnessed the beginning of construction of the tunnels of nearby Hoover Dam. The influx of construction workers and their families helped Las Vegas avoid economic calamity during the Great Depression. The construction work was completed in 1935.

In late 1941, Las Vegas Army Airfield was established. Renamed Nellis Air Force Base in 1950, it is now home to the United States Air Force Thunderbirds aerobatic team.^[28]

Following World War II, lavishly decorated hotels, gambling casinos, and big-name entertainment became synonymous with Las Vegas.

In 1951, nuclear weapons testing began at the Nevada Test Site, 65 miles (105 km) northwest of Las Vegas. During this time, the city was nicknamed the "Atomic City." Residents and visitors were able to witness the mushroom clouds (and were exposed to the fallout) until 1963 when the Partial Nuclear Test Ban Treaty required that nuclear tests be moved underground.^[29]

In 1955, the Moulin Rouge Hotel opened and became the first racially integrated casino-hotel in Las Vegas.

During the 1960s, corporations and business tycoons such as Howard Hughes were building and buying hotel-casino properties. Gambling was referred to as "gaming," which transitioned it into a legitimate business. Learning from Las Vegas, published during this era, asked architects to take inspiration from the city's highly decorated buildings, helping to start the postmodern architecture movement.

In 1995, the Fremont Street Experience opened in Las Vegas's downtown area. This canopied five-block area features 12.5 million LED lights and 550,000 watts of sound from dusk until midnight during shows held at the top of each hour.

Due to the realization of many revitalization efforts, 2012 was dubbed "The Year of Downtown." Projects worth hundreds of millions of dollars made their debut at this time, including the Smith Center for the Performing Arts, the Discovery Children's Museum, the Mob Museum, the Neon Museum, a new City Hall complex, and renovations for a new Zappos.com corporate headquarters in the old City Hall building.^[30][31]

Las Vegas is the county seat of Clark County, in a basin on the floor of the Mojave Desert,^[32] and is surrounded by mountain ranges. Much of the landscape is rocky and arid, with desert vegetation and wildlife. It can be subjected to torrential flash floods, although much has been done to mitigate the effects of flash floods through improved drainage systems.^[33]

The city's elevation is approximately 2,030 ft (620 m) above sea level, though the surrounding peaks reach elevations of over 10,000 feet (3,000 m) and act as barriers to the strong flow of moisture from the surrounding area. According to the United States Census Bureau, the city has an area of 135.86 sq mi (351.9 km²), of which 135.81 sq mi (351.7 km²) is land and 0.05 sq mi (0.13 km²) (0.03%) is water.

After Alaska and California, Nevada is the third most seismically active state in the U.S. It has been estimated by the United States Geological Survey (USGS) that over the next 50 years, there is a 10–20% chance of an M6.0 or greater earthquake occurring within 50 km (31 mi) of Las Vegas.^[34]

Within the city are many lawns, trees, and other greenery. Due to water resource issues, there has been a movement to encourage xeriscapes. Another part of conservation efforts is scheduled watering days for residential landscaping. A U.S. Environmental Protection Agency grant in 2008 funded a program that analyzed and forecast growth and environmental effects through 2019.^[35]

Las Vegas has a subtropical hot desert climate (Köppen climate classification: BWh, Trewartha climate classification BWhk), typical of the Mojave Desert in which it lies. This climate is typified by long, extremely hot summers; warm transitional seasons; and short winters with mild days and cool nights. There is abundant sunshine throughout the year, with an average of 310 sunny days and bright sunshine during 86% of all daylight hours.^[36][37] Rainfall is scarce, with an average of 4.2 in (110 mm) dispersed between roughly 26 total rainy days per year.^[38] Las Vegas is among the sunniest, driest, and least humid locations in North America, with exceptionally low dew points and humidity that sometimes remains below 10%.^[39]

The summer months of June through September are extremely hot, though moderated by the low humidity levels. July is the hottest month, with an average daytime high of 104.5 °F (40.3 °C). On average, 137 days per year reach or exceed 90 °F (32 °C), of which 78 days reach 100 °F (38 °C) and 10 days reach 110 °F (43 °C). During the peak intensity of summer, overnight lows frequently remain above 80 °F (27 °C), and occasionally above 85 °F (29 °C).^[36]

While most summer days are consistently hot, dry, and cloudless, the North American Monsoon sporadically interrupts this pattern and brings more cloud cover, thunderstorms, lightning, increased humidity, and brief spells of heavy rain. Potential monsoons affect Las Vegas between July and August. Summer in Las Vegas is marked by significant diurnal temperature variation. While less extreme than other parts of the state, nighttime lows in Las Vegas are often 30 °F (16.7 °C) or more lower than daytime highs.^[40] The average hottest night of the year is 90 °F (32 °C). The all-time record is at 95 °F (35 °C).^[36]

Las Vegas winters are relatively short, with typically mild daytime temperatures and chilly nights. Sunshine is abundant in all seasons. December is both the year's coolest and cloudiest month, with an average daytime high of 56.9 °F (13.8 °C) and sunshine occurring during 78% of its daylight hours. Winter evenings are defined by clear skies and swift drops in temperature after sunset, with overnight minima averaging around 40 °F (4.4 °C) in December and January. Owing to its elevation that ranges from 2,000 to 3,000 feet (610 to 910 m), Las Vegas experiences markedly cooler winters than other areas of the Mojave Desert and the adjacent Sonoran Desert that are closer to sea level. The city records freezing temperatures an average of 10 nights per winter. It is exceptionally rare for temperatures to reach or fall below 25 °F (−4 °C).^[36]

Most of the annual precipitation falls during the winter. February, the wettest month, averages only four days of measurable rain. The mountains immediately surrounding the Las Vegas Valley accumulate snow every winter, but significant accumulation within the city is rare, although moderate accumulations occur every few years. The most recent accumulations occurred on February 18, 2019, when parts of the city received about 1 to 2 inches (2.5 to 5.1 cm) of snow^[41] and on February 20 when the city received almost 0.5 inches (1.3 cm).^[42] Other recent significant snow accumulations occurred on December 25, 2015, and December 17, 2008.^[43] Unofficially, Las Vegas's largest snowfall on record was the 12 inches (30 cm) that fell in 1909.^[44] In recent times, ice days have not occurred, although 29 °F (−2 °C) was measured in 1963.^[36] On average the coldest day is 44 °F (7 °C).^[36]

The highest temperature officially observed for Las Vegas is 120 °F (48.9 °C), as measured at Harry Reid International Airport on July 7, 2024.^[36][45] The lowest temperature was 8 °F (−13 °C), recorded on two days: January 25, 1937, and January 13, 1963.^[36] The official record hot daily minimum is 95 °F (35 °C) on July 19, 2005, and July 1, 2013. The official record cold daily maximum is 28 °F (−2 °C) on January 8 and 21, 1937.^[36] July 2024 was the hottest month ever recorded in Las Vegas, with its highest recorded mean daily average temperature over the month of 99.9 °F (38 °C), its highest recorded mean daily maximum temperature of 111.5 °F (44 °C), and its highest recorded mean nightly minimum temperature of 88.3 °F (31 °C).^[46]

Due to concerns about climate change in the wake of a 2002 drought, daily water consumption has been reduced from 314 US gallons (1,190 L) per resident in 2003 to around 205 US gallons (780 L) in 2015.^[47]

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• Boulder City, incorporated
• Enterprise, unincorporated
• Henderson, incorporated
• Lone Mountain, unincorporated
• North Las Vegas, incorporated
• Paradise, unincorporated
• Spring Valley, unincorporated
• Summerlin South, unincorporated
• Sunrise Manor, unincorporated
• Whitney, unincorporated
• Winchester, unincorporated

• Downtown
• The Lakes
• Summerlin
• West Las Vegas

According to the 2020 United States census, the city of Las Vegas had 644,883 people living in 244,429 households. The racial composition of the City of Las Vegas was 49.2% white, 11.9% black, 1.1% American Indian or Alaska Native, 6.9% Asian, Hispanic or Latino residents of any race were 34.1% and 16.2% from two or more races. 40.8% were non-Hispanic white.^[53]

Approximately 5.8% of residents are under the age of five, 22.8% under the age of eighteen and 15.6% over 65 years old. Females are 50.0% of the total population.^[53]

⬤ Black

⬤ Asian

⬤ Hispanic

⬤ Other

From 2019 to 2023, Las Vegas had approximately 244,429 households, with an average of 2.63 persons per household. About 55.7% of housing units were owner-occupied, and the median value of owner-occupied housing was $395,300. Median gross rent during this period was $1,456 per month (in 2023 dollars).^[53]

The median household income in Las Vegas from 2019 to 2023 was $70,723, while the per capita income was $38,421 (in 2023 dollars). Approximately 14.2% of the population lived below the poverty line during the same period.^[53]

Residents over 25 years old with a high school diploma were 85.8% of the population with 27.3% having attained a bachelor's degree or higher.^[53]

About 33.0% of residents aged 5 and older speak a language other than English at home. 20.9% of residents are foreign-born.^[53]

The mean travel time to work for residents aged 16 and older was approximately 25.8 minutes between 2019 and 2023. The vast majority of households in Las Vegas are digitally connected, with 95.6% having a computer and 89.1% subscribing to broadband internet services .

According to demographer William H. Frey using data from the 2010 United States census, Las Vegas has the second-lowest level of black-white segregation of any of the 100 largest U.S. metropolitan areas after Tucson, Arizona.^[54]

According to the Las Vegas Asian Chamber of Commerce, Filipinos make up the largest ethnic population within Vegas. at 20% of the city's population.^[55] Native Hawaiians are also a major demographic in the city, with some Hawaiians and Las Vegas residents calling the city the "ninth island of Hawaii" due to the major influx of Hawaiians to Vegas.^[56]

According to a 2004 study, Las Vegas has one of the highest divorce rates.^[57][58] The city's high divorce rate is not wholly due to Las Vegans themselves getting divorced. Compared to other states, Nevada's nonrestrictive requirements for divorce result in many couples temporarily moving to Las Vegas in order to get divorced.^[59] Similarly, Nevada marriage requirements are equally lax resulting in one of the highest marriage rates of U.S. cities, with many licenses issued to people from outside the area (see Las Vegas weddings).^[59]

According to the 2010 Census, the city of Las Vegas had a population of 583,756. The city's racial composition had shifted slightly, with 47.91% of the population identifying as White alone (non-Hispanic), 10.63% as Black or African American alone (non-Hispanic), 0.41% as Native American or Alaska Native alone (non-Hispanic), 5.93% as Asian alone (non-Hispanic), 0.53% as Pacific Islander alone (non-Hispanic), 0.19% as Other Race alone (non-Hispanic), and 2.91% as Mixed race or Multiracial (non-Hispanic). Hispanic or Latino individuals of any race represented 31.50% of the population.^[51]

According to the 2000 census, Las Vegas had a population of 474,434 people. The racial makeup of the city was 58.52% White alone (non-Hispanic), 10.19% Black or African American alone (non-Hispanic), 0.51% Native American or Alaska Native alone (non-Hispanic), 4.72% Asian alone (non-Hispanic), 0.41% Pacific Islander alone (non-Hispanic), 0.14% Other Race alone (non-Hispanic), and 2.52% Mixed race or Multiracial (non-Hispanic). Hispanic or Latino individuals of any race made up 23.81% of the population.^[50]

The primary drivers of the Las Vegas economy are tourism, gaming, and conventions, which in turn feed the retail and restaurant industries.

The major attractions in Las Vegas are the casinos and the hotels, although in recent years other new attractions have begun to emerge.

Most casinos in the downtown area are on Fremont Street, with The STRAT Hotel, Casino & Skypod as one of the few exceptions. Fremont East, adjacent to the Fremont Street Experience, was granted variances to allow bars to be closer together, similar to the Gaslamp Quarter of San Diego, the goal being to attract a different demographic than the Strip attracts.

The Golden Gate Hotel and Casino, downtown along the Fremont Street Experience, is the oldest continuously operating hotel and casino in Las Vegas; it opened in 1906 as the Hotel Nevada.

In 1931, the Northern Club (now the La Bayou) opened.^[64][65] The most notable of the early casinos may have been Binion's Horseshoe (now Binion's Gambling Hall and Hotel) while it was run by Benny Binion.

Boyd Gaming has a major presence downtown operating the California Hotel & Casino, the Fremont Hotel & Casino, and the Main Street Casino. The Four Queens also operates downtown along the Fremont Street Experience.

Downtown casinos that have undergone major renovations and revitalization in recent years include the Golden Nugget Las Vegas, The D Las Vegas (formerly Fitzgerald's), the Downtown Grand Las Vegas (formerly Lady Luck), the El Cortez Hotel & Casino, and the Plaza Hotel & Casino.^[66]

In 2020, Circa Resort & Casino opened, becoming the first all-new hotel-casino to be built on Fremont Street since 1980.^[67]

The center of the gambling and entertainment industry is the Las Vegas Strip, outside the city limits in the surrounding unincorporated communities of Paradise and Winchester in Clark County. Some of the largest casinos and buildings are there.^[68]

The original Welcome to Fabulous Las Vegas sign

Gateway Arches

In 1929, the city installed a welcome arch over Fremont Street, at the corner of Main Street.^[69][70][71] It remained in place until 1931.^[72][73]

In 1959, the 25-foot-tall (7.6 m) Welcome to Fabulous Las Vegas sign was installed at the south end of the Las Vegas Strip. A replica welcome sign, standing nearly 16 feet (4.9 m) tall, was installed within city limits in 2002, at Las Vegas Boulevard and Fourth Street.^[74][75][76] The replica was destroyed in 2016, when a pickup truck crashed into it.^[77]

In 2018, the city approved plans for a new gateway landmark in the form of neon arches. It was built within city limits, in front of the Strat resort and north of Sahara Avenue.^[78] The project, built by YESCO, cost $6.5 million and stands 80 feet (24 m) high.^[79] Officially known as the Gateway Arches, the project was completed in 2020. The steel arches are blue during the day, and light up in a variety of colors at night.^[80]

Also located just north of the Strat are a pair of giant neon showgirls, initially added in 2018 as part of a $400,000 welcome display. The original showgirls were 25 feet (7.6 m) tall, but were replaced by new ones in 2022, rising 50 feet (15 m).^[81][82] The originals were refurbished following weather damage and installed at the Las Vegas Arts District.^[82][83]

When The Mirage opened in 1989, it started a trend of major resort development on the Las Vegas Strip outside of the city. This resulted in a drop in tourism in the downtown area, but many recent projects have increased the number of visitors to downtown.

An effort has been made by city officials to diversify the economy by attracting health-related, high-tech and other commercial interests. No state tax for individuals or corporations, as well as a lack of other forms of business-related taxes, have aided the success of these efforts.^[84]

The Fremont Street Experience was built in an effort to draw tourists back to the area and has been popular since its startup in 1995.

The city conducted a land-swap deal in 2000 with Lehman Brothers, acquiring 61 acres (25 ha) of property near downtown Las Vegas in exchange for 91 acres (37 ha) of the Las Vegas Technology Center.^[85] In 2004, Las Vegas Mayor Oscar Goodman announced that the area would become home to Symphony Park (originally called "Union Park"^[86]), a mixed-use development. The development is home to the Cleveland Clinic Lou Ruvo Center for Brain Health, The Smith Center for the Performing Arts, the Discovery Children's Museum, the Las Vegas Chamber of Commerce, and four residential projects totaling 600 residential units as of 2024.^[87]

In 2005, the World Market Center opened, consisting of three large buildings taking up 5,400,000 square feet (500,000 m²). Trade shows for the furniture and furnishing industries are held there semiannually.^[88]

Also nearby is the Las Vegas North Premium Outlets. With a second expansion, completed in May 2015, the mall currently offers 175 stores.^[89]

City offices moved to a new Las Vegas City Hall in February 2013 on downtown's Main Street. The former city hall building is now occupied by the corporate headquarters for the online retailer Zappos.com, which opened downtown in 2013. Zappos CEO Tony Hsieh took an interest in the urban area and contributed $350 million toward a revitalization effort called the Downtown Project.^[90][91] Projects funded include Las Vegas's first independent bookstore, The Writer's Block.^[92]

A number of new industries have moved to Las Vegas in recent decades. Zappos.com (now an Amazon subsidiary) was founded in San Francisco but by 2013 had moved its headquarters to downtown Las Vegas. Allegiant Air, a low-cost air carrier, launched in 1997 with its first hub at Harry Reid International Airport and headquarters in nearby Summerlin.

Planet 13 Holdings, a cannabis company, opened the world's largest cannabis dispensary in Las Vegas at 112,000 sq ft (10,400 m²).^[93][94]

A growing population means the Las Vegas Valley used 1.2 billion US gal (4.5 billion L) more water in 2014 than in 2011. Although water conservation efforts implemented in the wake of a 2002 drought have had some success, local water consumption remains 30 percent greater than in Los Angeles, and over three times that of San Francisco metropolitan area residents. The Southern Nevada Water Authority is building a $1.4 billion tunnel and pumping station to bring water from Lake Mead, has purchased water rights throughout Nevada, and has planned a controversial $3.2 billion pipeline across half the state. By law, the Las Vegas Water Service District "may deny any request for a water commitment or request for a water connection if the District has an inadequate supply of water." But limiting growth on the basis of an inadequate water supply has been unpopular with the casino and building industries.^[47]

The city is home to several museums, including the Neon Museum (the location for many of the historical signs from Las Vegas's mid-20th century heyday), The Mob Museum, the Las Vegas Natural History Museum, the Discovery Children's Museum, the Nevada State Museum and the Old Las Vegas Mormon Fort State Historic Park.

The city is home to an extensive Downtown Arts District, which hosts numerous galleries and events including the annual Las Vegas Film Festival. "First Friday" is a monthly celebration that includes arts, music, special presentations and food in a section of the city's downtown region called 18b, The Las Vegas Arts District.^[95] The festival extends into the Fremont East Entertainment District.^[96] The Thursday evening before First Friday is known in the arts district as "Preview Thursday," which highlights new gallery exhibitions throughout the district.^[97]

The Las Vegas Academy of International Studies, Performing and Visual Arts is a Grammy award-winning magnet school located in downtown Las Vegas. The Smith Center for the Performing Arts is downtown in Symphony Park and hosts various Broadway shows and other artistic performances.

Las Vegas has earned the moniker "Gambling Capital of the World," as it has the world's most land-based casinos.^[98] The city is also host to more AAA Five Diamond hotels than any other city in the world.^[99]

The Las Vegas Valley is the home of three major professional teams: the National Hockey League (NHL)'s Vegas Golden Knights, an expansion team that began play in the 2017–18 NHL season at T-Mobile Arena in nearby Paradise,^[100] the National Football League (NFL)'s Las Vegas Raiders, who relocated from Oakland, California, in 2020 and play at Allegiant Stadium in Paradise,^[101] and the Women's National Basketball Association (WNBA)'s Las Vegas Aces, who play at the Mandalay Bay Events Center. The Oakland Athletics of Major League Baseball (MLB) will move to Las Vegas by 2028.^[102][103]

Two minor league sports teams play in the Las Vegas area. The Las Vegas Aviators of the Pacific Coast League, the Triple-A farm club of the Athletics, play at Las Vegas Ballpark in nearby Summerlin.^[104] The Las Vegas Lights FC of the United Soccer League play in Cashman Field in Downtown Las Vegas.^[105][106]

The mixed martial arts promotion, Ultimate Fighting Championship (UFC), is headquartered in Las Vegas and also frequently holds fights in the city at T-Mobile Arena and at the UFC Apex training facility near the headquarters.^[107]

The city's parks and recreation department operates 78 regional, community, neighborhood, and pocket parks; four municipal swimming poools, 11 recreational centers, four active adult centers, eight cultural centers, six galleries, eleven dog parks, and four golf courses: Angel Park Golf Club, Desert Pines Golf Club, Durango Hills Golf Club, and the Las Vegas Municipal Golf Course.^[108]

It is also responsible for 123 playgrounds, 23 softball fields, 10 football fields, 44 soccer fields, 10 dog parks, six community centers, four senior centers, 109 skate parks, and six swimming pools.^[109]

The city of Las Vegas has a council–manager government.^[110] The mayor sits as a council member-at-large and presides over all city council meetings.^[110] If the mayor cannot preside over a city council meeting, then the Mayor pro tempore is the presiding officer of the meeting until the Mayor returns to his/her seat.^[111] The city manager is responsible for the administration and the day-to-day operations of all municipal services and city departments.^[112] The city manager maintains intergovernmental relationships with federal, state, county and other local governments.^[112]

Out of the 2,265,461 people in Clark County as of the 2020 Census, approximately 1,030,000 people live in unincorporated Clark County, and around 650,000 live in incorporated cities such as North Las Vegas, Henderson and Boulder City.^[113] Las Vegas and Clark County share a police department, the Las Vegas Metropolitan Police Department, which was formed after a 1973 merger of the Las Vegas Police Department and the Clark County Sheriff's Department.^[114] North Las Vegas, Henderson, Boulder City, Mesquite, UNLV and CCSD have their own police departments.^[115]

The federally-recognized Las Vegas Tribe of Paiute Indians (Southern Paiute: Nuvagantucimi) occupies a 31-acre (130,000 m²) reservation just north downtown between Interstate-15 and Main Street.^{[116][117][118]}

Downtown is the location of Lloyd D. George Federal District Courthouse^[119] and the Regional Justice Center,^[120] draws numerous companies providing bail, marriage, divorce, tax, incorporation and other legal services.

Primary and secondary public education is provided by the Clark County School District.^[127]

Public higher education is provided by the Nevada System of Higher Education (NSHE). Public institutions serving Las Vegas include the University of Nevada, Las Vegas (UNLV), the College of Southern Nevada (CSN), Nevada State University (NSU), and the Desert Research Institute (DRI).^[128]

UNLV is a public, land-grant, R1 research university and is home to the Kirk Kerkorian School of Medicine^[129] and the William S. Boyd School of Law, the only law school in Nevada.^[130] The university's campus is urban and located about two miles east of the Las Vegas strip. The Desert Research Institute's southern campus sits next to UNLV, while its northern campus is in Reno.^[131]

CSN, with campuses throughout Clark County,^[132] is a community college with one of the largest enrollments in the United States.^[133] In unincorporated Clark County, CSN's Charleston campus is home to the headquarters of Nevada Public Radio (KNPR), an NPR member station.^[134][135]

Touro University Nevada located in Henderson is a non-profit, private institution primarily focusing on medical education.^[136] Other institutions include a number of for-profit private schools (e.g., Le Cordon Bleu College of Culinary Arts, DeVry University, among others).^[137]

• Las Vegas Review-Journal, the area's largest daily newspaper, is published every morning. It was formed in 1909 but has roots back to 1905. It is the largest newspaper in Nevada and is ranked as one of the top 25 newspapers in the United States by circulation. In 2000, the Review-Journal installed the largest newspaper printing press in the world. It cost $40 million, weighs 910 tons and consists of 16 towers.^[138] Until his death in January 2021, the newspaper was owned by casino magnate Sheldon Adelson, who purchased it for $140 million in December 2015. In 2018, the Review-Journal received the Sigma Delta Chi Award from the Society of Professional Journalists for reporting the Oct 1 mass shooting on the Las Vegas Strip. In 2018 and 2022, Editor and Publisher magazine named the Review-Journal as one of 10 newspapers in the United States "doing it right."^[139][140]
• Las Vegas Sun, based in neighboring Henderson, is a daily newspaper. Although independently published, the print edition is distributed as a section inside the Review-Journal. The Sun is owned by the Greenspun family and is part of the Greenspun Media Group. It was founded independently in 1950 and in 1989 entered into a Joint Operating Agreement with the Review-Journal, which runs through 2040. The Sun has been described as "politically liberal."^[141] In 2009, the Sun was awarded a Pulitzer Prize for Public Service for coverage of the high death rate of construction workers on the Las Vegas Strip amid lax enforcement of regulations.^[142][143]
• Las Vegas Weekly, based in neighboring Henderson, is a free alternative weekly newspaper. It covers Las Vegas arts, entertainment, culture and news. Las Vegas Weekly was founded in 1992 and is published by the Greenspun Media Group.

Las Vegas is served by 10 full power television stations and 46 radio stations. The area is also served by two NOAA Weather Radio transmitters (162.55 MHz located in Boulder City and 162.40 MHz located on Potosi Mountain).

• Radio stations in Las Vegas
• Television stations in Las Vegas

• Desert Companion
• Las Vegas Weekly
• Luxury Las Vegas

RTC Transit is a public transportation system providing bus service throughout Las Vegas, Henderson, North Las Vegas and other areas of the valley. Inter-city bus service to and from Las Vegas is provided by Greyhound, BoltBus, Orange Belt Stages, Tufesa, and several smaller carriers.^[144]

Amtrak trains have not served Las Vegas since the service via the Desert Wind at Las Vegas station ceased in 1997, but Amtrak California operates Amtrak Thruway dedicated service between the city and its passenger rail stations in Bakersfield, California, as well as Los Angeles Union Station via Barstow.^[145]

High-speed rail project Brightline West began construction in 2024 to connect Brightline's Las Vegas station and the Rancho Cucamonga station in Greater Los Angeles.^[146]

The Las Vegas Monorail on the Strip was privately built, and upon bankruptcy taken over by the Las Vegas Convention and Visitors Authority.^[147]

Silver Rider Transit operates three routes within Las Vegas, offering connections to Laughlin,^[148] Mesquite,^[149] and Sandy Valley.^[150]

The Union Pacific Railroad is the only Class I railroad providing rail freight service to the city. Until 1997, the Amtrak Desert Wind train service ran through Las Vegas using the Union Pacific Railroad tracks.

In March 2010, the RTC launched bus rapid transit link in Las Vegas called the Strip & Downtown Express with limited stops and frequent service that connects downtown Las Vegas, the Strip and the Las Vegas Convention Center. Shortly after the launch, the RTC dropped the ACE name.^[151]

In 2016, 77.1 percent of working Las Vegas residents (those living in the city, but not necessarily working in the city) commuted by driving alone. About 11 percent commuted via carpool, 3.9 percent used public transportation, and 1.4 percent walked. About 2.3 percent of Las Vegas commuters used all other forms of transportation, including taxi, bicycle, and motorcycle. About 4.3% of working Las Vegas residents worked at home.^[152] In 2015, 10.2 percent of city of Las Vegas households were without a car, which increased slightly to 10.5 percent in 2016. The national average was 8.7 percent in 2016. Las Vegas averaged 1.63 cars per household in 2016, compared to a national average of 1.8 per household.

With some exceptions, including Las Vegas Boulevard, Boulder Highway (SR 582) and Rancho Drive (SR 599), the majority of surface streets in Las Vegas are laid out in a grid along Public Land Survey System section lines. Many are maintained by the Nevada Department of Transportation as state highways. The street numbering system is divided by the following streets:

• Westcliff Drive, US 95 Expressway, Fremont Street and Charleston Boulevard divide the north–south block numbers from west to east.
• Las Vegas Boulevard divides the east–west streets from the Las Vegas Strip to near the Stratosphere, then Main Street becomes the dividing line from the Stratosphere to the North Las Vegas border, after which the Goldfield Street alignment divides east and west.
• On the east side of Las Vegas, block numbers between Charleston Boulevard and Washington Avenue are different along Nellis Boulevard, which is the eastern border of the city limits.

Interstates 15, 11, and US 95 lead out of the city in four directions. Two major freeways – Interstate 15 and Interstate 11/U.S. Route 95 – cross in downtown Las Vegas. I-15 connects Las Vegas to Los Angeles, and heads northeast to and beyond Salt Lake City. I-11 goes northwest to the Las Vegas Paiute Indian Reservation and southeast to Henderson and to the Mike O'Callaghan–Pat Tillman Memorial Bridge, where from this point I-11 will eventually continue along US 93 towards Phoenix, Arizona. US 95 (and eventually I-11) connects the city to northwestern Nevada, including Carson City and Reno. US 93 splits from I-15 northeast of Las Vegas and goes north through the eastern part of the state, serving Ely and Wells. US 95 heads south from US 93 near Henderson through far eastern California. A partial beltway has been built, consisting of Interstate 215 on the south and Clark County 215 on the west and north. Other radial routes include Blue Diamond Road (SR 160) to Pahrump and Lake Mead Boulevard (SR 147) to Lake Mead.

East–west roads, north to south^[153]

North–south roads, west to east

Harry Reid International Airport handles international and domestic flights into the Las Vegas Valley. The airport also serves private aircraft and freight/cargo flights. Most general aviation traffic uses the smaller North Las Vegas Airport and Henderson Executive Airport.

• 2017 Las Vegas shooting
• List of films set in Las Vegas
• List of films shot in Las Vegas
• List of Las Vegas casinos that never opened
• List of mayors of Las Vegas
• List of television shows set in Las Vegas
• Radio stations in Las Vegas
• Television stations in Las Vegas

• Brigham, Jay. "Review: 'Reno, Las Vegas, and the Strip: A Tale of Three Cities'." Western Historical Quarterly 46.4 (2015): 529–530. JSTOR westhistquar.46.4.0529.
• Chung, Su Kim (2012). Las Vegas Then and Now, Holt: Thunder Bay Press, ISBN 978-1-60710-582-4
• Moehring, Eugene P. Resort City in the Sunbelt: Las Vegas, 1930–2000 (2000).
• Moehring, Eugene, "The Urban Impact: Towns and Cities in Nevada's History," Nevada Historical Society Quarterly 57 (Fall/Winter 2014): 177–200.
• Rowley, Rex J. Everyday Las Vegas: Local Life in a Tourist Town (2013)
• Stierli, Martino (2013). Las Vegas in the Rearview Mirror: The City in Theory, Photography, and Film, Los Angeles: Getty Publications, ISBN 978-1-60606-137-4
• Venturi, Robert (1972). Learning from Las Vegas: The Forgotten Symbolism of Architectural Form, Cambridge: MIT Press, ISBN 978-0-26272-006-9

• Official website
• "The Making of Las Vegas"^{[dead link‍]} (historical timeline)
• Geologic tour guide of the Las Vegas area from American Geological Institute
• National Weather Service Forecast – Las Vegas, NV

This article needs additional citations for verification. Please help improve this article by adding citations to reliable sources. Unsourced material may be challenged and removed. Find sources: "Concrete" – news · newspapers · books · scholar · JSTOR (July 2022) (Learn how and when to remove this message)

Concrete is a composite material composed of aggregate bonded together with a fluid cement that cures to a solid over time. Concrete is the second-most-used substance in the world after water,^[1] and is the most widely used building material.^[2] Concrete is the most manufactured material on Earth.^[3]

When aggregate is mixed with dry Portland cement and water, the mixture forms a fluid slurry that can be poured and molded into shape. The cement reacts with the water through a process called hydration^[4] that hardens it over several hours to form a solid matrix that binds the materials together into a durable stone-like material that has many uses.^[5] 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 that ambient temperature plays a significant role in how long it takes concrete to set. Often, additives (such as pozzolans or superplasticizers) are included in the mixture to improve the physical properties of the wet mix, delay or accelerate the curing time, or otherwise modify the finished material. Most structural concrete is poured with reinforcing materials (such as steel rebar) embedded to provide tensile strength, yielding reinforced concrete.

Before the invention of Portland cement in the early 1800s, lime-based cement binders, such as lime putty, were often used. The overwhelming majority of concretes are produced using Portland cement, but sometimes with other hydraulic cements, such as calcium aluminate cement.^[6][7] 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 is distinct from mortar.^[8] Whereas concrete is itself a building material, and contains both coarse (large) and fine (small) aggregate particles, mortar contains only fine aggregates and is mainly used as a bonding agent to hold bricks, tiles and other masonry units together.^[9] Grout is another material associated with concrete and cement. It also 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 the gaps to make up a solid mass in situ.

The word concrete comes from the Latin word "concretus" (meaning compact or condensed),^[10] 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.^[11][12] 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.^[13] Concrete was used for construction in many ancient structures.^[14]

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 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 the cisterns secret as these enabled the Nabataeans to thrive in the desert.^[15] Some of these structures survive to this day.^[15]

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.^[16]

The Romans used concrete extensively from 300 BC to AD 476.^[18] During the Roman Empire, Roman concrete (or opus caementicium) was made from quicklime, pozzolana and an aggregate of pumice.^[19] 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.^[20] The Colosseum in Rome was built largely of concrete, and the Pantheon has the world's largest unreinforced concrete dome.^[21]

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.^[22]

Modern tests show that opus caementicium had a similar compressive strength to modern Portland-cement concrete (c. 200 kg/cm² [20 MPa; 2,800 psi]).^[23] However, due to the absence of reinforcement, its tensile strength was far lower than modern reinforced concrete, and its mode of application also differed:^[24]

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 the strength of the concrete bonding to resist tension.^[25]

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 complex calcium aluminosilicate hydrate)^[26] and the coalescence of this and similar calcium–aluminium-silicate–hydrate cementing binders helped give the concrete a greater degree of fracture resistance even in seismically active environments.^[27] 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.^[28][29] The use of hot mixing and the presence of lime clasts have been proposed to give the concrete a self-healing ability, where cracks that form become filled with calcite that prevents the crack from spreading.^[30][31]

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 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 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.^[32]

The Canal du Midi was built using concrete in 1670.^[33]

Perhaps the greatest step forward in the modern use of concrete 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.^[34]

A method for producing Portland cement was developed in England and patented by Joseph Aspdin in 1824.^[35] Aspdin chose the name for its similarity to Portland stone, which 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.^[36]

Reinforced concrete was invented in 1849 by Joseph Monier.^[37] and the first reinforced concrete house was built by François Coignet^[38] in 1853. The first concrete reinforced bridge was designed and built by Joseph Monier in 1875.^[39]

Prestressed concrete and post-tensioned concrete were pioneered by Eugène Freyssinet, 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.^[40]

Concrete is an artificial composite material, comprising a matrix of cementitious binder (typically Portland cement paste or asphalt) and 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.^[41] 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 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 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 a concrete component—and become a part of the binder for the aggregate.^[42] Fly ash and slag can enhance some properties of concrete such as fresh properties and durability.^[42] 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 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 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.^[43] It consists of 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 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.^[44] The five major compounds of calcium silicates and aluminates comprising Portland cement range from 5 to 50% in weight.

Combining water with 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.^[45]

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.^[46] The hydration of cement involves many concurrent reactions. The process involves polymerization, the interlinking of the silicates and aluminate components as well as their bonding to sand and gravel particles to form a solid mass.^[47] One illustrative conversion is the hydration of tricalcium silicate:

Cement chemist notation:    C₃S + H → C-S-H + CH + heat

Standard notation:               Ca₃SiO₅ + H₂O → CaO・SiO₂・H₂O (gel) + Ca(OH)₂ + heat

Balanced:                             2 Ca₃SiO₅ + 7 H₂O → 3 CaO・2 SiO₂・4 H₂O (gel) + 3 Ca(OH)₂ + heat

                                             (approximately as the exact ratios of CaO, SiO₂ and H₂O in C-S-H can vary)^[47]

The hydration (curing) of cement is irreversible.^[48]

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 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 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.^[49] 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.^[50]

Decorative stones such as quartzite, small river stones or crushed glass are sometimes added to 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".^[51] 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 the concrete at the time of batching/mixing.^[52] (See § Production below.) The common types of admixtures^[53] are as follows:

• Accelerators speed up the hydration (hardening) of the concrete. Typical materials used are calcium chloride, calcium nitrate and sodium nitrate. However, use of chlorides may cause corrosion in steel reinforcing and is prohibited in some countries, so that nitrates may be favored, even though they are less effective than the chloride salt. Accelerating admixtures are especially useful for modifying the properties of concrete in cold weather.
• Air entraining agents add and entrain tiny air bubbles in the concrete, which reduces damage during freeze-thaw cycles, increasing durability. However, entrained air entails a tradeoff with strength, as each 1% of air may decrease compressive strength by 5%.^[54] If too much air becomes trapped in the concrete as a result of the mixing process, defoamers can be used to encourage the air bubble to agglomerate, rise to the surface of the wet concrete and then disperse.
• Bonding agents are used to create a bond between old and new concrete (typically a type of polymer) with wide temperature tolerance and corrosion resistance.
• Corrosion inhibitors are used to minimize the corrosion of steel and steel bars in concrete.
• Crystalline admixtures are typically added during batching of the concrete to lower permeability. The reaction takes place when exposed to water and un-hydrated cement particles to form insoluble needle-shaped crystals, which fill capillary pores and micro-cracks in the concrete to block pathways for water and waterborne contaminates. Concrete with crystalline admixture can expect to self-seal as constant exposure to water will continuously initiate crystallization to ensure permanent waterproof protection.
• Pigments can be used to change the color of concrete, for aesthetics.
• Plasticizers increase the workability of plastic, or "fresh", concrete, allowing it to be placed more easily, with less consolidating effort. A typical plasticizer is lignosulfonate. Plasticizers can be used to reduce the water content of a concrete while maintaining workability and are sometimes called water-reducers due to this use. Such treatment improves its strength and durability characteristics.
• Superplasticizers (also called high-range water-reducers) are a class of plasticizers that have fewer deleterious effects and can be used to increase workability more than is practical with traditional plasticizers. Superplasticizers are used to increase compressive strength. It increases the workability of the concrete and lowers the need for water content by 15–30%.
• Pumping aids improve pumpability, thicken the paste and reduce separation and bleeding.
• Retarders slow the hydration of concrete and are used in large or difficult pours where partial setting is undesirable before completion of the pour. Typical retarders include sugar, sodium gluconate, citric acid, and tartaric acid.^[55]

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),^[52] or as a replacement for Portland cement (blended cements).^[59] Products which incorporate limestone, fly ash, blast furnace slag, and other useful materials with pozzolanic properties into 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.^[60] 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 the construction industry, whose demand is ever growing with greater impacts on raw material extraction, waste generation and landfill practices.

• Fly ash: A by-product of coal-fired electric generating plants, it is used to partially replace Portland cement (by up to 60% by mass). The properties of fly ash depend on the type of coal burnt. In general, siliceous fly ash is pozzolanic, while calcareous fly ash has latent hydraulic properties.^[61]
• Ground granulated blast furnace slag (GGBFS or GGBS): A by-product of steel production is used to partially replace Portland cement (by up to 80% by mass). It has latent hydraulic properties.^[62]
• Silica fume: A by-product of the production of silicon and ferrosilicon alloys. Silica fume is similar to fly ash, but has a particle size 100 times smaller. This results in a higher surface-to-volume ratio and a much faster pozzolanic reaction. Silica fume is used to increase strength and durability of concrete, but generally requires the use of superplasticizers for workability.^[63]
• High reactivity metakaolin (HRM): Metakaolin produces concrete with strength and durability similar to concrete made with silica fume. While silica fume is usually dark gray or black in color, high-reactivity metakaolin is usually bright white in color, making it the preferred choice for architectural concrete where appearance is important.
• Carbon nanofibers can be added to concrete to enhance compressive strength and gain a higher Young's modulus, and also to improve the electrical properties required for strain monitoring, damage evaluation and self-health monitoring of concrete. Carbon fiber has many advantages in terms of mechanical and electrical properties (e.g., higher strength) and self-monitoring behavior due to the high tensile strength and high electrical conductivity.^[64]
• Carbon products have been added to make concrete electrically conductive, for deicing purposes.^[65]
• New research from Japan's University of Kitakyushu shows that a washed and dried recycled mix of used diapers can be an environmental solution to producing less landfill and using less sand in concrete production. A model home was built in Indonesia to test the strength and durability of the new diaper-cement composite.^[66]

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 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 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 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 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.^[67] 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 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, 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 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 $\displaystyle \textCement : Sand : Aggregate$. Nominal mixes are 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.^[68]

Thorough mixing is essential to produce uniform, high-quality concrete.

Separate paste mixing has shown that the mixing of cement and water into a paste before combining these materials with aggregates can increase the compressive strength of the resulting concrete.^[69] 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 is then blended with aggregates and any remaining batch water and final mixing is completed in conventional concrete mixing equipment.^[70]

Resonant acoustic mixing has also been found effective in producing ultra-high performance cementitious materials, as it produces a dense matrix with low porosity.^[71]

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 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.^[72][73] An undesirable gradation can mean using 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 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.^[74]

Workability can be measured by the concrete slump test, a simple measure of the plasticity of a fresh batch of concrete following the ASTM C 143 or EN 12350-2 test standards. Slump is normally measured by filling an "Abrams cone" with a sample from a fresh batch of concrete. The cone is placed with the wide end down onto a level, non-absorptive surface. It is then filled in three layers of equal volume, with each layer being tamped with a steel rod to consolidate the layer. When the cone is carefully lifted off, the enclosed material slumps a certain amount, owing to gravity. A relatively dry sample slumps very little, having a slump value of one or two inches (25 or 50 mm) out of one foot (300 mm). A relatively wet concrete sample may slump as much as eight inches. Workability can also be measured by the flow table test.

Slump can be increased by addition of chemical admixtures such as plasticizer or superplasticizer without changing the water-cement ratio.^[75] Some other admixtures, especially air-entraining admixture, can increase the slump of a mix.

High-flow concrete, like self-consolidating concrete, is tested by other flow-measuring methods. One of these methods includes placing the cone on the narrow end and observing how the mix flows through the cone while it is gradually lifted.

After mixing, concrete is a fluid and can be pumped to the location where needed.

Concrete must be kept moist during curing in order to achieve optimal strength and durability.^[76] During curing hydration occurs, allowing calcium-silicate hydrate (C-S-H) to form. Over 90% of a mix's final strength is typically reached within four weeks, with the remaining 10% achieved over years or even decades.^[77] The conversion of calcium hydroxide in the concrete into calcium carbonate from absorption of CO₂ over several decades further strengthens the concrete and makes it more resistant to damage. This carbonation reaction, however, lowers the pH of the cement pore solution and can corrode the reinforcement bars.

Hydration and hardening of concrete during the first three days is critical. Abnormally fast drying and shrinkage due to factors such as evaporation from wind during placement may lead to increased tensile stresses at a time when it has not yet gained sufficient strength, resulting in greater shrinkage cracking. The early strength of the concrete can be increased if it is kept damp during the curing process. Minimizing stress prior to curing minimizes cracking. High-early-strength concrete is designed to hydrate faster, often by increased use of cement that increases shrinkage and cracking. The strength of concrete changes (increases) for up to three years. It depends on cross-section dimension of elements and conditions of structure exploitation.^[50] Addition of short-cut polymer fibers can improve (reduce) shrinkage-induced stresses during curing and increase early and ultimate compression strength.^[78]

Properly curing concrete leads to increased strength and lower permeability and avoids cracking where the surface dries out prematurely. Care must also be taken to avoid freezing or overheating due to the exothermic setting of cement. Improper curing can cause spalling, reduced strength, poor abrasion resistance and cracking.

During the curing period, concrete is ideally maintained at controlled temperature and humidity. To ensure full hydration during curing, concrete slabs are often sprayed with "curing compounds" that create a water-retaining film over the concrete. Typical films are made of wax or related hydrophobic compounds. After the concrete is sufficiently cured, the film is allowed to abrade from the concrete through normal use.^[79]

Traditional conditions for curing involve spraying or ponding the concrete surface with water. The adjacent picture shows one of many ways to achieve this, ponding—submerging setting concrete in water and wrapping in plastic to prevent dehydration. Additional common curing methods include wet burlap and plastic sheeting covering the fresh concrete.

For higher-strength applications, accelerated curing techniques may be applied to the concrete. A common technique involves heating the poured concrete with steam, which serves to both keep it damp and raise the temperature so that the hydration process proceeds more quickly and more thoroughly.

Asphalt concrete (commonly called asphalt,^[80] blacktop, or pavement in North America, and tarmac, bitumen macadam, or rolled asphalt in the United Kingdom and Ireland) is a composite material commonly used to surface roads, parking lots, airports, as well as the core of embankment dams.^[81] Asphalt mixtures have been used in pavement construction since the beginning of the twentieth century.^[82] It consists of mineral aggregate bound together with asphalt, laid in layers, and compacted. The process was refined and enhanced by Belgian inventor and U.S. immigrant Edward De Smedt.^[83]

The terms asphalt (or asphaltic) concrete, bituminous asphalt concrete, and bituminous mixture are typically used only in engineering and construction documents, which define concrete as any composite material composed of mineral aggregate adhered with a binder. The abbreviation, AC, is sometimes used for asphalt concrete but can also denote asphalt content or asphalt cement, referring to the liquid asphalt portion of the composite material.

Graphene enhanced concretes are standard designs of concrete mixes, except that during the cement-mixing or production process, a small amount of chemically engineered graphene (typically < 0.5% by weight) is added.^[84][85] These enhanced graphene concretes are designed around the concrete application.

Bacteria such as Bacillus pasteurii, Bacillus pseudofirmus, Bacillus cohnii, Sporosarcina pasteuri, and Arthrobacter crystallopoietes increase the compression strength of concrete through their biomass. However some forms of bacteria can also be concrete-destroying.^[86] Bacillus sp. CT-5. can reduce corrosion of reinforcement in reinforced concrete by up to four times. Sporosarcina pasteurii reduces water and chloride permeability. B. pasteurii increases resistance to acid.^[87] Bacillus pasteurii and B. sphaericuscan induce calcium carbonate precipitation in the surface of cracks, adding compression strength.^[88]

Nanoconcrete (also spelled "nano concrete"' or "nano-concrete") is a class of materials that contains Portland cement particles that are no greater than 100 μm^[89] and particles of silica no greater than 500 μm, which fill voids that would otherwise occur in normal concrete, thereby substantially increasing the material's strength.^[90] It is widely used in foot and highway bridges where high flexural and compressive strength are indicated.^[88]

Pervious concrete is a mix of specially graded coarse aggregate, cement, water, and little-to-no fine aggregates. This concrete is also known as "no-fines" or porous concrete. Mixing the ingredients in a carefully controlled process creates a paste that coats and bonds the aggregate particles. The hardened concrete contains interconnected air voids totaling approximately 15 to 25 percent. Water runs through the voids in the pavement to the soil underneath. Air entrainment admixtures are often used in freeze-thaw climates to minimize the possibility of frost damage. Pervious concrete also permits rainwater to filter through roads and parking lots, to recharge aquifers, instead of contributing to runoff and flooding.^[91]

Polymer concretes are mixtures of aggregate and any of various polymers and may be reinforced. The cement is costlier than lime-based cements, but polymer concretes nevertheless have advantages; they have significant tensile strength even without reinforcement, and they are largely impervious to water. Polymer concretes are frequently used for the repair and construction of other applications, such as drains.

Plant fibers and particles can be used in a concrete mix or as a reinforcement.^[92][93][94] These materials can increase ductility but the lignocellulosic particles hydrolyze during concrete curing as a result of alkaline environment and elevated temperatures^[95][96][97] Such process, that is difficult to measure,^[98] can affect the properties of the resulting concrete.

Sulfur concrete is a special concrete that uses sulfur as a binder and does not require cement or water.

Volcanic concrete substitutes volcanic rock for the limestone that is burned to form clinker. It consumes a similar amount of energy, but does not directly emit carbon as a byproduct.^[99] Volcanic rock/ash are used as supplementary cementitious materials in concrete to improve the resistance to sulfate, chloride and alkali silica reaction due to pore refinement.^[100] Also, they are generally cost effective in comparison to other aggregates,^[101] good for semi and light weight concretes,^[101] and good for thermal and acoustic insulation.^[101]

Pyroclastic materials, such as pumice, scoria, and ashes are formed from cooling magma during explosive volcanic eruptions. They are used as supplementary cementitious materials (SCM) or as aggregates for cements and concretes.^[102] They have been extensively used since ancient times to produce materials for building applications. For example, pumice and other volcanic glasses were added as a natural pozzolanic material for mortars and plasters during the construction of the Villa San Marco in the Roman period (89 BC – 79 AD), which remain one of the best-preserved otium villae of the Bay of Naples in Italy.^[103]

Waste light is a form of polymer modified concrete. The specific polymer admixture allows the replacement of all the traditional aggregates (gravel, sand, stone) by any mixture of solid waste materials in the grain size of 3–10 mm to form a low-compressive-strength (3–20 N/mm²) product^[104] for road and building construction. One cubic meter of waste light concrete contains 1.1–1.3 m³ of shredded waste and no other aggregates.

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Recycled aggregate concretes are standard concrete mixes with the addition or substitution of natural aggregates with recycled aggregates sourced from construction and demolition wastes, disused pre-cast concretes or masonry. In most cases, recycled aggregate concrete results in higher water absorption levels by capillary action and permeation, which are the prominent determiners of the strength and durability of the resulting concrete. The increase in water absorption levels is mainly caused by the porous adhered mortar that exists in the recycled aggregates. Accordingly, recycled concrete aggregates that have been washed to reduce the quantity of mortar adhered to aggregates show lower water absorption levels compared to untreated recycled aggregates.

The quality of the recycled aggregate concrete is determined by several factors, including the size, the number of replacement cycles, and the moisture levels of the recycled aggregates. When the recycled concrete aggregates are crushed into coarser fractures, the mixed concrete shows better permeability levels, resulting in an overall increase in strength. In contrast, recycled masonry aggregates provide better qualities when crushed in finer fractures. With each generation of recycled concrete, the resulting compressive strength decreases.

Concrete has relatively high compressive strength, but much lower tensile strength.^[105] Therefore, it is usually reinforced with materials that are strong in tension (often steel). The elasticity of concrete is relatively constant at low stress levels but starts decreasing at higher stress levels as matrix cracking develops. Concrete has a very low coefficient of thermal expansion and shrinks as it matures. All concrete structures crack to some extent, due to shrinkage and tension. Concrete that is subjected to long-duration forces is prone to creep.

Tests can be performed to ensure that the properties of concrete correspond to specifications for the application.

The ingredients affect the strengths of the material. Concrete strength values are usually specified as the lower-bound compressive strength of either a cylindrical or cubic specimen as determined by standard test procedures.

The strengths of concrete is dictated by its function. Very low-strength—14 MPa (2,000 psi) or less—concrete may be used when the concrete must be lightweight.^[106] Lightweight concrete is often achieved by adding air, foams, or lightweight aggregates, with the side effect that the strength is reduced. For most routine uses, 20 to 32 MPa (2,900 to 4,600 psi) concrete is often used. 40 MPa (5,800 psi) concrete is readily commercially available as a more durable, although more expensive, option. Higher-strength concrete is often used for larger civil projects.^[107] Strengths above 40 MPa (5,800 psi) are often used for specific building elements. For example, the lower floor columns of high-rise concrete buildings may use concrete of 80 MPa (11,600 psi) or more, to keep the size of the columns small. Bridges may use long beams of high-strength concrete to lower the number of spans required.^[108][109] Occasionally, other structural needs may require high-strength concrete. If a structure must be very rigid, concrete of very high strength may be specified, even much stronger than is required to bear the service loads. Strengths as high as 130 MPa (18,900 psi) have been used commercially for these reasons.^[108]

The cement produced for making concrete accounts for about 8% of worldwide CO₂ emissions per year (compared to, e.g., global aviation at 1.9%).^[110][111] The two largest sources of CO₂ are produced by the cement manufacturing process, arising from (1) the decarbonation reaction of limestone in the cement kiln (T ≈ 950 °C), and (2) from the combustion of fossil fuel to reach the sintering temperature (T ≈ 1450 °C) of cement clinker in the kiln. The energy required for extracting, crushing, and mixing the raw materials (construction aggregates used in the concrete production, and also limestone and clay feeding the cement kiln) is lower. Energy requirement for transportation of ready-mix concrete is also lower because it is produced nearby the construction site from local resources, typically manufactured within 100 kilometers of the job site.^[112] The overall embodied energy of concrete at roughly 1 to 1.5 megajoules per kilogram is therefore lower than for many structural and construction materials.^[113]

Once in place, concrete offers a great energy efficiency over the lifetime of a building.^[114] Concrete walls leak air far less than those made of wood frames.^[115] Air leakage accounts for a large percentage of energy loss from a home. The thermal mass properties of concrete increase the efficiency of both residential and commercial buildings. By storing and releasing the energy needed for heating or cooling, concrete's thermal mass delivers year-round benefits by reducing temperature swings inside and minimizing heating and cooling costs.^[116] While insulation reduces energy loss through the building envelope, thermal mass uses walls to store and release energy. Modern concrete wall systems use both external insulation and thermal mass to create an energy-efficient building. Insulating concrete forms (ICFs) are hollow blocks or panels made of either insulating foam or rastra that are stacked to form the shape of the walls of a building and then filled with reinforced concrete to create the structure.

Concrete buildings are more resistant to fire than those constructed using steel frames, since concrete has lower heat conductivity than steel and can thus last longer under the same fire conditions. Concrete is sometimes used as a fire protection for steel frames, for the same effect as above. Concrete as a fire shield, for example Fondu fyre, can also be used in extreme environments like a missile launch pad.

Options for non-combustible construction include floors, ceilings and roofs made of cast-in-place and hollow-core precast concrete. For walls, concrete masonry technology and Insulating Concrete Forms (ICFs) are additional options. ICFs are hollow blocks or panels made of fireproof insulating foam that are stacked to form the shape of the walls of a building and then filled with reinforced concrete to create the structure.

Concrete also provides good resistance against externally applied forces such as high winds, hurricanes, and tornadoes owing to its lateral stiffness, which results in minimal horizontal movement. However, this stiffness can work against certain types of concrete structures, particularly where a relatively higher flexing structure is required to resist more extreme forces.

As discussed above, concrete is very strong in compression, but weak in tension. Larger earthquakes can generate very large shear loads on structures. These shear loads subject the structure to both tensile and compressional loads. Concrete structures without reinforcement, like other unreinforced masonry structures, can fail during severe earthquake shaking. Unreinforced masonry structures constitute one of the largest earthquake risks globally.^[117] These risks can be reduced through seismic retrofitting of at-risk buildings, (e.g. school buildings in Istanbul, Turkey).^[118]

Concrete is one of the most durable building materials. It provides superior fire resistance compared with wooden construction and gains strength over time. Structures made of concrete can have a long service life.^[119] Concrete is used more than any other artificial material in the world.^[120] As of 2006, about 7.5 billion cubic meters of concrete are made each year, more than one cubic meter for every person on Earth.^[121]

The use of reinforcement, in the form of iron was introduced in the 1850s by French industrialist François Coignet, and it was not until the 1880s that German civil engineer G. A. Wayss used steel as reinforcement. Concrete is a relatively brittle material that is strong under compression but less in tension. Plain, unreinforced concrete is unsuitable for many structures as it is relatively poor at withstanding stresses induced by vibrations, wind loading, and so on. Hence, to increase its overall strength, steel rods, wires, mesh or cables can be embedded in concrete before it is set. This reinforcement, often known as rebar, resists tensile forces.^[123]

Reinforced concrete (RC) is a versatile composite and one of the most widely used materials in modern construction. It is made up of different constituent materials with very different properties that complement each other. In the case of reinforced concrete, the component materials are almost always concrete and steel. These two materials form a strong bond together and are able to resist a variety of applied forces, effectively acting as a single structural element.^[124]

Reinforced concrete can be precast or cast-in-place (in situ) concrete, and is used in a wide range of applications such as; slab, wall, beam, column, foundation, and frame construction. Reinforcement is generally placed in areas of the concrete that are likely to be subject to tension, such as the lower portion of beams. Usually, there is a minimum of 50 mm cover, both above and below the steel reinforcement, to resist spalling and corrosion which can lead to structural instability.^[123] Other types of non-steel reinforcement, such as Fibre-reinforced concretes are used for specialized applications, predominately as a means of controlling cracking.^[124]

Precast concrete is concrete which is cast in one place for use elsewhere and is a mobile material. The largest part of precast production is carried out in the works of specialist suppliers, although in some instances, due to economic and geographical factors, scale of product or difficulty of access, the elements are cast on or adjacent to the construction site.^[125] Precasting offers considerable advantages because it is carried out in a controlled environment, protected from the elements, but the downside of this is the contribution to greenhouse gas emission from transportation to the construction site.^[124]

Advantages to be achieved by employing precast concrete:^[125]

• Preferred dimension schemes exist, with elements of tried and tested designs available from a catalogue.
• Major savings in time result from manufacture of structural elements apart from the series of events which determine overall duration of the construction, known by planning engineers as the 'critical path'.
• Availability of Laboratory facilities capable of the required control tests, many being certified for specific testing in accordance with National Standards.
• Equipment with capability suited to specific types of production such as stressing beds with appropriate capacity, moulds and machinery dedicated to particular products.
• High-quality finishes achieved direct from the mould eliminate the need for interior decoration and ensure low maintenance costs.

Due to cement's exothermic chemical reaction while setting up, large concrete structures such as dams, navigation locks, large mat foundations, and large breakwaters generate excessive heat during hydration and associated expansion. To mitigate these effects, post-cooling^[126] is commonly applied during construction. An early example at Hoover Dam used a network of pipes between vertical concrete placements to circulate cooling water during the curing process to avoid damaging overheating. Similar systems are still used; depending on volume of the pour, the concrete mix used, and ambient air temperature, the cooling process may last for many months after the concrete is placed. Various methods also are used to pre-cool the concrete mix in mass concrete structures.^[126]

Another approach to mass concrete structures that minimizes cement's thermal by-product is the use of roller-compacted concrete, which uses a dry mix which has a much lower cooling requirement than conventional wet placement. It is deposited in thick layers as a semi-dry material then roller compacted into a dense, strong mass.

Raw concrete surfaces tend to be porous and have a relatively uninteresting appearance. Many finishes can be applied to improve the appearance and preserve the surface against staining, water penetration, and freezing.

Examples of improved appearance include stamped concrete where the wet concrete has a pattern impressed on the surface, to give a paved, cobbled or brick-like effect, and may be accompanied with coloration. Another popular effect for flooring and table tops is polished concrete where the concrete is polished optically flat with diamond abrasives and sealed with polymers or other sealants.

Other finishes can be achieved with chiseling, or more conventional techniques such as painting or covering it with other materials.

The proper treatment of the surface of concrete, and therefore its characteristics, is an important stage in the construction and renovation of architectural structures.^[127]

Prestressed concrete is a form of reinforced concrete that builds in compressive stresses during construction to oppose tensile stresses experienced in use. This can greatly reduce the weight of beams or slabs, by better distributing the stresses in the structure to make optimal use of the reinforcement. For example, a horizontal beam tends to sag. Prestressed reinforcement along the bottom of the beam counteracts this. In pre-tensioned concrete, the prestressing is achieved by using steel or polymer tendons or bars that are subjected to a tensile force prior to casting, or for post-tensioned concrete, after casting.

There are two different systems being used:^[124]

• Pretensioned concrete is almost always precast, and contains steel wires (tendons) that are held in tension while the concrete is placed and sets around them.
• Post-tensioned concrete has ducts through it. After the concrete has gained strength, tendons are pulled through the ducts and stressed. The ducts are then filled with grout. Bridges built in this way have experienced considerable corrosion of the tendons, so external post-tensioning may now be used in which the tendons run along the outer surface of the concrete.

More than 55,000 miles (89,000 km) of highways in the United States are paved with this material. Reinforced concrete, prestressed concrete and precast concrete are the most widely used types of concrete functional extensions in modern days. For more information see Brutalist architecture.

Once mixed, concrete is typically transported to the place where it is intended to become a structural item. Various methods of transportation and placement are used depending on the distances involve, quantity needed, and other details of application. Large amounts are often transported by truck, poured free under gravity or through a tremie, or pumped through a pipe. Smaller amounts may be carried in a skip (a metal container which can be tilted or opened to release the contents, usually transported by crane or hoist), or wheelbarrow, or carried in toggle bags for manual placement underwater.

Extreme weather conditions (extreme heat or cold; windy conditions, and humidity variations) can significantly alter the quality of concrete. Many precautions are observed in cold weather placement.^[128] Low temperatures significantly slow the chemical reactions involved in hydration of cement, thus affecting the strength development. Preventing freezing is the most important precaution, as formation of ice crystals can cause damage to the crystalline structure of the hydrated cement paste. If the surface of the concrete pour is insulated from the outside temperatures, the heat of hydration will prevent freezing.

The American Concrete Institute (ACI) definition of cold weather placement, ACI 306,^[129] is:

• A period when for more than three successive days the average daily air temperature drops below 40 °F (~ 4.5 °C), and
• Temperature stays below 50 °F (10 °C) for more than one-half of any 24-hour period.

In Canada, where temperatures tend to be much lower during the cold season, the following criteria are used by CSA A23.1:

• When the air temperature is ≤ 5 °C, and
• When there is a probability that the temperature may fall below 5 °C within 24 hours of placing the concrete.

The minimum strength before exposing concrete to extreme cold is 500 psi (3.4 MPa). CSA A 23.1 specified a compressive strength of 7.0 MPa to be considered safe for exposure to freezing.

Concrete may be placed and cured underwater. Care must be taken in the placement method to prevent washing out the cement. Underwater placement methods include the tremie, pumping, skip placement, manual placement using toggle bags, and bagwork.^[130]

A tremie is a vertical, or near-vertical, pipe with a hopper at the top used to pour concrete underwater in a way that avoids washout of cement from the mix due to turbulent water contact with the concrete while it is flowing. This produces a more reliable strength of the product. The toggle bag method is generally used for placing small quantities and for repairs. Wet concrete is loaded into a reusable canvas bag and squeezed out at the required place by the diver. Care must be taken to avoid washout of the cement and fines.

Underwater bagwork is the manual placement by divers of woven cloth bags containing dry mix, followed by piercing the bags with steel rebar pins to tie the bags together after every two or three layers, and create a path for hydration to induce curing, which can typically take about 6 to 12 hours for initial hardening and full hardening by the next day. Bagwork concrete will generally reach full strength within 28 days. Each bag must be pierced by at least one, and preferably up to four pins. Bagwork is a simple and convenient method of underwater concrete placement which does not require pumps, plant, or formwork, and which can minimise environmental effects from dispersing cement in the water. Prefilled bags are available, which are sealed to prevent premature hydration if stored in suitable dry conditions. The bags may be biodegradable.^[131]

Grouted aggregate is an alternative method of forming a concrete mass underwater, where the forms are filled with coarse aggregate and the voids then completely filled from the bottom by displacing the water with pumped grout.^[130]

Concrete roads are more fuel efficient to drive on,^[132] more reflective and last significantly longer than other paving surfaces, yet have a much smaller market share than other paving solutions. Modern-paving methods and design practices have changed the economics of concrete paving, so that a well-designed and placed concrete pavement will be less expensive on initial costs and significantly less expensive over the life cycle. Another major benefit is that pervious concrete can be used, which eliminates the need to place storm drains near the road, and reducing the need for slightly sloped roadway to help rainwater to run off. No longer requiring discarding rainwater through use of drains also means that less electricity is needed (more pumping is otherwise needed in the water-distribution system), and no rainwater gets polluted as it no longer mixes with polluted water. Rather, it is immediately absorbed by the ground.^{[citation needed]}

Cement molded into a forest of tubular structures can be 5.6 times more resistant to cracking/failure than standard concrete. The approach mimics mammalian cortical bone that features elliptical, hollow osteons suspended in an organic matrix, connected by relatively weak "cement lines". Cement lines provide a preferable in-plane crack path. This design fails via a "stepwise toughening mechanism". Cracks are contained within the tube, reducing spreading, by dissipating energy at each tube/step.^[133]

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The manufacture and use of concrete produce a wide range of environmental, economic and social impacts.

Grinding of concrete can produce hazardous dust. Exposure to cement dust can lead to issues such as silicosis, kidney disease, skin irritation and similar effects. The U.S. National Institute for Occupational Safety and Health in the United States recommends attaching local exhaust ventilation shrouds to electric concrete grinders to control the spread of this dust. In addition, the Occupational Safety and Health Administration (OSHA) has placed more stringent regulations on companies whose workers regularly come into contact with silica dust. An updated silica rule, which OSHA put into effect 23 September 2017 for construction companies, restricted the amount of breathable crystalline silica workers could legally come into contact with to 50 micro grams per cubic meter of air per 8-hour workday. That same rule went into effect 23 June 2018 for general industry, hydraulic fracturing and maritime. That deadline was extended to 23 June 2021 for engineering controls in the hydraulic fracturing industry. Companies which fail to meet the tightened safety regulations can face financial charges and extensive penalties. The presence of some substances in concrete, including useful and unwanted additives, can cause health concerns due to toxicity and radioactivity. Fresh concrete (before curing is complete) is highly alkaline and must be handled with proper protective equipment.

A major component of concrete is cement, a fine powder used mainly to bind sand and coarser aggregates together in concrete. Although a variety of cement types exist, the most common is "Portland cement", which is produced by mixing clinker with smaller quantities of other additives such as gypsum and ground limestone. The production of clinker, the main constituent of cement, is responsible for the bulk of the sector's greenhouse gas emissions, including both energy intensity and process emissions.^[134]

The cement industry is one of the three primary producers of carbon dioxide, a major greenhouse gas – the other two being energy production and transportation industries. On average, every tonne of cement produced releases one tonne of CO₂ into the atmosphere. Pioneer cement manufacturers have claimed to reach lower carbon intensities, with 590 kg of CO₂eq per tonne of cement produced.^[135] The emissions are due to combustion and calcination processes,^[136] which roughly account for 40% and 60% of the greenhouse gases, respectively. Considering that cement is only a fraction of the constituents of concrete, it is estimated that a tonne of concrete is responsible for emitting about 100–200 kg of CO₂.^[137][138] Every year more than 10 billion tonnes of concrete are used worldwide.^[138] In the coming years, large quantities of concrete will continue to be used, and the mitigation of CO₂ emissions from the sector will be even more critical.

Concrete is used to create hard surfaces that contribute to surface runoff, which can cause heavy soil erosion, water pollution, and flooding, but conversely can be used to divert, dam, and control flooding. Concrete dust released by building demolition and natural disasters can be a major source of dangerous air pollution. Concrete is a contributor to the urban heat island effect, though less so than asphalt.

Reducing the cement clinker content might have positive effects on the environmental life-cycle assessment of concrete. Some research work on reducing the cement clinker content in concrete has already been carried out. However, there exist different research strategies. Often replacement of some clinker for large amounts of slag or fly ash was investigated based on conventional concrete technology. This could lead to a waste of scarce raw materials such as slag and fly ash. The aim of other research activities is the efficient use of cement and reactive materials like slag and fly ash in concrete based on a modified mix design approach.^[139]

The embodied carbon of a precast concrete facade can be reduced by 50% when using the presented fiber reinforced high performance concrete in place of typical reinforced concrete cladding.^[140] Studies have been conducted about commercialization of low-carbon concretes. Life cycle assessment (LCA) of low-carbon concrete was investigated according to the ground granulated blast-furnace slag (GGBS) and fly ash (FA) replacement ratios. Global warming potential (GWP) of GGBS decreased by 1.1 kg CO₂ eq/m³, while FA decreased by 17.3 kg CO₂ eq/m³ when the mineral admixture replacement ratio was increased by 10%. This study also compared the compressive strength properties of binary blended low-carbon concrete according to the replacement ratios, and the applicable range of mixing proportions was derived.^[141]

High-performance building materials will be particularly important for enhancing resilience, including for flood defenses and critical-infrastructure protection.^[142] Risks to infrastructure and cities posed by extreme weather events are especially serious for those places exposed to flood and hurricane damage, but also where residents need protection from extreme summer temperatures. Traditional concrete can come under strain when exposed to humidity and higher concentrations of atmospheric CO₂. While concrete is likely to remain important in applications where the environment is challenging, novel, smarter and more adaptable materials are also needed.^[138][143]

There have been concerns about the recycling of painted concrete due to possible lead content. Studies have indicated that recycled concrete exhibits lower strength and durability compared to concrete produced using natural aggregates.^{[148][149][150][151]} This deficiency can be addressed by incorporating supplementary materials such as fly ash into the mixture.^[152]

The world record for the largest concrete pour in a single project is the Three Gorges Dam in Hubei Province, China by the Three Gorges Corporation. The amount of concrete used in the construction of the dam is estimated at 16 million cubic meters over 17 years. The previous record was 12.3 million cubic meters held by Itaipu hydropower station in Brazil.^{[153][154][155]}

The world record for concrete pumping was set on 7 August 2009 during the construction of the Parbati Hydroelectric Project, near the village of Suind, Himachal Pradesh, India, when the concrete mix was pumped through a vertical height of 715 m (2,346 ft).^[156][157]

The Polavaram dam works in Andhra Pradesh on 6 January 2019 entered the Guinness World Records by pouring 32,100 cubic metres of concrete in 24 hours.^[158] The world record for the largest continuously poured concrete raft was achieved in August 2007 in Abu Dhabi by contracting firm Al Habtoor-CCC Joint Venture and the concrete supplier is Unibeton Ready Mix.^[159][160] The pour (a part of the foundation for the Abu Dhabi's Landmark Tower) was 16,000 cubic meters of concrete poured within a two-day period.^[161] The previous record, 13,200 cubic meters poured in 54 hours despite a severe tropical storm requiring the site to be covered with tarpaulins to allow work to continue, was achieved in 1992 by joint Japanese and South Korean consortiums Hazama Corporation and the Samsung C&T Corporation for the construction of the Petronas Towers in Kuala Lumpur, Malaysia.^[162]

The world record for largest continuously poured concrete floor was completed 8 November 1997, in Louisville, Kentucky by design-build firm EXXCEL Project Management. The monolithic placement consisted of 225,000 square feet (20,900 m²) of concrete placed in 30 hours, finished to a flatness tolerance of F_F 54.60 and a levelness tolerance of F_L 43.83. This surpassed the previous record by 50% in total volume and 7.5% in total area.^[163][164]

The record for the largest continuously placed underwater concrete pour was completed 18 October 2010, in New Orleans, Louisiana by contractor C. J. Mahan Construction Company, LLC of Grove City, Ohio. The placement consisted of 10,251 cubic yards of concrete placed in 58.5 hours using two concrete pumps and two dedicated concrete batch plants. Upon curing, this placement allows the 50,180-square-foot (4,662 m²) cofferdam to be dewatered approximately 26 feet (7.9 m) below sea level to allow the construction of the Inner Harbor Navigation Canal Sill & Monolith Project to be completed in the dry.^[165]

Concrete is used as an artistic medium.^{[citation needed]} Its appearance is also imitated in other media: for example Congolese artist Sardoine Mia creates canvases that look like concrete surfaces.^[166]

• Concrete leveling – Process to level concrete by levelling its underlying foundation
• Concrete mixer – Device that combines cement, aggregate, and water to form concrete
• Concrete masonry unit – Standard-sized block used in constructionPages displaying short descriptions of redirect targets
• Concrete plant – Equipment that combines various ingredients to form concrete
• Eurocode 2: Design of concrete structures
• Heavy metals – Loosely defined subset of elements that exhibit metallic properties
• Hempcrete – Biocomposite material used for construction and insulation
• Particulates – Microscopic solid or liquid matter suspended in the Earth's atmosphere
• Schmidt hammer – Type of measuring instrument
• Syncrete – Synthetic form of concrete
• Thermal integrity profiling – Method used to test concrete