Construction

Construction

A construction siteA construction site People have constructed buildings from ancient times as homes to provide shelter, monuments or places of worship. Earth, wood and stone have always been used as building materials. Bricks made from hardened clay were first used in the Middle East in about 3000 BC. Concrete is made by mixing sand, cement, water and gravel or other aggregates. Reinforced concrete dates from the late 1800s. It is often used in modern buildings, containing steel wires or rods to provide extra strength.


A pile-driver, a huge mechanical hammerA pile-driver, a huge mechanical hammer

Types of buildings

Buildings belong to one of two types. The first type has solid walls, called load-bearing walls, that support the floors and roof of the building. The second type has a framework of wood, steel or concrete that bears the weight of the building. Most buildings need foundations (a solid base) to prevent them from sinking into the ground or falling over. Foundations can be footings (underground walls), flat rafts, or underground supporting pillars, called piles, that are driven into the ground. An architect plans the design of the building, while engineers work out how to make it strong and safe.


Tower craneTower crane

Tower crane

Many machines are used in the construction of a tall building. A tower crane is a vital machine. It lifts heavy building materials, such as steel girders and concrete slabs (which form the building's floors and walls) to the upper floors.



Concrete mixer

Concrete mixing, pumping and spreadingConcrete mixing, pumping and spreadingThe drum of the concrete mixer spins round, mixing the ingredients—cement, sand and crushed rock (known as aggregate) and water—together. The concrete mixer keeps the concrete in liquid state by constantly turning the drum. The interior of the drum is fitted with a spiral blade. Rotating the drum in one direction, the concrete is pushed deeper into the drum while the concrete is being transported to the building site. This is called charging the mixer. Rotating the drum in the other direction forces, or discharges, the concrete out of the drum into chutes or into a concrete pump.


Bulldozer, digger and dumper truckBulldozer, digger and dumper truck

Bulldozer, digger
and dumper truck

A bulldozer uses its blade to push earth and rubble. A digger (also called a JCB or backhoe loader) can tear into the ground using the “teeth” on its loader bucket or backhoe. It scoops up the rubble and pours it into the back of a dumper truck. To dump its load, the truck body tips up, the tailgate at the back swings open and the rubble slides out.



Many construction vehicles have caterpillar tracks instead of wheels. They provide extra grip and spread the vehicle's weight, allowing it to move over muddy ground without slipping or sinking in.

Haul truckHaul truck

Consultant: Chris Oxlade

Timeline

  • c.3000 BC
    Concrete is first used by the ancient Egyptians, Chinese and Greeks.
  • 600 BC
    The first cranes are used in ancient Greece.
  • 1770
    British inventor Richard Edgeworth invents the caterpillar track.
  • 1867
    Reinforced concrete is invented by French gardener Joseph Monier.
  • 1884
    The first skyscraper, the Home Insurance Building, is built in Chicago, USA.
  • 1920
    The first dumper truck is built in Canada by Robert T. Mawhinney.
  • 1923
    The first bulldozer is constructed in the USA.

See also in Technology

See also in Science

The largest haul truck in the world, a type of dumper truck for use in big construction and mining projects, is the Caterpillar 797. It can carry a load weighing up to 363 tonnes. Its 4-m (13-ft) tyres are the the world's largest.

In the late 19th century, the word "bull-doser" meant someone who intimidated another person at gunpoint—that is, giving them a bull-sized "dose of medicine".  "Bulldozing" then changed to mean using brute force to get past any obstacle. In the 1930s it was applied to the newly invented vehicle.

Miniature bulldozers, for use in confined spaces, are known as calfdozers.

About 8500 km (5300 miles) of roads built by the Romans were made out of concrete. To help prevent the concrete from shrinking, Roman road-builders added horsehair to the mix.

Since the 1890s, some small ships have been built out of reinforced concrete.

Backhoe loaders were first used in the 1950s by British engineering company J.C. Bamforth—which is why these digging machines are also known as JCBs.

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