Concrete in the Sydney opera house

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Introduction
Concrete in the Sydney opera house
Sydney house is a center of performing arts located in Sydney of the New South Wales. The
building holds numerous venues for performing hosting 1500 performances yearly. The building
occupies 1.8 hectares of land space and is 600 ft. tall and 394 ft. at widest point. Sydney house
contains shells of precast concrete composing of 75.2 meters radius sphere mainly used to form
the structure roof supported by ribs of precast concrete. In addition to shells of tiles and walls of
glass, the exterior of the building is covered with granite quarried panels. The treatments of the
interior is too conducted with concrete. The building hosts recording studio, restaurant and cafes,
bars, concert halls and theatre for drama.
Concrete used for construction purposes is a hard structural material comprising of sand
and gravel placed strongly together with cement and water. Sand and gravel are chemically inert
particles commonly known as aggregate. Previously, clay was the main substance that was being
used as a bonding material. Lime and gypsum were used as binders in developing a substance
that closely resembled the today’s modern concrete (Adalberth, 2014). Lime which is the
chemical calcium oxide, derived from limestone, chalk and oyster shells continued to be used as
the main agent for forming cement till the 1800s. A few years later, a mixture of limestone and
clay were burned and grounded together by Joseph Aspdin and the mixture was named Portland
cement which dominantly existed as the main agent of cementing applied in the production of
concrete.
Aggregates are commonly grouped in relation to their sizes generally as either fine which
possesses sizes ranging between 0.025mm to 6.5mm or course ranging between 6.5mm to

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38mm. aggregate materials must be free from unwanted mixtures such as soft particles and
vegetable matter since even slight contents of organic compounds of soil usually encourage
chemical reactions eventually affecting the concrete strength.
Methods of aggregate or cement production and the manifested qualities of the aggregate
or cement that is utilized in making concrete usually defines the characteristics of the concrete.
For example, the ratio of water to cement usually determines the character of an ordinary
structural concrete (Allen & Iano, 2011). The concrete is stronger when the content of water ratio
is equal or lower to that of cement. Presence of water is needful for simply ensuring that all
particles of the aggregate are surrounded by the paste of cement completely, aggregate spaces are
filled and the concrete achieves the desired viscosity which enables it to be poured and spread
efficiently and effectively. Another factor of concrete durability is also the cement amount in
comparison to the aggregate which is usually expressed three-part ration – cement to fine
aggregate to coarse aggregate. Relatively less aggregate is considered where a stronger concrete
is desired.
Concrete strength is usually measured in either pound per square inch or kilograms per
square centimeter of force required to crush a given sample of hardness or age. Environmental
factors possess great impacts on concrete particularly moisture and temperature. Unequal stresses
of the tensile are observed whenever a concrete is exposed to premature drying which can never
be resisted in an imperfect state of hardness (Zhang et al, 2014). Concrete is normally kept damp
for a while immediately upon pouring through a process called curing to slower the shrinkage
process which frequently occurs as it hardens. The strength of concrete is also affected by
adverse temperatures. With an aim of reducing the impacts resulting from this, calcium chloride
and related additives are added to the cement mixture. These additives accelerate the process of

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setting thereby, in turn, generating sufficient heat which counteracts low temperatures. Concretes
that are large and its proper coverage cannot be achieved are usually not poured in temperatures
of freezing.
Concrete hardened onto embedded metal commonly steel often referred to as either
reinforced concrete or ferroconcrete. The steel metal offers contribution to improving the tensile
strength of the concrete. Stresses such as the action of wind, earthquakes, strong vibrations or
forces triggering bending are not normally withstood by plain concretes hence making it not
suitable for most applications. The tensile strength of steel and the compressional strength of
concrete enables such reinforced concrete to withstand heavy stresses for a good duration of time
(Bergsdal et al, 2015). The ease of positioning steel closer to or exactly at the point where strong
stresses are expected is made possible through the fluidity of the concrete mix.
Prestressed concrete forms another innovation in the construction field. This type of
concrete is obtained through processes of pre-tensioning and post-tensioning. Lengths of steel
wire, cables and ropes are placed in an empty mold then stretched and anchored. After pouring of
the concrete and its settlement, anchors are released and as the steel is adjusting to its original
length, the concrete is compressed whereas, in the post-tensioning process, the steel is made to
run through ducts created in the concrete. After hardening of the concrete, anchoring of the steel
is done on the exterior of the member by use of a gripping device (Binici et al, 2012). The
transmitted intensity of compression is regulated through the application of a measured quantity
of stretching force to the steel.