Tipos de cemento

1. Portland Cements
I. Types of Cements
1. pozzolana and pozzolanic cements
2. blastfurnace slag cements
3. high-alumina cements
4. special cements such as white, colored, waterproofed,
masonry, oil-well, and expansive cements
5. Portland cement: common calcium silicate cement
II. *Portland Cements
1. History: In 1824, Aspdin, a British stone mason,
invented a cement which he named portland cement
because it resembled a stone quarried on the Isle of
Portland off the British Coast.
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2. Portland Cements
II. Portland Cements
2. Raw and processed materials: calcareous
materials like limestone and marl and argillaceous
substances like clay and shale, with major mineral
ingredients of calcium, silicon, aluminum, and
iron.
3. Constituents: tricalcium silicate(3CaO•SiO2 or C3S),
dicalcium silicate (2CaO•SiO2 or C2S), tricalcium
aluminate (3CaO•Al2O3 or C3A), and tetracalcium
alumino ferrite(4CaO•Al2O3•Fe2O3or C4 AF)
4. *Manufacturing Process:
1) Producing a cement that meets specific chemical
and physical specifications requires careful
control of the manufacturing process.

3. Portland Cements
II. Portland Cements
4. Manufacturing Process:
2) Breakdown process
(1) obtaining raw materials which are reduced by
primary and secondary crushers to 5-inch size
(125-mm), then to 3/4-inch(19 mm);
(2) proportioning the materials at the cement plant to
create a cement with a specific chemical
composition with two different methods, dry and
wet;
(3) Completing the grinding and blending operations
for the materials in slurry form;
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4. Portland Cements
(4) after blending, feeding the mixture of raw
materials into the upper end of a tilted rotating,
cylindrical kiln;
(5) forcing burning fuel consisting of powdered coal
or natural gas into the lower end of the kiln;
(6) heating the raw materials to very high
temperature, and at 2700ºF (1480º C), a series of
chemical reactions causing the materials to fuse
and creating cement clinker—grayish-black
pellets, often the size of marbles;
(7) Discharging the clinker red-hot from the lower
end of the kiln and then transferring it to various
types of coolers to lower the clinker to handling
temperatures;
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5. Portland Cements
(8) Combining the clinker with gypsum and grinding
the mixture to pass through a No. 200 mesh sieve;
(9) Packing and storing the gray powder—portland
cement
5. Types of Portland Cements
According to AASHTO and ASTM specifications, eight
types of portland cements are listed as follows:
 Type I: a normal, general-purpose cement suitable for
all uses
- used where the special properties of other types are not
required;
- used where cement or concrete is not subject to specific
exposures, such as sulfate attack, or to an
objectionable temperature rise due to heat generated
by hydration.

6. Portland Cements
-uses including pavements and sidewalks,
reinforced concrete buildings, bridges, railway
structures, tanks, reservoirs, culverts, sewers,
water pipes and masonry units
 Type IA: similar to Type I with the addition of air-
entraining properties only
 Type II: generating less heat at a slower rate and
with a moderate resistance to sulfate attack
-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
- usu. generating less heat at a slower rate than
Type I
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7. Portland Cements
-used in structures of considerable mass, such as
large piers, heavy abutments, and heavy retaining
walls, especially when the concrete is placed in
warm weather.
 Type IIA: identical to Type II with the addition of
air-entraining properties
 Type III: a high-early-strength cement, chemically
and physically similar to Type I, except that its
particles have been ground finer.
-providing high strengths at an early period,
usually a week or less
-used when forms are to be removed as soon as
possible, or when the structure must be put into
service quickly, especially in cold weather.
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8. Portland Cements
 Type IIIA: an air-entraining, high-early-strength
cement
 Type IV: with a low heat of hydration and
developing strength at a slower rate than other
cement types, making it ideal for use in dams and
other massive concrete structures where there is
little chance for heat to escape
 Type V: sulfate-resisting, used only in concrete
structures that will be exposed to severe sulfate
action, principally where concrete is exposed to
soil and groundwater with a high sulfate content.
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9. Portland Cements
6. Tests on specifications of cement
1) Chemical test: a chemical analysis of the proper
quantity of strength-giving compounds;
2) Physical test: fineness, stability, time of set, air
content, and compressive strengths of mortars
made using Ottawa sand
III. Homework
1. The manufacturing process of Portland cement.
2. Ex. IV on page 43 in the main text book.
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10. Portland Cements
1. In the dry process, dry raw materials are
proportioned, ground to a powder, blended
together and fed to the kiln in a dry state.
2. In the wet process, a slurry is formed by adding
water to the properly proportioned raw materials.
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11. Portland Cements
Specifications for air-entraining cements Types IA,
IIA, and IIIA 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, well-distributed, and
completely separated air bubbles. These cements
produce concrete with improved resistance to
freeze-thaw action.