Ancient
History:
Cement
has been in usage by human beings throughout history; variants of the material
were used up to 12,000 years ago, with the earliest archaeological detection of
combined whitewashed floor made from burned limestone and clay found in
modern-day Turkey.
The
first fired clay bricks were established in the so-called Bountiful Crescent,
where it was discovered that lime could be produced from burnt limestone to
prepare mortar. Around 800BC, the Phoenicians used the information that a
mixture of burnt lime and volcanic ash, today called 'pozzolana', could be used
to produce hydraulic lime, that was not only stronger than anything previously
used, but also toughened under water.
The
Romans established new masonry procedures, with which they could erect grand
buildings with heavy foundations. One such improvement was "opus
caementitium", a type of concrete made of lime with aggregates of sand and
crushed rock. This was mostly used between masonry stones or bricks, aiding as
formwork. Other cements used crushed brick, tiles and ceramic pottery as
aggregates. The Roman architect and engineer Marcus Vitruvius Polllio systematically
described the knowledge and construction techniques of the time, which went on
to serve as the foundation of building methods for hundreds of years.
Famous
historical buildings made from concrete, still standing today, are the Coliseum
and Pantheon in Rome, and the Hagia Sophia in Istanbul.
The
Middle Ages
The
Middle Ages were a quiet time in the history of cement; any discoveries made
during this era remain unknown, although masons are known to have used
hydraulic cements to build structures such as fortresses and canals.
In
the guilds of the Middle Ages, awareness was a secret and was passed on to
students orally, not written down, whilst alchemists explored and examined
properties and reactivity of substances, often using coded language. Typical
mortars from this time comprised of lime and sand - concrete as we know it did
not yet exist.
The
Industrial Revolution in Europe in the late 18th century saw a outbreak of
new improvements in cement and concrete, with significant contributions made by
John Smeaton, who discovered that the hydraulicity of lime was directly related
to the limestone’s clay content, James Parker, Louis Vicat and Egor Cheliev.
The
Birth of Portland cement:
The
forerunner to modern-day cement was created in 1824 by Joseph Aspdin, a British
bricklayer and builder, who investigated with heating limestone and clay until
the mixture calcined, grinding it and then mixing it with water. Aspdin named
this Portland cement, after the famously strong building stone from the Isle of
Portland in Dorset, UK. His son, William Aspdin, made the first cement
containing alite (an impure form of tricalcium silicate).
In
1845, Isaac Johnson fired chalk and clay at much higher temperatures than the
Aspdins, at around 1400-1500oC,
which led to the mixture clinkering, and produced what is essentially
modern-day cement.
From
1850, the use of concrete made from Portland cement increased considerably. Projects
such as sculptures, small bridges and concrete pipes were typical applications
at the time and helped to increase its importance. Then followed large scale
sewage systems, such as in London and Paris, and the erection of metros and
subways increased demand. By the end of the 19th century, hollow concrete
blocks for housing construction became conventional.
The
advent of reinforced concretes began in the 1840s in France, starting a period
of invention, using strengthened columns, girders and so on to allow the building
of larger bridges, taller and larger buildings etc, and considerably decreased
the dominance of steel construction.
The
first cement standard for Portland cement was sanctioned in Germany in 1878, describing
the first test methods and minimum properties, with many other countries
following suit.
Cement
production and applications surged internationally at the turn of the century.
Since the 1900s, rotary kilns replaced the original vertical shaft kilns, as
they use radiative heat transfer, more efficient at higher temperatures, achieving
a uniform clinkering temperature and produces stronger cement. Gypsum is now
also added to the resulting mixture to control setting and ball mills are used
to grind clinker.
Other
advances in the last century include calcium aluminate cements for better
sulphate resistance, the blending of Rosendale (a natural hydraulic cement
produced in New York) and Portland cements to make a strong and fast-setting
cement in the USA, and the increased usage of cementitious materials to store
nuclear waste.
The
Future of Cement and Concrete
New
knowledge and inventions are continually evolving to advance the
sustainability, strength and applications of cement and concrete. Some advanced
products incorporate fibers and special aggregates to create roof tiles and
countertops, for example, whilst offsite manufacture is also gaining prominence
with the rise of digitalization and AI, which could reduce waste and improve
efficiency and on-site operational conditions. Cements and concretes are also
being developed which can absorb CO2 over
their lifetimes, reducing the carbon footprint of the building material.
Text contributions by Rainer
Nobis, author of "Illustrated History of Cement and Concrete"
SOURCE OF INFO &
ARTICLE CREDITS: https://www.worldcementassociation.org/about-cement/our-history
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