Portland Cement

Portland cement is the most common type of cement in general usage in many parts of the world, as it is a basic ingredient of Concrete(i), It is a fine powder produced by grinding Portland cement clinker(ii) (more than 90%), a maximum of about 5% gypsum which controls the set time, and up to 5% minor constituents;(as allowed by various standards). As defined by the European Standard EN197.1, "(ii)Portland cement clinker is a hydraulic material which shall consist of at least two-thirds by mass of calcium silicates (3CaO.SiO2 and 2CaO.SiO2), the remainder consisting of aluminum- and iron-containing clinker phases and other compounds. The ratio of CaO to SiO2 shall not be less than 2.0. The magnesium content (MgO) shall not exceed 5.0% by mass." (The last two requirements were already   set out in the German Standard, issued in 1909).

 

Portland cement was developed from cements (or correctly hydraulic limes) made in Britain in the early part of the nineteenth century, and its name is derived from its similarity to Portland stone, a type of building stone that was quarried on the Isle of Portland in Dorset, England. Joseph Aspdin, a British bricklayer, in 1824 was granted a patent for a process of making a cement which he called Portland cement His cement was an artificial hydraulic lime similar in properties to the material known as "Roman Cement" (patented in 1796 by James Parker) and his process was similar to that patented in 1822 and used since 1811 by James Frost who called his cement "British Cement". The name "Portland cement" is also recorded in a directory published in 1823 being associated with a William Lockwood and possibly others. Aspdin's son William in 1843 made an improved version of this cement and he initially called it "Patent Portland Cement" although he had no patent. In 1848 William Aspdin further improved his cement and in 1853 moved to Germany where he was involved in cement making.(1)

Many people have claimed to have made the first Portland cement in the modern sense, but it is generally accepted that it was first manufactured by William Aspdin at Northfleet, England in about 1842.(2)  The German Government issued a standard on Portland cement in 1878. Although Cement production started in 1842 but Clinker Minerals/Phases;(Alite, Belite, Celite & Felite), were named by the Swedish researcher Törnebohm in 1889, who repeated Le Châtelier's work who described the clinker composition early on 1883, later the 3-oxides system CaO-SiO2-Al2O3 was completed by Rankin and Wright at the Carnegie Institute in 1915, and in 1930 XRD technique was used by Brownmiller and Bogue to quantify the clinker phases.(3) 

Following are some of the more significant dates in the development of Portland cement manufacturing(4) 

  • 1824 Aspdin patented Portland cement
  • 1845 Isaac Johnson recognized the significance of high temperature to produce C3S. This was the first cement as we know it.
  • 1880 Gypsum first added for set control.
  • 1885 Ransome patented the rotary kiln.
  • 1891 The continuously fed ball mill was patented.
  • 1928 Introduction of the grate preheater kiln (Lepol) by Polysius provided the first major improvement in thermal efficiency from the previous long, wet kilns.
  • 1930 Roller mill first applied to cement manufacture; rapid development after 1960.
  • 1930 Introduction of the roll press; rapid development after 1980.
  • 1932 Patent of the cyclone preheater kiln with commercial development by KHD dating from 1951.
  • 1937 Introduction of the grate cooler by Fuller.
  • 1950 Introduction of mechanical separator
  • 1960 KHD introduced the kiln bypass to allow use of raw materials with high volatiles contents.
  • 1966 Introduction of precalciner which was initially air-through riser-firing.
  • 1970 Introduction of high-efficiency separators.
  • 1973 Introduction by IHI of the flash calciner with tertiary air duct.
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Portland Cement Clinker contains approximately the following chemical constituents: (5)

 

SiO2

16 – 26 %

CaO

58 – 67 %

Al2O3

4 – 6 %

MgO

1 – 5 %

Fe2O3

2 – 5 %

K2O + Na2O

0 – 1 %

Mn2O3

0 – 3 %

SO3

0.1 – 2.5 %

TiO2

0 – 0.5 %

P2O5

0 – 1.5 %

Loss of Ignition (LOI)

0.5 – 3.00 %

 

 

 

Portland cement clinker can contain the following mineral phases:(6)

 

 

Designation

Range of Validity

Formula

Abbreviation*

Alite;(Tri-calcium silicate)

 

3CaO.SiO2

C3S

Belite;(Di-calcium silicate)

 

2CaO.SiO2

C2S

Celite;(Tri-calcium aluminate)

Al2O3 Fe2O3

3CaO.Al2O3

C3A

Felite;(Tetra-calcium aluminoferrite)

4CaO.Al2O3.Fe2O3

C4AF

Calcium aluminoferrite

Al2O3 < Fe2O3

2CaO.(Al2O3.Fe2O3)

 

Free lime

 

CaO

 

Free magnesium oxide

 

MgO

 

Alkali containing aluminate

K2O + Na2O > SO3

(K,Na)2O.8CaO.3Al2O3

(K,N)C8A3

Alkali sulfate

K2O + Na2O >/< SO3

(K,Na)2SO4

 

Calcium sulfate

K2O + Na2O < SO3

CaSO4

 

 

* Cement chemist notation (CCN) was developed to simplify the formulas cement chemists use on a daily basis

 

 

 

 

(i)Concrete

Now a day’s concrete is the most widely used building material in the world; it is the second most consumed substance on the earth after water, on average each year three tons of concrete is consumed by every person in the planet!(7)

Concrete is a composite material composed mainly of water, aggregate and cement. Often, additives and reinforcement are included in the mixture to achieve desired physical properties of the finished material. When these ingredients are mixed together, they form a fluid mass that is easily molded in the shape. Over a time, the cement forms a hard matrix which binds the rest of ingredients together into durable stone-like material with many uses(8)

Alvord lake bridge - San Francisco” was the first bridge built using reinforced concrete in 1889 by Ernest Ransome, the bridge survived an earth quick in 1906.
The reinforced concrete was invented in 1849 by Joseph Monier.

Additionally Calcium was discovered by Sir Humphry Davy in 1808, Silicon was discovered by Jöns Jacob Berzelius in 1824 & Aluminum was discovered by Hans Christian Oersted in 1825.(9)

Recommend this page on:

 [(1) J.R.Smith''.Modern cement plant''s-2010]

[(2) D.Campbell''. Microscopical Examination & Interpretation of Portland Cement &Clinker''].

[(3) http://www.cementkilns.co.uk/]

[(4) Alsop; ICR; 7/2002]:

[(5)&(6) Cement Data Book Duda 2nd edition]

 [(7) http://blogs.ei.columbia.edu/2012/05/09/emissions-from-the-cement-industry/]

 [(8) Zongjin Li; Advanced concrete technology; 2011]

 [(9) http://education.jlab.org/qa/discover_ele.html]

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