CE-303CE-303Lecture # 2Lecture # 2

Manufacturing of Portland Manufacturing of Portland CementCement

Prepared by: Dr. Salah Al-Dulaijan

Objectives of the LectureObjectives of the Lecture

• To explain the raw materials used in To explain the raw materials used in manufacturing of Portland cement.manufacturing of Portland cement.

• To explain briefly the manufacturing To explain briefly the manufacturing process of cement.process of cement.

IntroductionIntroduction

• Portland cement was invented in 1824 Portland cement was invented in 1824 by Joseph Aspdin, an English mason.by Joseph Aspdin, an English mason.

• Joseph Aspdin named his patented Joseph Aspdin named his patented product as “Portland cement” because product as “Portland cement” because it produced a concrete that resembled it produced a concrete that resembled the color of the natural limestone the color of the natural limestone quarried at Portland in England.quarried at Portland in England.

IntroductionIntroduction

• Portland cements are hydraulic Portland cements are hydraulic cements primarily composed of cements primarily composed of hydraulic calcium silicates. hydraulic calcium silicates.

• Hydraulic cements set and harden by Hydraulic cements set and harden by reacting chemically with water.reacting chemically with water.

• Most of the hydration and strength Most of the hydration and strength development take place within the first development take place within the first month of mixing, but they continue, month of mixing, but they continue, though more slowly, for a long time.though more slowly, for a long time.

Raw Materials used in Raw Materials used in Manufacture of Portland Manufacture of Portland

CementCement• The raw materials are generally The raw materials are generally

a mixture of a mixture of calcareouscalcareous (calcium (calcium oxide, CaO) and oxide, CaO) and argillaceousargillaceous (silica and alumina, SiO(silica and alumina, SiO22 and and AlAl22OO33).).

The raw materials used in the The raw materials used in the manufacture of Portland cement manufacture of Portland cement

contain appropriate proportions of contain appropriate proportions of the following:the following:

• Calcium oxide (CaO)Calcium oxide (CaO)Sources: Limestone, Shale, Marl, Sources: Limestone, Shale, Marl, Calcite, Argonite, Clay, Chalk, etc. Calcite, Argonite, Clay, Chalk, etc.

• Silica (SiOSilica (SiO22))Sources: Clay, Marl, Shale, Sand, Fly Sources: Clay, Marl, Shale, Sand, Fly ash, Calcium silicate, etc. ash, Calcium silicate, etc.

• Alumina (AlAlumina (Al22OO33))Sources: Aluminum-ore refuse, Clay, Sources: Aluminum-ore refuse, Clay, Fly ash, Shale, etc.Fly ash, Shale, etc.

• Iron (FeIron (Fe22OO33))Sources: Iron ore, Clay, Mill scale, Sources: Iron ore, Clay, Mill scale, Shale, etc.Shale, etc.

• Magnesia (MgO)Magnesia (MgO)

Sources: Cement rock, Limestone, Sources: Cement rock, Limestone, Slag, etcSlag, etc

• Gypsum (CaSOGypsum (CaSO44.2H.2H22O)O)

Sources: Calcium sulfate, Sources: Calcium sulfate, Anhydrite,Anhydrite,Gypsum, etc.Gypsum, etc.

Sources of Raw MaterialsSources of Raw Materials

Steps used in Manufacture Steps used in Manufacture of Portland Cementof Portland Cement

• Raw materials stones in appropriate Raw materials stones in appropriate proportions are first crushed to 125 proportions are first crushed to 125 mm size, then to 20 mm, and stored.mm size, then to 20 mm, and stored.

• Crushed raw materials are ground to Crushed raw materials are ground to powder and either blended in dry powder and either blended in dry condition (dry process or mixed with condition (dry process or mixed with water to form slurry, and blended water to form slurry, and blended (wet process).(wet process).

• After blending the raw After blending the raw materials the same is sent to a materials the same is sent to a rotating kiln for burning at a rotating kiln for burning at a temperature in the range of temperature in the range of 1350ºC to 1450ºC.1350ºC to 1450ºC.

• Mixing the raw materials while Mixing the raw materials while burning in the kiln lead to the burning in the kiln lead to the chemical reactions between chemical reactions between oxides of the raw materials by oxides of the raw materials by fusion, forming cement clinker.fusion, forming cement clinker.

• The clinker is cooled and then The clinker is cooled and then pulverized. During this operation a pulverized. During this operation a small amount of gypsum is added small amount of gypsum is added to regulate the setting time of the to regulate the setting time of the cement and to improve the cement and to improve the shrinkage and strength properties. shrinkage and strength properties.

• Clinker with gypsum are mixed and Clinker with gypsum are mixed and

ground to a desirable fineness, that ground to a desirable fineness, that passes through a 45 micrometer passes through a 45 micrometer No. 325 mesh) sieve. This grounded No. 325 mesh) sieve. This grounded product is the Portland cement.product is the Portland cement.

Rotary Kiln (Furnace)Rotary Kiln (Furnace)

ClinkerClinker

• The final product of a Portland The final product of a Portland cement contains the following four cement contains the following four chemical compounds:chemical compounds:

– Tricalcium silicate Tricalcium silicate (C(C33S)S)

– Dicalcium silicate Dicalcium silicate (C(C22S)S)

– Tricalcium aluminate Tricalcium aluminate (C(C33A)A)

– Tetra calcium aluminoferrite Tetra calcium aluminoferrite (C(C44AF)AF)

• C = CaO, S = SiOC = CaO, S = SiO22, A = Al, A = Al22OO33, F = Fe, F = Fe22OO33