COMPARATIVE ANALYSIS OF PORTLAND CEMENT IN SOUTHWESTERN NIGERIAN

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 depend 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 which shall consist 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 as the cement that only harden by reacting with water but also forms a water-resistant product. Produce by pulverizing clinker consisting 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 wide spread availability of the limestone, shales and other naturally occurring materials make Portland cement one of the lowest – cost materials widely use over the last century throughout the world. (Wikipedia, the free encyclopedia, 2011).