01-08-2012, 12:14 PM
CEMENT
CEMENT.ppt (Size: 1.47 MB / Downloads: 115)
INTRODUCTION
Definition: “Cement is a crystalline compound of calcium silicates and other calcium compounds having hydraulic properties” (Macfadyen, 2006).
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.
SOURCES OF CaCO3
LIMESTONES
Originate from the biological deposition of shells and skeletons of plants and animals.
Massive beds accumulated over millions of years.
In the cement industry limestone includes calcium carbonate and magnesium carbonate.
Most industrial quality limestones is of biological origin.
The ideal cement rock 77 to 78% CaCO3, 14% SiO2, 2.5% Al2O3, and 1.75% FeO3. Limestone with lower content of CaCO3 and higher content of alkalis and magnesia requires blending with high grade limestone
MARKETING
Wide distribution of plants minimizes the cost to customers.
In any market even though cement must meet certain specifications there are other factors that dominate, such as:
Delivered cost
Quality
Product consistency
Technical assistance and
Sales relationship with the user companies
Factors that drive the consumption of cement in the marketplace
Economic growth
Private and governmental capital investment
Population growth