COMPARATIVE ANALYSIS OF PORTLAND CEMENT IN SOUTHWESTERN NIGERIAN
CHAPTER ONE Introduction
Ordinary Portland Cement (O. P. C): a substance which binds together the particles of aggregates (usually sand and gravel) to form a mass of high compressive strength concrete. It is a combination of limestone or chalk with clay mixed in a proportion depending on the type of cement desired. Portland cement is the most common type of cement generally used around the world because it is a basic ingredient of concrete, mortar, stucco e.t.c. if a fine powder is produced by grinding Portland cement clinker more than 90 %, a limited amount of calcium sulphate shall consist of at least two-thirds by mass of calcium silicates (3CaO.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 oxide content (MgO) shall not exceed 5.0% by mass. Portland cement is the cement that only hardens by reacting with water but also forms a water-resistant product. Produce by pulverizing clinker consisting of one or more of the form of calcium silicates, usually containing one or more of the calcium sulphate (diameter 0.2 – 1.0 inch (5 – 25mm), the low cost and widespread availability of the limestone, shales, and other naturally occurring materials make Portland cement one of the lowest – cost materials widely used over the last century throughout the world. (Wikipedia, the free encyclopedia, 2011).
2.1 Background of the Study
Portland cement was developed from natural cements made in Britain in the early part of the nineteenth century, and its name is derived from it similarly to Portland stone, a type of building stone that was queried on the ISLE of Portland in Dorest, England.
Portland Cement originated from a British bricklayer from Leeds called Joseph Aspdin. It was one of his employees (Isaac Johnson) however, who developed the production technique, which resulted in more fast-hardening cement with a higher compressive strength in 1924.
The name “Portland cement” is also recorded in a directory published in 1823 being associated with a William Lockwood, Dave Stewart etc. Isaac Johnson’s cement was an artificial cement similar in properties to the materials known as “Roman Cement” (Patented in 1976 by James Parker) and his process was similar to the patented in 1822 and used 1811 by James Frost who called his cement “British Cement”.
Joseph Aspdin of Leeds England in 19th century was burning powered limestone and clay in his kitchen stove. By this crude method, he laid the foundation from an industry which annually processes literally maintains of limestone clay, cement rock and other materials into a powered so fine it will pass via a sieve capable of holding water. Cement is so fine that one pound of cement contains 150 billion grains.
Many people have claimed to have claimed to have made the first Portland cement in the modern sense, but it is generally accepted that it was first Portland Cement in the modern sense, but is generally accepted that it was first manufactured by William Aspdin at North fleet, England in about 1842. Aspdin’s Son William in 18443 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 he moved to Germany where he was involved in cement making and the German Government issued a standard on Portland cement in 1878. Each step in manufacture of Portland cement is cheeked by frequent and physical in plant laboratory. The finished product is also analyzed and tested and ensures that it complies with all specification. (Mehta,p.k 2008 concrete structure, properties, and material. Englewood cliffs, N. J. practice-Hall, Inc)..