TYPES OF PORTLAND CEMENT

                                               Cement

       Crystals precipitated from solutions within a pore or
void space.
       Major process involved in lithification of carbonate
sediments.
       Can be syndepositional to late diagenetic .            
     

  TYPES OF PORTLAND CEMENT 

Portland cement (often referred to as OPC, from Ordinary Portland Cement) is the most common type of cement in general use around the world because it is a basic ingredient ofconcrete, mortar, stucco and most non-specialty grout. It usually originates from limestone. It is a fine powder produced by grinding Portland cement clinker (more than 90%), a limited amount of calcium sulfate (which controls the set time) and up to 5% minor constituents as allowed by various standards such as the European Standard EN197-1:

     Portland cement is a closely controlled chemical combination of calcium, silicon, 
aluminum, iron and small amounts of other compounds, to which gypsum is added 
in the final grinding process to regulate the setting time of the concrete. Some of 
the raw materials used to manufacture cement are limestone, shells, and chalk or 
marl, combined with shale, clay, slate or blast furnace slag, silica sand, and iron 
ore. Lime and silica make up approximately 85 percent of the mass (1). 
The term "Portland" in Portland cement originated in 1824 when an English mason 
obtained a patent for his product, which he named Portland Cement. This was 
because his cement blend produced concrete that resembled the color of the 
natural limestone quarried on the Isle of Portland in the English Channel. 
Different types of portland cement are manufactured to meet different physical and 
chemical requirements for specific purposes. The American Society for Testing and 
Materials (ASTM) Designation C 150 provides for eight types of portland cement: 

TYPE I

Type I is a general purpose portland cement suitable for all uses where the special 

properties of other types are not required. It is used where cement or concrete is 

not subject to specific exposures, such as sulfate attack from soil or water, or to an 

objectionable temperature rise due to heat generated by hydration. Its uses include 

pavements and sidewalks, reinforced concrete buildings, bridges, railway 

structures, tanks, reservoirs, culverts, sewers, water pipes and masonry units. 

TYPE II

Type II portland cement is used where precaution against moderate sulfate attack 

is important, as in drainage structures where sulfate concentrations in 

groundwaters are higher than normal but not unusually severe (Table 2). Type II 

cement will usually generate less heat at a slower rate than Type I. With this 

moderate heat of hydration (an optional requirement), Type II cement can be used 

in structures of considerable mass, such as large piers, heavy abutments, and 

heavy retaining walls. Its use will reduce temperature rise -- especially important 

when the concrete is placed in warm weather. 

TYPE III

Type III is a high-early strength portland cement that provides high strengths at an 
early period, usually a week or less. It is used when forms are to be removed as 
soon as possible, or when the structure must be put into service quickly. In cold 
weather, its use permits a reduction in the controlled curing period. Although richer 
mixtures of Type I cement can be used to gain high early strength, Type III, highearly-strength portland cement, may provide it more satisfactorily and more 
economically. 


TYPE IA, IIA, IIIA

Specifications for three types of air-entraining portland cement (Types IA, IIA, and 
IIIA) are given in ASTM C 150. They correspond in composition to ASTM Types I, II, 
and III, respectively, except that small quantities of air-entraining materials are 
interground with the clinker during  manufacture to produce minute, welldistributed, and completely separated air bubbles. These cements produce concrete 
with improved resistance to freeze-thaw action. 

TYPE IV

Type IV is a low heat of hydration cement for use where the rate and amount of 
heat generated must be minimized. It develops strength at a slower rate than Type 
I cement. Type IV portland cement is  intended for use in massive concrete 
structures, such as large gravity dams, where the temperature rise resulting from 
heat generated during curing is a critical factor. 


TYPE V

Type V is a sulfate-resisting cement used only in concrete exposed to severe sulfate 
action -- principally where soils or groundwaters have a high sulfate content. Table 
1 describes sulfate concentrations requiring the use of Type V portland cement. Low 
Tricalcium Aluminate (C3A) content, generally 5% or less, is required when high 
sulfate resistance is needed.  For concrete pipe and precast box manufacturing, Type I or II cements are 
            generally used.