CONTENTSNo. Content Page

Introduction 2Chapter (1) 1.1

1.2

Cement manufacture and blended cement Ordinary Portland Cement composition, types and manufacturingBlended cement

34

6

Chapter (2) 2.1 2.2 2.3

Characterization of pozzolanaDefinitionTypes and their compositionDifference between pozzolanic cement and pozzolana cement

89919

Chapter (3) 3.1 3.2 3.3

Lime and pozzolana mixturesPozzolanic reactionsThermal treatment of pozzolanaReaction products

20212324

Chapter (4) 4.1 4.2 4.3

Properties of pozzolana mixturesMicrostructure and porosity of pozzolana cementProperties of pozzolana containing mortarsEffect of pozzolana on durability

27283437

Chapter (5) 5.1 5.2

Experimental ResultsDetermination of free lime proceduresResults and discussion

495051

List of tables 53List of figures 45References 55

1

Introduction

Pozzolana is one of the mineral admixtures blended with the Portland cement clinker in an attempt to improve mechanical and physical properties for produced concrete. Pozzolana also reduces cost of cement manufacture where it replaces a part of clinker which production cost is high.

Most importantly the role of pozzolana in improving durability of concrete has provoked an increase in use of pozzolanic materials in cement manufacture.This research will include a simple characterization of pozzolana and a study of its effect on properties of cement.

2

Cement Manufacture and Blended Cement

3

Ch. (1): Introduction1-1. Ordinary Portland CementPortland cement is a hydraulic binding material most used in building and structures.1-Composition:It is composed of clinker which is a ground burnt mixture of raw materials, limestone and clay, and other additives that are used to improve quality and properties of clinker such as gypsum which control setting time of cement, mineral admixtures are added up till 15% of the total amount.A] Chemical compositionLime stone is composed of two oxides, CaO and CO2 , while clay is composed of SiO2, Al2O3 and Fe2O3; CO2 is removed by burning and the remaining four oxides are the main constituents of clinker in the following percentages:CaO 62-68%SiO2 21-24%Al2O3 4-8%Fe2O3 2-5% There are also other minor oxides that can affect quality of the clinker such as; MgO when it exist in percentage above 5% it is burned at 1500°c and slakes very slowly causing cracks in hardened concrete. Alkali oxides like Na2O or K2O in percentage above 1% cause failure in concrete.These oxides are not free in clinker, they exist in form of combined materials, and the main four compounds are:3CaO.SiO2 (alite) 45-65%2CaO.SiO2 (belite) 15-35%3CaO.Al2O3 (celite) 4-14%4CaO.Al2O3.Fe2O3 (celite) 10-18%Free CaO are not supposed to exist in clinker because it has the same effect of MgO but in wider range.B] Mineral compositionKnowing the minerals in clinker allow us to pre determine its physical and mechanical properties. Minerals in clinker are subdivided intoHigh alite C3S >60%Low alite C3S >50-60%Belite C2S >35%Aluminate C3A >12%Aluminoferrate C4AF >18%Varieties of OPC have altered percentages of each mineral according to the cement type.

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2- Types of OPC:Different types of Portland cement are manufactured to meet different physical and chemical requirements for specific purposes, such as durability and high-early strength. Eight types of cement are covered in ASTM C 150.

More than 92% of Portland cement produced is Type I and II (or Type I/II); Type III accounts for about 3.5% of cement production. Type IV cements is only available on special request, and Type V may also be difficult to obtain (less than 0.5% of production).

Although IA, IIA, and IIIA (air-entraining cements) are available as options, concrete producers prefer to use an air-entraining admixture during concrete manufacture, where they can get better control in obtaining the desired air content. However, this kind of cements can be useful under conditions in which quality control is poor, particularly when no means of measuring the air content of fresh concrete is available. If a given type of cement is not available, comparable results can frequently be obtained by using modifications of available types. High-early strength concrete, for example, can be made by using a higher content of Type I when Type III cement is not available, or by using admixtures such as chemical accelerators or high-range water reducers (HRWR). The common types of OPC are listed in the table bellow. Table (1-1)

Cement type

Use

I1 General purpose cement, when there are no extenuating conditions

II2 Aids in providing moderate resistance to sulfate attack

III When high-early strength is required

IV3 When a low heat of hydration is desired (in massive structures)

V4 When high sulfate resistance is required

IA4 A type I cement containing an integral air-entraining agent

IIA4 A type II cement containing an integral air-entraining agent

IIIA4 A type III cement containing an integral air-entraining

3- Manufacturing: •Raw materials must contain 75-78% CaCO3 and 22-25% of clayed materials, since there are no natural rocks with that composition, a mixture of limestone and clay is used in addition to the correcting admixtures to

5

compensate for oxides not exist in raw materials. For example insufficient in SiO2 calls for introduction of high silica materials such as (opoka or diatomite) •Also there is wide use in cement industry for waste and by-products of other industries such as blast furnace, slag or nepheline slime. •The fuel used is pulverized coal, fuel oil and natural gas.Steps of manufacturing flow sheet: •Quarrying lime stone and clay •Preparing raw materials and blending them •Burning mixture •Grinding with gypsum to fine powder with additionTechniques of manufacturing: •Dry method: raw materials are mixed, ground and burned dry with out water •Wet method: raw materials are mixed with water then ground and burned. •Combined method: to acquire advantages of both methods, raw materials are mixed with water, ground then dewatered before drying as granules.

1-2. Blended Portland Cements

Blended cement is a mixture of Portland cement and blast furnace slag (BFS) or a mixture of Portland cement and a pozzolana. The use of blended cements in concrete reduces mixing water and bleeding, improves finish ability and workability, enhances sulfate resistance, inhibits the alkali-aggregate reaction, and lessens heat evolution during hydration, thus moderating the chances for thermal cracking on cooling. Blended cement types and blended ratios are presented in table bellow. Table (1-2)

Type Blended IngredientsIP 15-40% by weight of pozzolana (fly ash)

I(PM) 0-15% by weight of Pozzolana (fly ash) (modified)

P 15-40% by weight of pozzolana (fly ash)IS 25-70% by weight of blast furnace slag

I(SM) 0-25% by weight of blast furnace slag(modified)

S 70-100% by weight of blast furnace slag

The advantages to using mineral admixtures added at the batch plant:

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Mineral admixture replacement levels can be modified on a day-to-day and job-to-job basis to suit project specifications and needs.

Cost can be decreased substantially while performance is increased (taking into consideration the fact that the price of blended cement is at least 10% higher than that of Type I/II cement [U.S. Dept. Int. 1989]).

GGBFS can be ground to its optimum fineness. Concrete producers can provide specialty concretes in the concrete

product markets.

Precautions must be considered when mineral admixtures are added at the batch plant:

Separate silos are required to store the different hydraulic materials (cements, pozzolanas, and slags). This might slightly increase the initial capital cost of the plant.

There is a need to monitor variability in the properties of the cementitious materials, often enough to enable operators to adjust mixtures or obtain alternate materials if problems arise.

Possibilities of cross-contamination or batching errors are increased as the number of materials that must be stocked and controlled is increased.

7

Characterization of Pozzolana

Ch. (2): Characterization of Pozzolana2-1. Definition

8

The term Pozzolana has two meanings; the first is that pyroclastic rocks mainly glassy or zeolitised which occur near Pozzuoli (ancient Puteoli, Italy) or near Rome. The second meaning is those artificial or natural materials that harden when mixed with water in presence of lime or any material that release calcium hydroxide (Portland cement). The interest here will be of the latter definition since it is more general.For along time the interest in Pozzolana was restricted to Italy where natural Pozzolana was found. In other countries that interest is rather recent, arises from the need to reuse waste materials such as fly ash and silica fume. Many studies have confirmed that pozzolanic cement yield concrete showing a high ultimate strength and great resistance to aggressive attacks.Establishing a classification for pozzolanic materials has proven difficult since that name include materials of different composition and mineralogical and geological origin. The more common classification is of the origin of Pozzolana, a subdivision to natural and artificial pozzolanas. This division is not very well defined since there are materials that originally pozzolanic but contain other components which takes on clear pozzolanic action only by firing.

2-2 .Types & Their Composition

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

Mixed origin

Sedimentary origin

Volcanic originNatural

TuffsIncoherentOther materials

Micro silica

Burned clays and shale

Fly ashArtificial

Class (C)Class (F)Table (2-1)

Natural pozzolana(a) Volcanic origin:Pyroclastic rocks result from explosive volcanic eruptions. Rapid pressure decrease during eruption causes the gases dissolved in liquid magma to be released forming microscopic bubbles in particles, forming a micro porous structure. At the same time particles are subjected to quenching process responsible for the glassy state. The material can be deposited on ground or in water, ground deposits are loose and heterogeneous, they are composed of ashes mixed with ducts fragments.Non explosive eruptions produce weak quenching which is not sufficient to prevent crystallization which give no or little pozzolanic effect.

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1- Incoherent materials; glassy volcanic pozzolanas. Most common example is Italian pozzolana form Campania.The following table shows the chemical composition of some incoherent volcanic pozzolana by percentage.

LOISO3TiO2K2ONa2OMgOCaOFe2O3Al2O3SiO2Pozzolana

3.050.650.317.613.081.239.054.2917.8953.08Bacoli

4.42Tr.0.791.121.646.6612.259.8119.1844.07Barlie

3.82Tr.0.066.351.024.758.5210.2518.4446.84Salone

9.680.150.080.170.875.244.8611.5916.4450.48Vizzini

2.64.4714.554.3Volvic

3.51.135.519.5365.1Santorin earth

2.214.536.121.332.482.8515.8958.91Rhine tuffash

3.431.924.973.352.5414.5665.74RhyolitePumicite

1.850.252.3931.332.611.0214.5669.34Furue shirasu

6.50.142.551.530.541.11.1411.4671.77HigashiMatsuyama

Table (2-2) LOI: loss on ignition

The mineralogical composition of some in coherent volcanic pozzolanas is shown below in the table.

Inert PhaseActive PhaseCountryPozzolanaQuartz, feldspar, augite,GlassItalyBacoli

Pyroxene, olivine, mica, analcime

Partially decomposed glass

ItalyBarlie

Leucite, Pyroxene, alkali feldspare, mica

Glass, analcimeItalySalone

Feldspare, quartz, olivine, clay

GlassItalyVizzini

Andesine, quartz, diopsideGlassFranceVolvic

Quartz, anorthite, labradorite

GlassGreeceSantorin earth

Quartz(9%), feldspar(15%)

Glass (55-60%)GermanyRhine trass

Quartz(19%), feldspar(15%)

Glass (62-67%)Chabasite(3%)Analcime(5%)

GermanyBavaria trass

10

Clay(5%), calcite, quartz, feldspar

Glass (80%)USARhyolitePumicite

Quartz(1%), anoethite(3%)

Glass (95%)JapanFurue shirasu

Quartz(1%), anoethite(1%)

Glass (97%)JapanHigashiMatsuyama

Table (2-3)

(2) Compact materials (tuffs); the deposits of volcanic pozzolana could contain compact layers as a result of weathering, which can cause zeolitisation or agrillation. Zeolitisation increase pozzolanic activity and agrillation cause decrease in it. Chemical composition of some tuffs is shown in the following table.

LOISO3K2ONa2OMgOCaOFe2O3Al2O3SiO2Pozzolana

11.15.061.481.24.945.8118.2952.12Bacoli

7.412.061.910.943.394.4116.4762.45Barlie

16.330.261.012.836.4315.1855.69Salone

6.340.10.412.762.7112.2873.01Vizzini

9.116.383.430.953.663.8217.754.68Volvic

7.270.181.643.732.6611.3267.7Santorin

earth

12.061.4514.6141240.9Rhine tuffash

3.052.351.221.934.0110.0371.63RhyolitePumicite

9.040.343.441.80.520.880.8111.7771.65Furue shirasu

9.50.271.661.660.152.072.5711.7971.11Higashi

MatsuyamaTable (2-4)

In some deposits transformation of pozzolana and incoherent glassy layers into compact tuffs is evident. Pozzolana in common is separated from tuffs with an intermediate layer. The composition of those three layers is shown in the following table.

Yellow tuffsIntermediate layerPozzolana51.3654.356.04SiO2

0.420.420.42TiO2

0.030.050.03ZrO2

16.8417.417.79Al2O3

3.92.652.07Fe2O3

11

0.842.122.8FeO0.140.150.12MnO0.990.921.19MgO3.473.613.47CaO0.050.080.06BaO6.576.937.43K2O2.5734.17Na2O0.090.060.05Cl2

0.040.050.05SO3

0.130.080.1P2O5

0.44CO2

4.962.650.6H2O-

7.555.73.79H2O+

100.39100.17100.18TotalTable(2-5)

The relation between loose pozzolana layer and layer of tuffs is proved by reproducing the (pozzolana → yellow tuffs) transition. Bucoli pozzolana underwent hydrothermal treatment resulting in a material similar to yellow tuffs. Chemical composition does not change but the original component was transformed into zeolitic materials confirming the large capacity of pozzolana for zeolitisation. Rate of transformation and type of mineral resulting depend on autoclaving conditions and chemical activator used. The table shows the mineral composition of transformed materials.

Contents(%)

MineralHeulandite

form theigarhorn

Tokay mountain

tuffsGorenje tuffsZaloska tuffs

68±362±3Clinoptilolite10011±118±1Heulandite

45±2Analcime15±128±219±1α-Quartz5±1Cristobalite

TracesMontmorilloniteTracesIllite

24±1AndesineTracesChlorite

Table (2-6)

(b) Sedimentary origin:

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Clays and diatomaceous earths are sedimentary rocks capable of combining with lime. Clays originate from alternation of igneous rocks. Diatoms originate from siliceous skeletons of microorganisms deposited in water.Both clays and diatoms occur mixed together. Clay minerals alone can react with lime but can not be used as pozzolana due to increased water demand and lowering of strength. Diatomaceous earths, also called moler, consist of mixture of montmorillonite and amorphous opal, used either as it is or calcined to improve pozzolanic properties. Chemical composition of some diatoms is shown in table:

LOISO3K2ONa2OMgOCaOFe2O3Al2O3SiO2Pozzolana

2.151.381.420.431.341.16.728.6275.6Moler

8.290.210.210.61Tr.1.842.385.97Diatomite

11.932.291.925.86.360.04Diatomite

Table (2-7)( c )Mixed origin:

In north Rome there are some deposits composed of materials of different origin.Chemical composition of some of those materials is presented in the table below:

LOISO3K2ONa2OMgOCaOTiO2Fe2O3Al2O3SiO2Pozzolana

7.940.770.260.160.581.220.443.0285.5Sacrofano

6.10.20.72.790White earth-

a

8.42.41.554.584.25White earth-

b8.61.551.512.278.4Whit earth-c

7.52.351.721.456.8White earth-

d

0.110.110.230.191.10.412.4487.75Beppu white

clay5.90.861.042.43.27.179.55Gaize

Table (2-8)The presence of diatoms with fragments of volcanic rocks shows that these deposits originate from deposition of materials of different origin in stagnant water followed by acid attack.

Artificial pozzolana(a)Fly ash:

It consists of finely divided ashes produced by burning of pulverized coal in power plants.

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Owing to high temperature reached in burning, most minerals of coal are melted to small drops, sudden cooling transforms them into spherical glass particles. Chemical composition of bituminous fly ash(class F), low lime, is shown in table below:

LOICSO3K2ONa2OMgOCaOFe2O3Al2O3SiO2Country

4.74.490.541.881.726.2527.0151.68France

11.74.060.561.821.416.524.6848.1France

2.741.042.222.476.0224.4155.74Belgium

10.391.10.2413.934.1523.2148.75Taiwan

1.270.620.281.541.6211.728.150.09UK

2.90.82.90.82.83.68.623.950.8Poland

2.130.73Eq.2.711.973.9511.622.2753.98Denmark

3.954.432.042.244.326.5325.7450.46Netherlands

2.40.32.30.712.125.317.747Canada

1.60.41.351.51.35.1426.157.5Japan

2.30.371.70.31.53.34.538.248UK

3.442.141.752.21.65.856.2323.5553.53Japan

0.921.342.050.820.894.4815.7119.0152.24USA

51.1Eq.4.40.83.516.222.143.8Canada

3.30.53.10.61.23.46.829.651.2Germany

Table (2-9)Class F fly ash has few mineral phases, beside the prevailing vitreous ground mass, only four compounds are present: quartz, mullite, hematite and magnetite.The mineral composition of this class is presented in the following table:

AnhydriteGlassCarbonMagnetiteHematiteMulliteQuartzFlay ash source

773.11.42.7114.5Dunston

861.51.91.66.52.8Ferrybridge

830.61.22.1103.5Hams hall

712.42.52.4148.5Rye house

792.12.69104.1Skeleton Grange

45477287Northeast

P26

703792Northeast

P2795.40.72.11.8EFA

71.60.522.85.1LM

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11.475.82.710.417.1Lubbenan

12.974.33.81.91.4Eophenhain

16.974.315.72Swarze Pumpe

9.480.22.26.22Vackarode

3.385.16.15.10.3Hagenwerder

0.793.65.13.81.8Hershfeld

Table (2-10)The microprobe analysis of types of class F fly ash show chemical heterogeneity of particles. This is shown in the following table; [Table(2-11)]

CaOFe2O3Al2O3SiO2No.

2336.1581

6.333.153.12

5.142.951.13

18.49.624.243.54

712.930.242.55

4.617.929.342.16

26.824.242.17

20.829.5428

Ash particles classification is shown in the following table:commentsSizetexturecolourshapeType

0-20

10-50

a- glassy, clear, solid

b-glassy with bubbles

c-glassy with trace crystalline

d-most crystalline, solid

ColorlessSpherical & round

1

Deep color indicate iron

5-30Light color are glassy, all solid

Light brown to black

Spherical & round

2

Bubbles give foam or

cenospheres

10-200

Glassy, spongyWhiteRounded3

Irregularity very marked

10-100

Partially crystalline, solid

Light brownIrregular4

Agglomerated particles

contain red

50-500

Partially crystalline, solid

VaricoloredIrregular5

15

areasPartially burnt coal contain

some minerals

20-200

Solid or porousBlackIrregular6

May be quartz10-100

crystalline, solidColorlessAngular7

May be hematite

5-50crystalline, solidRedAngular8

Table (2-12)There is another type of fly ash, Class (C) which has high lime content, this is resultant from sub bituminous coal and lignite combustion. The chemical composition of this class is shown in the table below:

Free lime

LOISO3K2ONa2OMgOCaOFe2O3Al2O3SiO2Country

0.40.62.2104.625.252.3Saudi Arabia

3.94.60.50.1122.1616.444.4Poland

6.261.870.411.744.9922.965.8918.5638.67Canada

11.42.34.31.70.31.924.98.717.349.8Spain

104.555.570.80.171.8442.16.5910.626Greece

0.170.520.25 b1.057.98620.951.3USA

0.051.50.89b20.97.715.544.6USA

0.532.211.56 b4.8227.45.122.932.8USA

18.62.46.20.20.22.5475.512.827.4Turkey

5.51.410.60.70.98.119.97.79.140.6Turkey

9.80.44.80.40.11.925.44.422.339.9Turkey

1.060.182.870.93.823.16a7.7123.4155.42Italy

0.141.160.966.052.9213.34.9121.947.9Canada

Table (2-13)a: Low-lime lignite b: Na2O equivalent Unlike class F, class C has many mineralogical phases due to variable chemical composition. By XRD analysis we can identify: quartz, lime, periclase, anhydrite, ferrite, spinel, merwinite, alkali sulfate, melilite, sodalite and hematite.The mineralogical composition of this class is presented in the following table:

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HL3HL2HL1Mineral5.15.64.5Quartz9.85.518.6Lime7.49.312.2Anhydrite

~20~15~28Plagioclase264Hematite

0.62.50.8Magnetite4.31.21Mullite

~50~50~30Amorphous and

glassTable (2-14)

The difference between class F and class C fly ash concerns the chemical and mineral composition and the structure of the glass. These differences are highlighted by the change in X-ray diffraction background induced by the glass. The relation between content of CaO and the position of maximum of X-ray in background is shown in the figure:

Figure (2-1))b( Burned clay and shale:Clay gains a pozzolanic activity when burned at temperature between 600-900°c. Theses artificial pozzolanas are composed mostly of silica and alumina. The loss of combined water at burning cause the crystalline structure to be destroyed, silica and alumina become in a messy and unstable amorphous state. Heating does not affect on anhydrous minerals, so the pozzolanic activity depends on the clay minerals and the thermal treatment conditions. The chemical composition varies according to the origin. Silica content can vary between 22-42%, and lime can vary between 22-55%.Burned shales have more complicated mineral composition than burned clays depending on the chemical composition and temperature and duration of burning. For example a burned shale at 750-840°c contain minerals already

17

exist in shale like: β-quartz, α-cristobalite, calcite, α-ferric oxide and muscovite; and other minerals formed by burning like: gehlenite, anorthite, wollastonite, orthoclase, anhydrite, β-C2S, CA and CaO.

)c( Micro silica or silica fumes:The manufacturing process of silicon metal and ferrosilicon alloy in electrical arc at temperature up to 2000°c generate fumes containing spherical micro particles of amorphous silicon dioxide due to the reduction of quartz to silicon. The gaseous silicon dioxide is transported by combustion gases to lower temperature zones where it is condensed to tiny particles.The main properties of micro silica are the high silica content, high specific surface area and amorphous structure. The chemical composition of the micro silica is shown in the table below:

75% FeSiSi metal manufacture86-9097-98SiO2

0.8-2.30.2-1.3C0.3-10.02-0.15Fe2O3

0.2-0.60.1-0.4Al2O3

0.2-0.60.08-0.3CaO1-3.50.3-0.9MgO

0.8-1.80.1-0.4Na2O1.5-3.50.2-0.7K2O0.2-0.40.1-0.3S

2-40.8-1.5LOITable (2-15)

Micro silica particles are spherical and have average diameter of 0.1μm. The specific surface area ranges from 15 to 25 m2/g. It may contain traces of quartz, low-lime silica fume shows a high degree of condensation of silicate ions since it is formed by polymeric species.

2-3. Difference between pozzolanic cement and pozzolana cementWhen pozzolana is mixed with Portland cement and water, it reacts with calcium hydroxide formed during hydration of calcium silicates. As a result the final portlandite content in hydration products is always lower than it is in Portland cement alone. The simultaneous existence of cement and pozzolana modifies the hydration products. Pozzolanic cements are mixes of pozzolana and cement that if dispersed in excess water under certain conditions give rise

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to unsaturated calcium hydroxide solution. Pozzolana cement do not comply with this requirements, as their pozzolana content is insufficient to combine all portlandite formed during hydration of calcium silicates to give unsaturated lime solution. Hardened pozzolanic cement lack for free lime, while pozzolana cement does not. Portlandite content depends on the activity of pozzolana, amount of lime released and pozzolana/cement ratio. Pozzolana can be added at the plant or at the building site. In the first case, pozzolana undergoes either grinding with clinker and gypsum or separate grinding followed by mixing and homogenization. In the latter case, pozzolana is introduced into concrete mixer along with Portland cement. This procedure improves quality in term of strength and stability, but it causes certain decline in properties of concrete when pozzolana is added as partial replacement for Portland cement. Yet, this procedure is not recommended for the following reasons:•degree of homogenization reached is lower •replacing large part of Portland cement with pozzolana reduces early strength•building yards rarely have personnel, equipment and time required for checking properties of pozzolana and mixes.

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Lime and Pozzolana Mixtures

Ch (3): Lime and Pozzolana mixtures3-1. Pozzolanic reactionsPozzolanic activity covers all reactions occurring between active constituents of pozzolana, lime and water. There is great difficulty in evaluating pozzolana's active phases so, the progress of reaction is followed in term of diminution in free lime in system or the increase in silica+ alumina soluble in acid using the Florentin attack method. The activity of pozzolana includes two parameters, the maximum amount of lime that pozzolana can combine

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and the rate at which this combination occur. The heterogeneity of pozzolana and the complexity of hydration phenomena do not allow a model of pozzolanic activity only enables a general trend identified.

Figure (3-1)From the figure above, when water is in excess, amount of combined lime vary according to type of pozzolana. After 180 days pozzolanas have combined 45-75% of lime. In pastes, lime combination is lower than it is in hardened mass. The factors affecting amount of combined lime:1- Different pozzolanas have different capabilities to combine lime, as shown in the table below;

Calculated lime reaction

Average amount in trass

Free alkaliLime

reactionMineral

component K2ONa2O

5.5130.41.543Rhenish

trassQuartz

17.5150.21.1117Feldspar5.461.81.390Leucite13.37310.7190Analcime0.722.10.334Kaolin200552418364Glass phase

242.598---------------------Total

1796666272Glass phase

Bavarian--------------3.13.7176Obsidian

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glassTable (3-1)

2- The larger the amount of combined lime, the higher the content in the active phase and the lower the content in the inert phase.3- The amount of combined lime is related to the SiO2 content in the active phase which ranges between 45-75% in volcanic glass and fly ash but reach 95% in active amorphous micro silica.4- Within certain limits the amount of combined lime increase as lime/pozzolana ration increase, as shown in figure below;

Figure (3-2)5- Combined lime also depends on curing time, but the rate varies between types of pozzolana. The following figure illustrates effect of curing time on the combination amount.

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Figure (3-3)6- Short term activity depends on the specific surface area (BET) of pozzolana, while long term activity better referred to the chemical and mineralogical composition of pozzolana.7- The larger the amount of water the higher the rate of combination, thus the pozzolanic reaction is slower in paste.8- The rate of pozzolanic reaction increase by the increase in temperature, as seen from the following graph;

Figure (33-4)3-2. Thermal treatment of pozzolanasWhen heated, pozzolana undergoes chemical and structural transformation that may change, to a positive or negative extend. The resulting effect, an increased or decreased pozzolanic activity, depends on type of pozzolana, temperature and duration of heating. The negative effect induced by temperature explains the apparent contradiction that occurs in some materials.

23

If temperature is raised step by step, combined lime increase then decreases. The following figure shows this effect, it also shows that heating is followed by a decrease in specific area.

Figure (3-5)This means that optimum thermal treatment must be defined for each pozzolana by means of testing. For most pozzolanas the heating is done at 70-800°c, higher temperature improve deverification, crystallization and densification and formation of more stable phases. Micro structural changes by calcinations are evident in natural pozzolana due to the variation in refraction index.3-3. Reaction productsReaction of lime and pozzolana give similar products to those found in hydration of Portland cement since the overall chemical composition of both mixes falls in the same field. For the same reason different types of pozzolana give the same products. The table below shows the difference between hydration products in pastes and in hydration in excess water.

Rhine trass

Neapolitan yellow tuffs

Dehydrated Kaolin

SengiBacoli

bababababa++++++++++C-S-H++++++++++C2ASH8

++-+------C4AH13

--+---+++-C3A.CO3.H

12

-------+--C3AS3

C3AH6

a: reaction time in water=90 daysb: w/s ratio=0.4 ; pastes cured for 5 years

Table (3-2)Excess water accelerates final stage of reaction. The hydration products formed in pastes are smaller in size and more irregular.

24

By extending reaction time between lime and pozzolana in solution, there are some compounds are recognizable such as hex. Ca-aluminate, ca-silicate hydrate, carboaluminate, gehlenite hydrate and hydrogarnet. The following table shows nature and amount of hydrated compounds;

C2ASH8C3A.CaCO3.H12

C4AH13

C3AH6

C3AS2H2

C-S-H

Age

Curing temp.

Pozzolana

-+-+720,40,6

0Furue

(+)+++(+)+++

18020,40,6

0Shirasu

-(+)--720

-+-+++

18020

-(+)-(+)740Higashi

-(+)-+++

18040Matsuyam

a---+760Tuff(G)

---+++

18060

++++--720++++++(+)(+)18020(+)+-(+)740Kanto

(+)(+)+++(+)18040(Hachoiõji

)-(+)+++++(+)760Loam(R)--+++++18060

---+720,40,6

0Beppu white

---+++

18020,40,6

0Clay(V)

-+++(+)-720-++--18020-+(+)-740Tominaga

-+++-18040Masa

soil(M)-++-760-(+)+++(+)18060

---+720,40,6

0Takehara

(+)+-++18020,40,6

0Fly ash (T)

Table (3-3)When gypsum occurs in the paste, ettringite can be formed, formation of ettringite causes paste to crumple.

25

The C/S ratio in C-S-H is variable and depends on the type of pozzolana, time and temperature of curing, the lime/pozzolana ratio and analytical method used. The variability of C/S ratio is attributed to non-staichiometry of C-S-H, depending on chemical composition of the pore solution. The progress of pozzolanic reaction is marked by changes in distribution of silicate ions in the reaction products. SO4- in low lime fly ash dissolves in lime and water and cause ettringite and gypsum to precipitate. The rate of ettringite formation depends on rate of alumina dissolution. If ash is washed with water the sulfate occur in soluble form and both ettringite and gypsum are not formed. Low lime fly ash mixed with water and lime form C-S-H, C4AH13 and C2SAH8 and some times ettringite. High lime fly ash which contain high amount of free lime when mixed with water transform to Ca(OH)2so it doesn't need any lime addition, so they corresponds to artificial hydraulic limes. High lime fly ash may contain C2S, in this case hardening occur due to pozzolanic reaction and hydration of hydraulic components. In any case C-S-H, C4AH13, carboaluminate, gehlenite hydrate and ettringite are formed. If lime combine with Al2O3 and SiO2 there will be no pozzolanic action. The reaction of silica fumes and Ca(OH)2 is very rabid and causes a phase to precipitate on silicon peroxide, this layer is unstable and turns to C-S-H rabidly. In pastes, owing to high reactivity of silica fume, free lime disappear generally between7 and 28 days. In all hydrations the product C-S-H is more crystalline than that found in Portland cement.

26

Properties of Pozzolana and Cement Mixture

Ch (4): Properties of pozzolana mixtures4-1. Microstructure and porosity of pozzolana cementPorosity of pozzolana-containing pastes;

27

It is an intrinsic property of cement which can be limited but not eliminated. It influences the strength and permeability of paste, mortars and concretes.All aspects of strength are related to total porosity where permeability depends on structure and size distribution of the pores. Porosity depends on :

1- decrease by decrease in water ratio2- decrease by increasing curing period3- increase by increasing curing temperature4- differs according to type of cement

Correct determination of porosity and pore size distribution is a difficult target. Difficulties come from structure alternation that method of sample preparation and determination induces. Determination involves preliminary removal of water from pores of the paste and filling the same pores with a suitable fluid. Water removal obtained by:

1- Oven drying2- D-drying( under vacuum over a dry ice trap)3- P-drying( under vacuum over magnesium per chlorate hydrate)4- Sublimation5- Solvent replacement

Methods of porosity determination are:1- mercury intrusion under pressure2- helium displacement at low pressure3- methanol displacement at low pressure4- water intrusion5- nitrogen sorption

The relevant distribution curve allows calculation of:1- Threshold diameter (TD): pore diameter at which continuous mercury

intrusion begins2- Maximum continuous diameter (MCD): maximum pore diameter

corresponding to the main pore frequency3- Main peak intensity (PI): frequency of pore corresponding to MCD

Influence of drying procedure on porosity and pore size distribution is illustrated in the following figure:

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Figure(4-1)These results show:

1- Oven drying result in partial distribution of pore structure due to stresses induced by receding water meniscuses on drying.

2- Solvent replacement tends to preserve original pore structure.The table below shows the effect of solvent type in solvent replacement technique:

Sample no.

Heat drying with vacuum

Time of preheating vacuum treatment

solventTD(µm)

Pore vol At 0.1 µm

Pore vol At 0.01 µm

Total pore volume

A

20h,100˚c

0 Methanol 0.5 16 37.5 51B 5 Methanol 0.59 19 38.2 52C 16 Methanol 0.59 16 36 50.5D 24 Methanol 0.25 13.6 36 49H 0 Isopropanol 0.35 12 35 49.8J 5 Isopropanol 0.35 12 35 49.8L 16 Isopropanol 0.35 12 35 49.8M 24 Isopropanol 0.59 19 41.5 49.8(For CEMI)

Table (4-1)

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When Portland cement pastes are prepared with the same drying procedure, the porosity values found by mercury intrusion or helium pycnometry are the same. But this is different in case of pozzolana containing cement. Since values of porosity obtained by helium are confirmed by using methanol saturation, we can say that mercury can not occupy the entire space accessible to helium and methanol.When total porosity of pozzolanic cement is assessed by mercury intrusion, it turns out to be higher than that of Portland cement. The table below shows these results for natural pozzolana and containing cement:

samplePortland cement%

Blending component%

Porosity28 days curing 7 months curingRabid Slow Rabid Slow

CEM I 100 0 17 14.7 13.1 10.6Filler 70 30 17.8 21.4 15.3 13.8Fly ash 70 30 21.8 21.3 17.4 16.4Vizzini pozzolana

70 30 18.7 21.6 14.3 12.9

Qualiano pozzolana

70 30 20 18.8 11.3 10.7

Casteggio pozzolana

70 30 17.8 16.3 13.6 11.6

Barile pozzolana

70 30 17.7 17.9 13.5 12.7

Sengi pozzolana

70 30 17.5 19.3 13.4 34.2

Bacoli pozzolana

70 30 17.8 18.7 13.3 11.4

Table (4-2)

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As for silica fume and fly ash containing cement:

paste Age Total pore are

Av. Pore diameter

Bulk density

Skeletal density

porosity Permeability

Control 1 38.3 0.036 1.37 2.6 47.4 1.2×10-7

3 53.4 0.022 1.46 2.54 42.5 4.9×10-10

7 53.9 0.019 1.47 2.39 38.4 6.5×10-10

28 50.7 0.018 1.51 2.33 35 6.2×10-12

4515 1 28.8 0.045 1.43 2.65 46 1.1×10-7

3 48.4 0.026 1.4 2.48 43.6 2×10-8

7 50.4 0.023 1.4 2.32 39.7 1.3×10-8

28 50.7 0.02 1.5 2.39 37.4 1.3×10-11

4530 1 24.4 0.061 1.32 2.57 48.6 7.1×10-7

3 43.2 0.031 1.42 2.7 47.5 4.7×10-8

7 50.7 0.026 1.32 2.3 42.8 5.6×10-9

28 55.9 0.02 1.43 2.42 40.9 1×10-12

1015 1 32.9 0.041 1.37 2.54 46.3 6×10-8

3 43.3 0.028 1.41 2.46 42.7 6.4×10-9

7 53.9 0.022 1.42 2.43 42.1 6.1×10-10

28 55 0.019 1.47 2.36 37.9 2.9×10-12

1030 1 41 0.039 1.29 2.62 50.9 1.6×10-7

3 49 0.03 1.35 2.66 49.3 2.3×10-8

7 50 0.026 1.36 2.43 44.3 1.9×10-9

28 36.9 0.02 1.35 2.35 42.4 5.3×10-13

Table (4-3)What ever was the type of pozzolana, porosity decrease with time but it still higher than porosity of Portland cement. Porosity increases by increasing fly ash but decrease by increasing rice husk.Porosity of blended cement paste depends on method of determination through all range of porosities. Porosity measured by methanol or helium pycnometry appears to be lower than by mercury intrusion, as shown in figures below:

31

Figure (4-2)

Figure (4-3)

32

So, basically we can say that; Mercury porosity is higher than helium porosity Helium porosity is higher for oven dried samples than for solvent

replacementThe damage caused by mercury intrusion in fly ash containing pastes is demonstrated by subjecting samples to two following intrusions. Repeated intrusions showed that in Portland cements pores size distributions did not change much except for an increase in threshold diameter, but blended cement differs a lot.The figure here shows that curve has changed from convex to convex.

Figure (4-4)

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Since the two methods give comparable results with Portland cement pastes, it can be assumed that the pore structure of pozzolana cement pasties different and the pore system is more segmented.

4-2. Properties of pozzolana containing MortarsMechanical properties

1. Setting:Setting time does not change greatly from Portland cement when using natural pozzolana. As for fly ash, it delays initial and final setting times. Silica fumes prolong setting times but, it is usually used with plasticizers which make it difficult to differentiate the delay resultant by silica fume from the one of the admixtures.

2. Strength:Pozzolana starts reacting slowly with calcium hydroxide and initially behaves as an inert material diluting the Portland cement. Pozzolana accelerates early hydration of clinker after 8hours after mixing with water.Partial replacement of pozzolana for Portland cement reduce initial rate of hardening but at greater ages this situation is reversed and pozzolana cement can attain the same or even higher strength than Portland cement.The following figure shows that 30% replacement of fly ash can reduce strength by 50%, difference in strength decrease by time till it disappears or reverse sign.

Figure (4-5)

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The moment of recovery depend on fineness of Portland cement and pozzolana and activity of pozzolana. The effect of pozzolana on strength depends on:

Pozzolana content and typeThe figure below shows an optimum level of replacement which is dependent on type of pozzolana used.

Figure (4-6)The strength of pozzolana cement depends on characteristics of pozzolana used as shown in figure below.

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Figure (4-7) Particle size distribution of pozzolana

The figure below shows that the negative effect on strength increases with particle size and decrease with time only for fine fractions.

Figure (4-8)Grinding promotes activity of fly ash but if fineness exceeds certain limits compressive strength decrease instead. That is due to decrease in combined lime which is ascribed to decrease in permeability of paste which hinders mobility of ions.

36

Properties of Portland cementThe influence of 8fly ashes and 4portland cements on relative compressive strength.

Figure (4-9)Difference in strength between blended and Portland mortars have been attributed to different content of alkalis in Portland cements among other factors.

ShrinkageNormal percentage of pozzolana does not affect drying shrinkage or expansion in water. The following table shows that shrinkage in air for Portland cement and pozzolana cement is the same.

CementCuring period

7 28 90CEM I 32.5 427 755 890CEM I 42.5 396 733 873CEM I 52.5 453 842 1043CEM I 32.5 329 653 793CEM I 42.5 381 725 904CEM I 52.5 434 797 991CEM I 42.5 430 685 810CEM I 52.5 461 770 988

CEM IV 32.5 428 784 943CEM IV 42.5 420 743 915

CEM IV A 393 737 889CEM IV B 32.5 440 765 900CEM IV A 42.5 425 706 890

Table (4-4)

37

The next table shows that shrinkage of mortars is affected by the fineness of clinker more than by fineness of fly ashes.Fineness(cm2/g) Fly ash

contentCuring period

Clinker Fly ash 7days 28days 90days 1year 5years2540 0 430 500 650 750 750

2880 40 400 460 500 500 5508200 40 400 500 560 600 630

3580 0 500 650 780 1000 11002880 40 400 530 590 680 7208200 40 400 530 620 750 780

5130 0 700 870 1060 1340 14502880 40 460 590 720 840 8708200 40 440 590 720 840 870

Table (4-5)

4-3. Effect of pozzolana on durabilityDurability defines the suitability of concrete to preserve structural performance, fixed by designer, over the time; it plays an important role in determining the service life of the structure.Influence of environment ;

(1) H2O effect:Water can decompose any hydrated compound in cement and leach lime leaving a residue made of SiO2.xH2O,Al2O3.yH2O and Fe2O3.zH2O. The residue acts as a protective layer against leaching on account of the gel-like nature of its compounds.The rate of leaching is high for porous concrete in excess presence of water or its renewal. It slows down when concrete is compact and strong. Leaching increases porosity and permeability which decreases strength and durability. The methods for assessing resistance of leaching based on water percolation through more or less porous concrete followed by determining leached lime or loss of mass.The amount of leached lime by distillated water from porous pozzolana cement is less than released by Portland cement and decreases as pozzolana/clinker ratio increase as shown in the following figure.

38

Figure (4-10)

When compared to pozzolanic cement, Portland cement showed; Thicker corroded layer Diffuse porosity decreasing form the surface to the inside Deposit on the surface of gel like layer crossed by small channels

The mass loss of prism cured for28 days stored in soft water and brushed increase by substituting 30-40%of fly ash for Portland cement.That loss is related to the decrease in strength caused by partial replacement in initial setting period. Acid water increase rate of leaching, but pozzolanic cement shows better resistance than Portland cement as illustrated in the table below:

Mix compositionMix105 Mix109

OPC(kg/m3) 170 312Fly ash(kg/m3) 170Water/binder 0.35 0.6

28 days compressive strength

78.4 43.2

Cumulative mass loss(g/kg)Brushed

5.8 7.8

Un brushed 2.5 3.4Table (4-6)

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The reasons that hard pastes of pozzolanic cement are more resistant to leaching more than Portland ones are:

They contain 3-6%Ca(OH)2 compared to 20-22% of Portland cement They contain more calcium silicate hydrates The C/S ratio of C-S-H is lower They have lower permeability

(2)SO4-2 effect:

Sulfate can be dangerous to concrete due to expansive nature of them or the products of their reaction with cement. CaSO4 reacts on calcium aluminates hydrates forming expansive ettringite (3CaO.Al2O3.3CaSO4.32H2O)Na2SO4 react on calcium hydroxide forming gypsum which in presence of aluminates gives ettringite.MgSO4 react on all cement compounds forming Mg(OH)2 (brucite) and gypsum.Conditions enhancing formation of expansive compounds are:

Occurrence of both aluminates hydrates and calcium hydroxide, the following figures illustrate the positive effect of natural pozzolana

Figure (4-11)

40

Figure (4-12) Characteristics of mortar and concrete (strength, porosity and

permeability)The figure below shows the expansion of Portland cement mortars by increasing w/c ratio, i.e. by increasing porosity and permeability.

Figure (4-13) PH range, the range between 6-11.5 is less aggressive Volume/surface area ratio of concrete. In the figure below we can see

that positive effect by pozzolana is enhanced by increasing the size of the sample.

41

Figure (4-14)Na2SO4 attack; natural pozzolana increase the sulfate attack resistance of cement.Also artificial pozzolana improves sulfate resistance to the attack by sodium sulfate. The sulfate resistance of pozzolana increases as curing time increases. Pozzolana only delays the performance failure but not eliminate it. They can prolong the life expectancy of concrete as shown in the figure below.

Figure (4-15)The next figure shows the improvement in resistance to sulfate attack caused by increase cement dosage.

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Figure (4-16)Silica fumes increase resistance to sodium sulfate attack, the higher the replacement level the lower the expansion. The grade of silica play an important role, since 10% replacement of good silica fume are enough to keep expansion below0.1% while for the same level of protection 15% of poor quality silica fume replacement is required. The physical and chemical properties of 28 days fly ash and silica fume mortars are explained in the table below through the pore volume of both when immersed for one year.

w/c ratio

28 days 1year pore volumeComp. strength

Total pore vol

water 10% Na2SO4

10%MgSO4

Plain mortar

0.55 45.3 39.8-17.6 33.8 (11.1)

94.8 (83.3)

52.2 (36.1)

Fly ash 10% 0.54 37.1 22.4-23.6 26.3 (34.6)

25.8 (32.9)

30% 0.52 35.8 44.5-15.1 33.2 (15.4)

27.7 (20.9)

22.9 (38.4)

50% 0.5 23.8 42.8-16.5 38.6 (13.2)

19.9 (42.7)

70% 0.48 11.7 62.2-34.6 85.5 (10.6)

43.5 (19.5)

Si fume 5% 0.55 44.4 50.7-13.8 30.1 (11.6)

45.6 (28.9)

10% 0.54 45.1 36.1-11.6 44.7 (22.6)

46.8 (24.6)

22.4 (21.4)

20% 0.54 46.6 29-20.7 33.8 (17.8)

55.7 (57.6)

30% 0.53 50.2 28.4-21.1 17.8 (36.5)

27.2 (31.2)

68.6 (87.5)

Table (4-7)

43

Linear expansion, weight gain and sulfate consumption of concrete exposed to 5% sodium sulfate were strongly reduced when silica fume used in 10% replacement. Inter grounding of pozzolana with gypsum reduce the effect of sulfate attack more than when it is just mixed with clinker and gypsum.MgSO4 attack;It is considered to be more severe than sodium sulfate attack. Natural and artificial pozzolana can enhance resistance of mortars to magnesium attack but some times they can worsen the performance. That performance seems to be dependent on type of pozzolana used.OPC containing 25% of fly ash behaves like sulfate resisting in weak MgSO4 but it is of low performance in concentrated solutions.The table below shows the loss of strength and resisting properties in Portland and pozzolana mortars through time.Type of mortar

Type of cement

Compressive strengthMPa % of water cured samples90 d 180 d 1 y 2 y 90 d 180 d 1 y 2 y

Plain OPC 37.8 12.8 17.4 7 107 61 40 16SPC 36.7 20.2 8.5 116 61 23SRPC 40.7 36.6 33.9 32.2 110 93 83 72

15%Si fume

OPC 29.1 22.1 12 63 46 21SPC 36.3 20.4 12.5 99 48 29SRPC 46.8 17.7 11.7 103 39 23

Table (4-8)OPC= ordinary Portland cementSPC= slag Portland cementSRPC= sulfate resisting Portland cementLevel of effectiveness of pozzolana don't depend much on type of cement used, it depends more on level of replacement, the following figure prove that.

44

Figure (4-17)Influence of aggregates;Alkali-silica reaction; this reaction forms a more or less viscous gel made up of alkali- and alkaline earth silicates which tend to absorb water from the environment and expand.Conditions essential for alkali-silica reaction:

High alkali content of cement Only a part of aggregates is reactive High humidity

Influence of pozzolana; there were cases where pozzolanas were not effective in preventing expansion of alkali-silica reaction which is ascribed to insufficient quantity or poor quality of pozzolana. The expansion of mortars varies with the proportion of reactive aggregates and it reaches maximum at a certain level "Pessimum effect". The addition of pozzolana reduces this effect but some times give a similar effect as shown in the following figure.

45

Figure (4-18)Generally, partial replacement of high alkali cement with pozzolana produces great reduction in expansion. However, some fly ashes give a pessimum effect as shown in the figure.

46

Figure (4-19)This is not a general rule since in some fly ashes this peak doesn't appear as shown in the figure below.

Figure (4- 20)Addition of pozzolana increase total alkali content but the availability of these alkalis depends on progress of pozzolanic reaction.The next figure show that expansion reduction due to alkali-silica reaction depends on the source of pozzolana which when differ it varies specific surface area of pozzolana.

47

Figure (4-21)In conclusion, all laboratory tests and field experience have shown that pozzolana reduce expansion provided that replacement is sufficient.Factors reducing expansion

Lower permeability Lower alkalinity High alkali content Low portlandite content Low C/S ratio for C-S-H

48

Experimental techniques

49

Ch. (5): Experimental

5.1- Determination of free lime in pozzolana procedures

Reagents;

Solvent: One part by volume pure glycerol to 5 volumes absolute ethyl

alcohol.

Indicator: 0.18 g of phenol phthaline was dissolved in 2160 ml of the

previous mixed solvent.

Standard ammonium acetate titrante : 16 g dry crystalline ammonium

acetate was dissolved in 1 liter of distillated water.

Pozzolanas;

1- Standard silica fume

2- Standard Homra

Procedure

1- Sample preparation

To obtain CaO we burn Ca(OH)2 at 900˚c for 1 hour

To prepare testing samples we mix (8:2 lime : pozzolana) and cure them for

24 hours at 50˚c.

2- Standardization

0.5 g of freshly ignited CaO was placed in 200 ml Erlenmeyer flask, about 60

ml of glycerol-ethyl alcohol solvent were added.

A reflux condenser was fitted then the mixture was boiled for 5 – 20 minutes

and then titrated while still nearly boiled with ammonium acetate solution

until the pink color disappears. The boiling continued for 5-20 minutes and

the mixture titrated again, this process was continued till the free CaO content

does not exceed than 0.05 % after 2 hours boiling where no further pink

coloration appears.

50

3- Samples

Exactly 0.5 g of sample was put in 200 ml Erlenmeyer flask, 40 ml of

glycerol-ethyl alcohol solvent were added and proceeding as in

standardization of ammonium acetate solution .

5.2- Results and discussion

Percentage of free lime is calculated by the law:

Where: W1 weight of freshly ignited CaO (standard).

V1 ml of ammonium acetate required for ignited CaO.

W2 weight of sample taken

V2 ml of ammonium acetate required for sample.

No. 1 2 3

SampleFresh

ignited CaO

2g Silica

fume+8g CaO2g Homra+8g CaO

Results

V1 = 74.5 ml

V2 (Homra) = 65 ml

V2 (Si.fume) = 62.5 ml

In Homra

In silica fumes

Discussion:51

From the results shown the percentage of free lime after 24 h curing for (8:2 lime: pozzolana) sample is as followsPozzolana Homra Silica fumes%CaO 87.2% 83.8%

The higher percentage in case of using homra indicates that silica fume react with lime at a higher rate Then the pozzolanic reaction of silica fume is some what faster than that of homra.

List of tables

No. Table1-1 Cement types and uses1-2 Ingredients of blended cements2-1 Types of pozzolana

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2-2 Chemical composition of incoherent volcanic pozzolana2-3 Mineralogical composition of coherent volcanic pozzolana2-4 Chemical composition of tuffs2-5 Composition of the three layers in tuffs2-6 Mineralogical composition of transformed materials2-7 Chemical composition of diatoms2-8 Chemical composition of mixed origin pozzolana2-9 Chemical composition of bituminous fly ash(class F)2-10 Mineral composition of bituminous fly ash(class F)2-11 Chemical heterogeneity of fly ash (class F)2-12 Ash particles classification of class F2-13 Chemical composition of fly ash (class C)2-14 Mineralogical composition of fly ash (class C)2-15 Chemical composition of micro silica3-1 Pozzolana combination with lime

3-2Hydration products in pastes and excess water for pozzolana cement

3-3Nature and amount of hydrated compounds in excess water solution of pozzolana-lime mixture

4-1Effect of solvent in solvent replacement water removal of pastes on porosity

4-2Porosity results by mercury intrusion for Portland and blended cement

4-3Porosity results by mercury intrusion for silica fume and fly ash cement

4-4Comparison of shrinkage between Portland and pozzolana cements

4-5 The relation between shrinkage and fineness of cements4-6 Resistance of cements to water leaching

4-7The physical and chemical properties of 28 days fly ash and silica fume mortars

4-8Loss of strength and resisting properties in Portland and pozzolana mortars through time.

List of figures

No. Figure

2-1The relation between content of CaO and the position of maximum of X-ray in background

3-1Relation between specific surface area and pozzolana/lime ratio for different water content

3-2 Relation between amount of combined lime and pozzolana/lime

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ration3-3 Relation between amount of combined lime and time of curing3-4 Relation between temperature and rate of pozzolanic reaction3-5 Thermal treatment of pozzolana4-1 Effect of drying method on porosity and pore size distribution4-2 Difference in porosity measured by methanol or helium and that

measured by mercury4-3

4-4Damage caused by mercury intrusion in fly ash containing samples

4-5 The relation between compressive strength and time for mortars4-6 Effect of pozzolana content on strength of mortar4-7 The effect of pozzolana type on strength on mortar4-8 Effect of pozzolana fineness on compressive strength 4-9 Influence of Portland cement properties on mortar strength

4-10The amount of leached lime by distillated water from porous pozzolana cement and Portland cement.

4-11 Effect of occurrence of both aluminates hydrates and calcium hydroxide on formation of expansive compounds in concrete4-12

4-13 Variation of expansion rate according to w/c ratio4-14 Effect of size of sample on expansion of concrete4-15 Effect of pozzolana content on strength

4-16Improvement in resistance to sulfate attack caused by increase cement dosage

4-17 Effect of cement type on expansion4-18 Effect of pozzolana addition on expansion "pessimum effect"4-19 Pessimum effect in some fly ashes4-20 Fly ashes that don't give pessimum effect

4-21Expansion reduction due to alkali-silica reaction dependant on the source of pozzolana

References1. A.Komar

Chapter (V)- B- Hydraulic bindersBuilding materials and components, 135-185 (1979- second edition 1987)

2. LeaChapter (10)- Pozzolana and pozzolanic cements (Franc Massazza)Chemistry of cement and concrete, 471-602 ( 1998 )

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