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INTRODUCTION
Definition: “Cement is a crystalline compound of calcium silicates and other calcium compounds having hydraulic properties” (Macfadyen, 2006).
History
Lime and clay have been used as cementing material on constructions through many centuries.
Romans are commonly given the credit for the development of hydraulic cement, the most significant incorporation of the Roman’s was the use of pozzolan-lime cement by mixing volcanic ash from the Mt. Vesuvius with lime.
Best know surviving example is the Pantheon in Rome
In 1824 Joseph Aspdin from England invented the Portland cement
Types of Cement
Cements are considered hydraulic because of their ability to set and harden under or with excess water through the hydration of the cement’s chemical compounds or minerals
There are two types:
Those that activate with the addition of water
And pozzolanic that develop hydraulic properties when the interact with hydrated lime Ca(OH)2
Pozzolanic: any siliceous material that develops hydraulic cementitious properties when interacted with hydrated lime.
HYDRAULIC CEMENTS:
Hydraulic lime: Only used in specialized mortars. Made from calcination of clay-rich limestones.
Natural cements: Misleadingly called Roman. It is made from argillaceous limestones or interbedded limestone and clay or shale, with few raw materials. Because they were found to be inferior to portland, most plants switched.