portland cements i. types of cements 1. pozzolana and pozzolanic cements ( 火山灰水泥） 2....

Portland Cements

I. Types of Cements

1. pozzolana and pozzolanic cements (火山灰水泥）2. blastfurnace slag cements （炉渣水泥）3. high-alumina cements (高矾土水泥）4. special cements such as white, colored, waterproofe

d, 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.

1 Wednesday, April 19, 2023

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.


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;


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;


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.


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


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.


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.


Portland Cements

6. Tests on specifications of cement1) 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. Homework1. The manufacturing process of Portland cement.2. Ex. IV on page 43 in the main text book.


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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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.

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11 1 November 2004

portland cements i. types of cements 1. pozzolana and pozzolanic cements ( 火山灰水泥） 2....

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