Portland Cements, Calcium and Magnesium Compounds

Portland Cements, Calcium

and Magnesium Compounds

shelter, rest,

Overview Portland Cements Cement Manufacture Other Cements Calcium Compounds Magnesium Compounds Philippine Manufacturers Environmental Impacts Supply and Demand

History

Joseph Aspdin, a British stone mason October 21, 1824 Discovered an artificial cement Heating a mixture of finely ground

limestone and clay in his kitchen stove Calcination

PORTLAND CEMENTS

History

Aspdin named the product Portland Cement

It resembled a famous stone quarried on the Isle of Portland off the British Coast

He laid the foundation for today's portland cement industry

PORTLAND CEMENTS

What is the difference between cement and concrete?

Actually an ingredient of concrete. Closely controlled chemical combination of

calcium, silicon, aluminum and iron Lime and silica make up about 85% of the

finished product mass.

PORTLAND CEMENTS

Cement

Concrete

PORTLAND CEMENTS

Basically a mixture of aggregates and paste

Aggregates are sand and gravel or crushed stone; the paste is water and portland cement

Gets stronger as it gets older

Hydration Cement comprises from 10 to 15 percent of

the concrete mix, by volume. Through this process, the cement and water

harden and bind the aggregates into a rocklike mass.

This hardening process continues for years.

PORTLAND CEMENTS

Portland CementThe product obtained by pulverizing clinker consisting essentially of hydraulic calcium silicates, usually containing one or more forms of calcium sulfate as an interground addition.

PORTLAND CEMENTS

Clinker produced by sintering limestone and

clay during the cement kiln stage usually 3–20 mm in diameter

PORTLAND CEMENTS

Clinker CompoundsFormula Name Abbreviati

on

2CaO· SiO2 Dicalcium silicate C2S

3CaO· SiO2 Tricalcium silicate C3S

3CaO· Al2O3 Tricalcium aluminate C3A

4CaO· Al2O3· Fe2O3 Tetracalcium aluminoferrite C4AF

MgO Magnesium oxide in free state

M

PORTLAND CEMENTS

Reactions during Clinker Formation

Temperature (° C)

Reaction Heat Change

100 Evaporation of free water Endothermic

500 and above Evolution of combined water from clay Endothermic

900 and above Crystallization of amorphous dehydration products of clay

Exothermic

900 and above Evolution of carbon dioxide from calcium carbonate

Endothermic

900 – 1200 Main reaction between lime and clay Exothermic

1250 – 1280 Commencement of liquid formation Endothermic

1280 and above Further formation and completion of cement compounds

Endothermic on balance

PORTLAND CEMENTS

Types of Portland Cements Type I (Regular portland cements)- General purpose cement suitable for all uses. It is used in general construction projects such as buildings, bridges, floors, pavements, and other precast concrete products.

PORTLAND CEMENTS

Types of Portland Cements Type II (Moderate-heat-of-hardening and

sulfate-resisting portland cements)- Generates less heat at a slower rate and has a moderate resistance to sulfate attack. - Heat evolved should not exceed 295 and 335 J/g after 7 and 28 days respectively.

PORTLAND CEMENTS

Types of Portland Cements Type III (High-early strength [HES] cements)- Made from raw materials with a lime-to-silica ratio higher than that of Type I cement and are ground finer than Type I cements.- It contains higher proportion of tricalcium silicate.

PORTLAND CEMENTS

Types of Portland Cements Type IA Similar to Type I with the addition of air-entraining properties. Type IIA It is identical to Type II and produces air-entrained concrete. Type IIIA It is an air-entraining, high-early-strength cement.

PORTLAND CEMENTS

Air entrainment- intentional creation of tiny air

bubbles in concrete- bubbles are introduced into the concrete by the

addition to the mix of an air entraining agent, surfactant (surface-active substance, type of chemical that includes detergents).

- primary purpose is to increase the durability of the hardened concrete, especially in climates subject to freeze-thaw.

PORTLAND CEMENTS

Types of Portland Cements Type IV (Low-heat portland cements)- It has a lower percentage of C3S, C3A, low heat of hydration and develops strength at a slower rate than other cement types- Ideal for use in dams and other concrete structures where there is little chance for heat to escape.

PORTLAND CEMENTS

Types of Portland Cements Type V (Sulfate-resisting portland cements)- 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

Manufacturing ProceduresTwo types of materials needed for production: Calcareous (Rich in calcium)- Limestone [includes aragonite, marble,

chalk]- Cement rock [includes marl] Argillaceous (Rich in silica)- Clay- Shale

PORTLAND CEMENTS

Closed-circuit grinding – in preparing the raw materials, the fines are passed on and the course material returnedOpen-circuit grinding – the raw materials are ground continuously until its mean fineness has reached the desired value

PORTLAND CEMENTS

Grinding Hookupsa. single two-compartment mill in open circuit

b. two-compartment mill closed-circuited with air separator

PORTLAND CEMENTS

Grinding Hookupsc. two-stage setup with primary compartment closed-circuited

d. efficient two-or three-compartment circuit closed with screen and air separator

PORTLAND CEMENTS

Grinding Hookupse. highly efficient three-stage system closed-circuited in each stage

f. single-stage mill closed circuited with rake classifier

PORTLAND CEMENTS

Grinding Hookupsg. modern double-stage circuit employing four different types of separating equipment

PORTLAND CEMENTS

Wet process (original one) is being replaced by the dry process (new plants) because of the saving in heat, accurate control and the mixing of the raw mixture it affords. Wet process has slurry formation due to water added to it. The dry process does not require the addition of water.

PORTLAND CEMENTS

PORTLAND CEMENTS

Isomeric flowchart for manufacture of portland cement by dry and wet processes

Analyses of Portland Cements (in %)

CaO SiO2 Al2O3 Fe2O3 MgO Alkali Oxide

s

SO3

Regular Cement (Average of 102)

MinMaxAve

61.1766.9263.85

18.5823.2621.08

3.867.445.79

1.536.182.86

0.605.242.47

0.662.901.40

0.822.261.73

High-Early Strength (Average of 8): High C3S

MinMaxAve

62.1767.5064.60

18.022.919.9

4.107.506.00

1.704.202.60

------------

------------

2.202.702.30

Low-Heat-of-Hardening (Average of 5): Lower C3S and C3A, Higher C2S and C4AF

MinMaxAve

59.3061.5060.20

21.9026.4023.80

3.305.404.90

1.905.704.90

------------

------------

1.601.901.70

PORTLAND CEMENTS

Functions of CompoundsC3A Causes set but need

retardation (by gypsum)

C3S Responsible for early strength (at 7 or 8 days)

C2S and C3S Responsible for final strength (at 1 year)

Fe2O3, Al2O3, Mg and alkalies

Lower clinkering temperature

PORTLAND CEMENTS

CEMENT MANUFACTURE

Quarry face

loader

1. BLASTING

dumper

2.TRANSPORT

Quarry

crushing

conveyor

storage at the plant

3. CRUSHING & TRANSPORTATION

3. CRUSHING AND TRANSPORTATION : The raw materials, after crushing, are transported to the plant by conveyor. The plant stores the materials before they are homogenized.

1. BLASTING : The raw materials that are used to manufacture cement (mainly limestone and clay) are blasted from the quarry.

2. TRANSPORT : The raw materials are loaded into a dumper.

CEMENT MANUFACTURE

storage at the plant

Raw grinding and burning

conveyor

Raw mill

Raw mix

1. RAW GRINDING

preheating

kiln

cooling

clinker

2. BURNING

1. RAW GRINDING : The raw materials are very finely ground in order to produce the raw mix.

2. BURNING : The raw mix is preheated before it goes into the kiln, which is heated by a flame that can be as hot as 2000 °C. The raw mix burns at 1500 °C producing clinker which, when it leaves the kiln, is rapidly cooled with air fans. So, the raw mix is burnt to produce clinker : the basic material needed to make cement.

CEMENT MANUFACTURE

clinker storage

Gypsum and the secondary additives are added to the clinker.

Finish grinding

1. GRINDING

Grinding, storage, packing and

dispatch

silos

bags

dispatch

2. STORAGE, PACKING, DISPATCH 1.GRINDING : The clinker and the gypsum are very finely ground giving a “pure cement”. Other secondary additives and cementitious materials can also be added to make a blended cement.

2. STORAGE, PACKING, DISPATCH :The cement is stored in silos before being dispatched either in bulk or in bags to its final destination.

OTHER CEMENTSFor many corrosive conditions, portland cement is unsuitable. Hence many special cements have been developed, of which are industrially important

Pozzolans- A material which is not cementitious in itself

but which becomes so upon admixture with lime

- The early strength of such a cement is lower than portland cement, but within a year the strengths are equal

- It resists the corrosive action of saline solutions and seawater much better than portland cement

OTHER CEMENTS

High Alumina Cements- Calcium aluminate cement- Made by fusing a mixture of limestone and

bauxite (containing iron oxide, silica, magnesia and other impurities)

- Characterized by very rapid rate of development of strength and superior resistance to seawater and sulfate-bearing water

OTHER CEMENTS

Silicate Cements- Possess low coefficients of expansion- It withstand all concentrations of inorganic

acids except hydrofluoric. - Not suitable at pH values above 7 or in

presence of crystal-forming systems- Joining of bricks in chromic acid reaction

tanks and in alum tanks

OTHER CEMENTS

Sulfur Cements- Resistant to non-oxidizing acids and

salts- Should not be used in the presence of

alkalis, oils, grease or solvents- Generally accepted as a standard material

for joining bricks, tile and cast iron pipe

OTHER CEMENTS

Polymer Concrete- Polymer bonded concretes - Consist of aggregate plus resins such as

epoxy, methyl methacrylate or polyester- Rapid curing, corrosion resistance or

high corrosive strength- More expensive than regular portland

cement concrete

OTHER CEMENTS

Magnesium Oxychloride Cement- Sorel’s cement3MgO + MgCl2 + 11H2O 3MgO· MgCl2 ·11H2O- Crystalline oxychloride contributes the

cementing action to the commercial cements- Flooring cement with an inert filler and

coloring pigment- Strongly corrosive to iron pipes in contact

with it

OTHER CEMENTS

Limestone Sedimentary rock which is relatively

inert, except in the presence of a strong acid.

With the proper purity the rock deposit can be used to produce lime, a manmade chemical.

CALCIUM COMPOUNDS

Lime a general term for calcium-containing

inorganic materials (carbonates, oxide and hydroxide predominate)

CALCIUM COMPOUNDS

Uses Medical purposes Insecticides Animal food Gas absorption, precipitation, dehydration Paper-making, soap, rubber, varnish Manufacture of high grade steel and

cement

CALCIUM COMPOUNDS

Quicklime (Burnt lime) Calcium oxide (CaO) It is a white, caustic, alkaline crystalline solid

at room temperature. Dangerous form of lime

CALCIUM COMPOUNDS

Slaked lime (Hydrated lime) Calcium hydroxide, Ca(OH)2 It is a colorless crystal or white powder and

is obtained when calcium oxide (quicklime) is mixed, or slaked with water.

Used in many applications, including food preparation.

CALCIUM COMPOUNDS

Hydraulic lime Slaked lime, used to make lime mortar

(paste used to bind construction blocks together and fill the gaps between them)

Obtained from burning of limestone containing clay and other impurities

Hydraulicity is the ability of lime to set under water or wet conditions

CALCIUM COMPOUNDS

Lime CycleCALCIUM COMPOUNDS

Manufacture Lime has always been a cheap commodity because

limestone deposits are prevalent anywhere. The lumps sometimes found in overburned or

dead-burned lime result from changes in the calcium oxide itself, as well as from certain impurities acted upon by excess heat, recognized as masses of relatively inert, semi-vitrified material.

On the other hand, it is underburned lime if it often happens that rather pure limestone is calcined insufficiently and lumps of calcium carbonate are left in the lime.

CALCIUM COMPOUNDS

Manufacture The reactions involved are:

CalcinationCaCO3 ↔ CaO + CO2

ΔH1200-1300ºC = 4GJ/t of lime produced

HydrationCaO + H2O Ca(OH)2

ΔH = -66.5 kJ

CALCIUM COMPOUNDS

Manufacture The total heat required for calcining per ton of

lime produced may be divided into two parts, sensible heat to raise the rock to decomposition temperature and latent heat of dissociation.

CALCIUM COMPOUNDS

Rotary kilns Capacity of up to 1600t/day. Almost all lime

produced in the country is calcined through this one. The exterior of a rotary kiln is heavy steel and the interior is lined with refractory brick.

Have the highest capacity and produce lime of the most uniform quality but require the greatest capital investment, have a high energy consumption and need very expensive dust-collecting systems.

CALCIUM COMPOUNDS

Vertical kilns Have a hundreds of design Four imaginary zonal sections in common:

- storage- preheating- calcining- cooling

Limestone is charged into the top of the kiln and the cooled lime is discharged at the bottom

CALCIUM COMPOUNDS

CALCIUM COMPOUNDS

Dorrco FluoSolids system for producing lime from pulverized limestone or calcium carbonate sludge. This is a five compartment reactor.

Gypsum very soft sulfate mineral composed

of calcium sulfate, CaSO4·2H2O component of Portland cement used to

prevent the flash settling of concrete added about 4- 5% during the final grinding

CALCIUM COMPOUNDS

GypsumCaSO4·2H2O CaSO2· ½H2O + 1½H2O

ΔH25ºC = +69 kJ If the heating is at a higher temperature,

gypsum loses all its water and becomes anhydrous calcium sulfate, anhydrite

Calcined gypsum (the half water salt) can be made into wall plaster by addition of a filler material (eg. asbestos, wood pulp or sand)

Plaster of paris (without addition) can be used for making sculptures and craft projects

CALCIUM COMPOUNDS

Calcination of Gypsum Grinding the mineral and placing it in large

calciners holding 9 to 22 tons Temperature is raised to 120 to 150ºC, with

constant agitation to maintain uniform temp

The material in the kettle, plaster of paris or first-settle plaster, may be withdrawn and sold at this point, or it can heated further to 190ºC to make a second-settle plaster

CALCIUM COMPOUNDS

Calcination of Gypsum First-settle plaster is approximately the half

hydrate, CaSO4· ½H2O Second-settle plaster is anhydrous Practically all gypsum plaster sold in the

form of first-settle plaster mixed with sand or pulp

Second form is used in manufacture of plasterboard and other gypsum products

Gypsum may be calcined in rotary kilns similar to those used for limestone

CALCIUM COMPOUNDS

Hardening of Plaster Hydration chemical conversion

CaSO4· ½H2O + 1½H2O CaSO4· 2H2O

ΔH = - 2.9 kJ Plaster sets and hardens because the liquid

water reacts to form a solid crystalline hydrate

Hydration with liquid water takes place at temp below about 99ºC and thus gypsum must be heated above 99ºC for practical dehydration

CALCIUM COMPOUNDS

Miscellaneous Calcium Compounds Calcium carbonate [CaCO3]Whiting – pure, finely divided CaCO3

prepared by wet grinding and levigating natural chalkPutty – produced when whiting is mixed with 18% boiled linseed oil

CALCIUM COMPOUNDS

Miscellaneous Calcium Compounds Calcium sulfide [CaS]- Made by reducing calcium sulfate with coke- Main use is as depilatory in the tanning industry and in cosmetics- Employed in luminous paints (finely dived form)

CALCIUM COMPOUNDS

Miscellaneous Calcium Compounds Halide salts [CaCl2, Ca(OCl)2]- Main applications are to lay dust on highways, to melt ice and snow on highways in winter, to thaw cool in oil and gas as well fluids and as an antifreeze in concrete

CALCIUM COMPOUNDS

Miscellaneous Calcium Compounds Calcium arsenate [Ca3(AsO4)2]- Produced by the reaction of CaCl2, Ca(OH)2, NaH2AsO4· H2O (lime) , H3AsO4

- Used extensively as an insecticide and as a fungicide

CALCIUM COMPOUNDS

Miscellaneous Calcium Compounds Calcium organic compoundsCalcium acetate – employed largely in dying of textilesCalcium lactate – used in medicines and in foods as source of calciumCalcium soaps (stearate, palmitate and abietate) are made by the action of the sodium salts of acids on a calcium salt such as chloride. These are insoluble in water but soluble In hydrocarbons. Mainly used as waterproofing agents

CALCIUM COMPOUNDS

Magnesium One of the most widely distributed

elements, occupying 1.9% of the earth’s crust.

Occurs usually in the chloride, silicate, hydrated oxide, sulfate or carbonate, in either a complex or in simple salts.

MAGNESIUM COMPOUNDS

Uses Extensively in refractories and insulating

compounds Manufacture of rubber, printing inks,

pharmaceutical and toilet goods Air pollution control systems (removal of

sulfur dioxide from stack gases)

MAGNESIUM COMPOUNDS

ManufactureProduction of magnesium compounds by separation from aqueous solutions may be divided into four processes:1. Manufacture from seawater without evaporation, using seawater and lime as the main raw materials2. Manufacture from bitterns and mother liquors from the solar evaporation of seawater for salt3. Manufacture from dolomite and seawater4. Manufacture from deep-well brines

MAGNESIUM COMPOUNDS

The production of magnesium compounds from seawater is made possible by the almost complete insolubility of magnesium compounds by such a process depends upon the following:1. Means to soften the seawater cheaply, generally with lime or calcined dolomite2. Preparation of a purified lime or calcined dolomite slurry of proper characteristics3. Economical removal of the precipitated hydroxide from the large volume of water4. Inexpensive purification of the hydrous precipitates5. Development of means to filter the slimes

MAGNESIUM COMPOUNDS

MgCl2 + Ca(OH)2 Mg(OH)2 + CaCl2 ΔH = +9.46 kJ

MgSO4 + Ca(OH)2 + 2H2O Mg(OH)2 + CaSO4· 2H2O ΔH = - 13.3

kJ

MAGNESIUM COMPOUNDS

Purified magnesium compounds from seawater

MAGNESIUM COMPOUNDS

Flowchart for Mg(OH)2 from seawater and dolomite

Calcination2CaMg(CO3)2 2CaO + 2MgO + 4CO2

ΔH = +610.9 kJSlaking2CaO + 2MgO + 4H2O 2Ca(OH)2 + 2Mg(OH)2

ΔH = -168 kJPrecipitation2Ca(OH)2 + 2Mg(OH)2 + MgCl2 + MgSO4 + 2HO

4Mg(OH)2 = CaCl2 + CaSO4· 2H2O ΔH = - 22. 6

kJCalcination4Mg(OH)2 4MgO + 4H2O ΔH = +248.3 kJHydrochlorinationMg(OH)2 + 2HCl MgCl2 + 2H2O ΔH = + 44.7 kJ

MAGNESIUM COMPOUNDS

Magnesium Carbonates These vary from dense MgCO3 used in

magnesite bricks to the very low density 4MgCO3 · Mg(OH)2· 5H2O and 3MgCO3 · Mg(OH)2· 3H2O once employed for insulation

Most of these of employed as fillers in inks, paints and varnishes

MAGNESIUM COMPOUNDS

Oxides and Hydroxides of Magnesium

On heating magnesium carbonate or hydroxide, magnesium oxide (MgO) is formed. It is used in vulcanization of rubber, insulating material, refractory material, for making other magnesium compounds and as an abrasive

Magnesium peroxide is available from the reaction of magnesium sulfate and barium peroxide. It is employed as an antiseptic and a bleaching agent.

MAGNESIUM COMPOUNDS

Magnesium SulfatePrepared by the action of sulfuric acid on magnesium carbonate or hydroxite. It is sold on many forms, eg. Hydrate MgSO4 · 7H2O, Epsom salts. The less pure material is used extensively as sizing and as a fireproofing agent.

MAGNESIUM COMPOUNDS

Magnesium Chloride The compound resembles calcium chloride

and has many of the same uses. Application on ceramics, in the sizing of paper

and manufacture of oxychloride cement Main use is in the making of metallic

magnesium

MAGNESIUM COMPOUNDS

Magnesium Silicates Asbestos – mixed with varying qualities of

silicates of calcium and iron. Used in the making of many fireproof and insulating materials but its fibers have cancer causing characteristics.

Talc – pure magnesium silicate in the form of 3MgO· 4SiO2·H2O, found naturally in scapstone Its is employed as filler in paper, plastics, cosmetics and toilet preparations.

MAGNESIUM COMPOUNDS

CEMAP Cement Manufacturers’ Association of the Philippines

Formerly known as Cement Institute of the Philippines until 1965.

The association enjoyed the support of the Philippine government which recognized its importance in ensuring economic growth.

The early industry association’s goals were to pool the resources of the cement industry and to undertake various endeavors that would enhance its orderly growth and share in the development of the nation’s economy.

MANUFACTURERS

Cemex Philippines Group of CompaniesAPO Cement CorporationCEMEX is the only eco-labeled cement company in the Philippines. The APO Cement Plant is in Naga City, Cebu

Solid Cement CorporationLocated at Barangay San Jose, Antipolo City

MANUFACTURERS

Holcim Philippines, Inc.Bulacan, La Union, Lugait and Davao PlantsCurrently the biggest cement company in the Philippines. It was created by the merger in 2000 of the three cement companies carrying the Union Cement brand; Bacnotan Cement Corporation (BCC), Davao Union Cement Corporation (DUCC) and Hi Cement Corporation (HCC).

MANUFACTURERS

Lafarge Associated Companies Lafarge Republic, Inc. (LRI) - Bulacan

Plant Lafarge Republic, Inc. (LRI) -

Norzagaray Plant Lafarge Republic, Inc. (LRI) - Batangas

Plant Lafarge Republic, Inc. (LRI) - Teresa

Plant Lafarge Iligan, Inc. Lafarge Mindanao, Inc.

MANUFACTURERS

Northern Cement CorporationNorthern Cement Corporation was incorporated on February 10, 1967 and started commercial operations in 1969. It is located in Pangasinan.

MANUFACTURERS

Pacific Cement Philippines, Inc.It was organized and incorporated in 1964 to manufacture ordinary Portland cement. The plant comprises a Wet Process Single Production Line with an original rated capacity of 600 TPD. It is located at Surigao City.

MANUFACTURERS

Taiheiyo CementPhilippines, Inc.Formerly Grand Cement Manufacturing Corp. It is located in the town of San Fernando, Cebu. The facility sits on a limestone deposit estimated to last at least 100 years.

MANUFACTURERS

Environmental Impacts

Environmental Impacts

POLLUTION PROBLEMS

These include emissions of airborne pollution in the form of dust, gases, noise and vibration when operating machinery and during blasting in quarries, and damage to countryside from quarrying.

Equipment to reduce dust emissions during quarrying and manufacture of cement is widely used, and equipment to trap and separate exhaust gases are coming into increased use.

Carbon DioxideEmissions

The cement industry is one of two primary industrial producers of carbon dioxide (CO2), creating up to 5% of worldwide man-made emissions of this gas, of which 50% is from the chemical process and 40% from burning fuel.

The amount of CO2 emitted by the cement industry is nearly 900 kg of CO2 for every 1000 kg of cement produced.

POLLUTION PROBLEMS

Heavy Metal Emissions in the Air

The high-temperature calcination process of limestone and clay minerals can release in the atmosphere gases and dust rich in volatile heavy metals; thallium, cadmium and mercury are the most toxic.

POLLUTION PROBLEMS

Heavy Metals Present in the Clinker

The presence of heavy metals in the clinker arises both from the natural raw materials and from the use of recycled by-products or alternative fuels.

Nickel, zinc and lead are commonly found in cement in non-negligible concentrations.

POLLUTION PROBLEMS

World sales for cement are forecast to expand more than five percent annually through 2017 to over 4.7 billion metric tons. Demand will rebound sharply in North America and Western Europe, while growth in China will decelerate yet still achieve impressive gains. Blended cement will account for over three-fourths of all new demand.

SUPPLY AND DEMAND

SUPPLY & DEMANDCEMENT PRODUCTION 2013

SUPPLY & DEMAND

The Southeast Asian cement market can be categorized under three distinct clusters, namely: the large producers (Indonesia, Thailand and Vietnam), the midsized producers (Malaysia and Philippines), and the rest (Singapore, Cambodia, Laos, Myanmar, Brunei and East Timor).

The Philippines: Cementing growth

The Department of Budget and Management released its economic growth forecasts. GDP is expected to expand by between 6.6% and 7.6% in 2013 and by 7.4% and 8.6% in 2014, with industry – including construction, leading the charge.

One of the biggest economic growth in 2012 was the Philippines’ cement sector. According to the CEMAP, demand for cement rose by 18% in 2012, the sharpest increase in 15 years.

In 2013, Mr. Ernesto Ordoñez, president of the CEMAP, said higher spending from the government on infrastructure developments and increased investments in building developments would boost turnover.

SUPPLY & DEMAND

Thank You For Listening!~Zanny Barluado, 2014

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Portland Cements, Calcium and Magnesium Compounds

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