History of Concrete 5
Egyptianswere among the very early users of cement, to be succinct 5000 yearsago, and were using concrete in the construction of the pyramids.This is where they mixed straw and mud to create bricks and used limeand gypsum to make mortars. Between 300BC and 476 AD, Romans wereusing materials similar to modern cement to make many of thearchitectural wonders, such as the Pantheon and the Colosseum(Concrete Networks, 2014). Additions to the Romans cement includedanimal products to attain particular goals. Startlingly after thecollapse of the Roman Empire in 476 AD, the art of using concrete wastemporarily lost. The techniques of making pozzolan cement were lostuntil the discovery of manuscripts detaining those methods in 1414,where the interest in building with concrete was revived. In 1678,Moxon Joseph wrote about the inherent fire in the heated lime whichemerged with the addition of water (Concrete Networks, 2014).
In1756, a British Engineer Smeaton John discovered hydraulic cement viaconstant testing of mortar in both salty and fresh water. In 1779,Higgins Bry was given a patent for stucco (hydraulic cement) forexternal plastering use. 1796, Parker James from England was granteda patent for what he called Roman cement a form of natural hydrauliccement by cleaning lumps of impure limestone (Concrete Networks,2014).
Itwas not until 1793 that the technique of making cement took a hugeleap forward when Smeaton John discovered modern technology formaking hydraulic lime for cement. This is where he heated limestonecontaining clay until it formed clinker, which was crashed intopowder. This cement was employed in the erection of EddystoneLighthouse in England (Concrete Networks, 2014). In 1824, AspdinJoseph made another important milestone with the invention of modernPortland cement. Aspdin called his cement Portland after a rockquarry that produced extremely hard stone. The first compressive andtensile testing of cement was done in Germany. Tensile strengthrefers to the ability of concrete to withstand tension forces. On theother hand, compressive strength refers to the ability of concrete toresist compression forces. These strengths were expressed in psi(pounds per square inch) (Concrete Networks, 2014).
Itis important to state that, prior to the discovery of Portlandcement, and even for many years afterwards, natural cement waslargely used in construction. This was made of a mixture of clay andlime. Due to the fact that nature assorts the elements of naturalcement, its properties varied significantly. Portland cement was madefrom a mixture of clay and limestone heated in a kiln (ConcreteNetworks, 2014). The clinker that emanates from this process is thencrushed and mixed with gypsum to reduce the rate of hydration andmake the cement workable for a long period. Edison Thomas wasreceived a patent for the first long kiln in 1890. With the kiln, itwas possible to provide better temperature control and mixing.
Inthe early years of the 19th-century, un-reinforced concrete was beingused extensively to construct houses. It was not until 1954 that thefirst patent for using iron bars as reinforcement was taken. In lateryears, engineers would start using steel. In the 20th century, arange of reinforcement materials were established, with uniquereinforcement arrangements and types. This era also saw theintroduction of color concrete by Lynn. The development of theprestressing techniques in the 1930s ushered a new era of elegant andslender structures made of concrete (Concrete Networks, 2014). Airentraining agents were also used in 1930s to increase capability ofconcrete to withstand thawing, damage and freezing. In 1970s fibrereinforcement commenced as a way to boost strength of concrete.Concrete continues to be used in diverse ways and a wide range ofapplications including industrial structures, multi-storey buildingand paving.
ConcreteNetworks. 2014. Timeline of Concrete & Cement History.Retrieved 16 March, 2015 from: Timeline of Concrete & CementHistory