Determination of the Pozzolanic Properties of Olotu Marine Clay and Its Potentials for Cement Production

doi:10.4236/msa.2011.21008

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Materials Sciences and Applicatio ns, 2011, 2, 53-58

doi:10.4236/msa.2011.21008 Published Online January 2011 (http://www.SciRP.org/journal/msa)

Determination of the Pozzolanic Properties of

Olotu Marine Clay and Its Potentials for Cement

Production

Jide Muliu Akande1, Chinwuba Arum2, Fola Micah Omosogbe3

1,3Department of Mining Engineering, The Federal University of Technology, Akure, Nigeria; 2Department of Civil Engineering, The

Federal University of Technology, Akure, Nigeria

Email: [email protected], [email protected]

Received October 12th, 2010; revised December 16th, 2010; accepted December 31st, 2010.

ABSTRACT

The physical and chemical properties of marine clay at Olotu in Ilaje local government of Ondo State, Nigeria were

investigated. Some of the physical properties investigated include plasticity index, linear shrinkage and firing charac-

teristics (firing colour, shrinkage percentage, and water absorption capacity). The physical properties were determined

using X-ray diffractometry method. The chemical composition was determined using Atomic Absorption Spectroscopy

(AAS) method. All tests were carried out according to proced ures specified b y relevan t British and American Stand ards.

It was established that the physical and chemical properties were adequate to qualify it as pozzolanic material for ce-

ment production when compared with other pozzolanic materials and measured against relevant standards. The cement

produced was tested for compressive streng th and setting times and the results confirmed th e appropriaten ess of the use

of the clay as a pozzolana.

Keywords: Fineness, Spectroscopy, Compressive Strength, Physical Properties, Portland Cement

1. Introduction

As the need for buildings and similar facilities and the

requirement for improved quality of these facilities in-

creased in developing countries, the demand for Portland

cement also rose being the only cementitious product

used for construction in these countries. The high cost of

foreign exchange has been a major constraint in provid-

ing the needed schools, offices, communications infra-

structure and other vital facilities needed in most of the

African countries. There is therefore the need to search

for cheaper alternatives to Portland cement.

The production and use of alternative cement dates

back to the Roman days, and the remains of the great

buildings constructed with it are a testimony to its usage

dating back to antiquity. These alternative binding mate-

rials are known as pozzolanas. A pozzolana is a siliceous

and aluminous material which reacts with calcium hy-

droxide in the presence of water to form compounds

possessing cementitious properties at room temperature

and have the ability to set under water [1]. Pozzolanas

are classified as natural or artificial. Natural pozzolanas

may further be divided into two main groups as:

1) Those derived from volcanic rocks in which the

amorphous constituent is glass produced by fusion.

These include volcanic ashes and tuffs, pumice, scoria

and obsidian.

2) Those derived from rocks or earth for which the sil-

ica constituents contain Opal, either from precipitation of

silica from solution or from the remains of organisms.

Examples of these are diatomaceous earths, cherts,

opaline silica, and lava containing substantial amounts of

glassy component and clay which has been naturally cal-

cined by heat from flowing lava. In Africa, some of the

known sources of natural pozzolanas of volcanic origins

may be found in Cameroon, Cape Verde, Burundi,

Ethiopia, Tanzania, Kenya, Rwanda and Algeria.

Artificial Pozzolanas may be divided into two groups:

those of organic and those of inorganic origin. The most

important artificial pozzolanas of inorganic origin are

obtained from calcined clays and shales, calcined bauxite,

calcined bauxite-waste, calcined spent oil, calcined moler,

calcined gaize “fly ash” (pulverized fuel coal) and brick

powder (surkhi). Kaolinite is the mineral name for an

economic clay commonly called kaoline. It is a group of

clay minerals that consists of kaolinite, dickie, nitrite,

anauxite, halloysite and endellite. They are secondary

Determination of the Pozzolanic Properties of Olotu Marine Clay and Its Potentials for Cement Production

minerals formed by weathering hydrothermal alteration

or wall rock alterations of highly feldspathic rocks whose

compositions are only slightly different from each other,

especially in the stacking arrangement of their structures

[2]. The sources of artificial pozzolanas of organic origin

are ashes of rice husk, coffee hulls, coconut shells, sugar

cane bagasses and palm-nut shells and fibers. Investiga-

tions into the use of cocoa pod for pozzolana production

have not been concluded. Of these pozzolanas of organic

origin, rice husk ash has been well investigated and

documented [3]. This research is aimed at determining

the properties of Olotu marine clay in order to verify its

suitability as a pozzolana for the production of cement.

2. Materials and Method

2.1. Materials

The marine clay and periwinkle shell samples used in

this study were collected from Olotu, a town in Ilaje local

government, south western part of Ondo state, Nigeria.

Other materials include locally fabricated laboratory size

electric furnace for calcining the marine clay and peri-

winkle shell, a thermocouple which automatically con-

trols the heating and cooling of the furnace, a laboratory

size ball mill for milling the calcined materials and a set

of laboratory sieves. Other equipment used included the

Vicat apparatus for testing the setting time of cement and

a crushing machine for determining the compressive

strength of moulded cubes.

2.2. Method

2.2.1. Production Procedure

The samples of Olotu marine clay were moulded into

balls of about 30 mm in diameter and dried in the sun to

reduce the moisture content. At a temperature of 700˚C,

the dried clay was calcined in the electrically heated fur-

nace for about 3 hours. This temperature was maintained

with the aid of a thermocouple and a suction fan at the

exhaust. After 24 hours the calcined clay was pulverized

and milled in the ball mill and later sieved using a set of

laboratory sieves with sieve shaker to fines of 1.18 mm.

The periwinkle shell was heated at 750˚C for 1.75

hours in the furnace with the temperature controlled us-

ing the thermocouple, and the carbon dioxide gas (CO2)

pressure reduced or controlled by the suction fan at the

exhaust. The fan sucked out the emitted CO2 by the shell,

reducing the pressure in the furnace and thereby avoiding

re-carbonation of the quicklime produced. The dis-

charged quicklime was slaked by manually sprinkling

some quantity of water (55 liters per 200 kg i.e., 27.5%

of shell weight) on it. The slightly moist and hot slaked

lime was left to dry out and cool for 24 hours, after

which it was pulverized and milled in the ball mill and

then sieved through 1.18 mm mesh.

The processed materials were batched by weight in the

ratios 3:1 and 2:1 corresponding to three pozzolana to

one lime and two pozzolana to one lime [4,5]. Regrind-

ing of the mix was done in the ball mill to produce fines

of 125-106 microns (120-150 mesh) after sieving. The

Lime-Pozzolana Cement (LPC) was bagged in polyeth-

ylene-lined bag and ready for use.

2.2.2. Tests for Setting Time

The Vicat apparatus was used for the purpose of deter-

mining the setting time and standard consistency of the

lime-pozzolana cement in accordance with the provisions

of [6], with a needle diameter 1.30 mm and load 300 g.

The needle was released at the surface of the hydrated

cement paste at intervals until it penetrated only to a

point 5 mm ± 1 mm from the bottom of the mould. When

the paste attained this degree of stiffness, it was said to

have reached initial set. A second needle, similar to the

first but with an attached concentric ring was then used

to determine final setting time. This was reached when

the needle made an impression on the surface of the paste

but did not penetrate the 0.5 mm necessary for the ring to

mark the surface.

2.2.3. Compressive Strength Tests

2.2.3.1. Moulding and Testing of Cubes

Various cubes were made using 150 mm cube moulds.

Table 1 shows the mix proportions of the mortar used for

the cubes (A to C) cast from different cements as propor-

tions by weight of Cement: Sand: Water. A constant

volume of water was used [4].

Cubes A1 and A2 were produced from Ordinary Port-

land Cement (OPC) and served as control for B1, B2 and

C produced from Lime-Pozzolana Cement (LPC). The

compressive strengths of the cubes were obtained at ages

7, 14, 21 and 28 days. The densities of the cubes were

calculated when wet and when dry.

3. Results and Discussion.

3.1. Results

3.1.1. Physical Properties

The firing characteristics of Olotu clay are shown in Ta-

Table 1. Mortar mix proportions for different cements.

Cube mark Composition

OPC Sand Water

A1 1 3 0.6

A2 1 2 0.6

LPC Sand Water

B1.1 1 3 0.6

B1.2 1 2 0.6

B2.1 1 3 0.6

B2.2 1 2 0.6

(OPC:LPC) Sand Water

(7:3)

1 3 0.6

Determination of the Pozzolanic Properties of Olotu Marine Clay and Its Potentials for Cement Production

ble 2 while the results of its essential geotechnical index

properties are presented in Table 3.

3.1.2. Chemi c al Comp osition

The result of the analysis of Olotu marine clay for

chemical composition is shown in Table 4 while the

chemical composition of the periwinkle shells is shown

in Table 5.

3.1.3. Setting Time

The results of the tests for the setting times of the various

cements are presented in Table 6.

3.1.4. Compressive Strength

The result of the compressive strengths of mortar cubes

cast from the various cements, including their weights

and densities, is presented in Table 7.

3.2. Discussion of Results

3.2.1. Firing Characteristics

The moist samples were dark and light to dark grey in

colour but later exhibited colour change when fired. Two

groups of fired colours were obtained: reddish brown/

pinkish and buff colours. These colours showed depend-

ence on the amount of iron and titanium (as pigment)

oxides present. The clays with iron oxides between 2-3

percent give reddish brown and pink colour (Table 2).

This result is somewhat similar to those obtained by Og-

bukagu [7] for argillacious clays of Suthern Nigerian

sedimentary basin. It has been established [8] that clays

with iron oxide exceeding 2-3 percent usually give pink-

ish and/or reddish brown colour upon firing whereas,

Table 2. Firing characteristics of Olotu marine clay.

Sample

No. Moist

colour Firing

colour Shrinkage

(%)

Water

absorption

(%)

1. DG RB 17.23 13.50

2. LG CBU 14.50 11.40

3. DG P 13.63 13.34

4. DG RB 13.42 13.22

5. G C 12.57 12.58

Table 3. Some geotechnical index properties of Olotu ma-

rine clay.

Sample

No. Clay +

Silt (%) Sand

(%)

Plastic

Limit

(%)

Plasticity

Index Linear

Shrinkage (%)

1. 88.0 12.0 64.7 43.7 13.50

2. 82.0 18.0 52.5 35.4 11.38

3. 95.0 15.0 36.7 36.5 11.42

4. 86.0 14.0 58.7 39.3 11.60

5. 90.0 10.0 68.3 46.3 12.30

Table 4. Chemical composition of Olotu marine clay (%).

Sample SiO2Al2OFe

2O3TiO2 MgO CaO K2O NaOLOI

BH152.3012.713.441.02 0.38 2.55 0.30 0.5126.80

BH248.7318.523.460.86 0.51 2.42 0.41 0.4724.59

BH354.2024.022.551.05 0.22 1.97 0.47 0.6414.88

BH451.4023.652.851.20 0.40 2.51 0.38 0.5217.09

BH545.6622.623.851.10 0.31 2.35 0.43 0.4623.22

Table 5. Chemical composition of periwinkle shell (%).

SiO2AL2O3Fe2O3CaOMgO NaO LOITotal

1.18 0.51 0.35 66.13 0.02 0.11 33.5699.86

Table 6. Experimentally determined setting times of differ-

ent cements.

Cube mark IST (Hr) MFST (Hr)

A 0.72 10.25

B1 1.38 16.08

B2 1.20 15.50

C 1.00 13.75

those with lower percentage of iron oxide develop

creamy, whitish or buff shades. In the present work,

about two of the samples developed cracks on firing. It

was observed that those samples with high content of

coarser material have this property while those with high

content of fine material developed no cracks on firing.

3.2.2. Geotechnical Index Properties

Table 3 contains the results of the geotechnical index

property tests. All the clay samples are fine grained,

characterized by high proportions of clay plus silt frac-

tions, the rest of the material being considered as sand.

Close examination of the sand particles revealed that

they were made up of a mixture of quartz and iron grains.

These were as a result of tropical weathering of rocks.

The clay is very plastic. This property reflects in the

narrow range of the plasticity index (35.4-46.3), which is

attributed to very low percentage of sand and significant

amount of clay and silt. These two physical properties

are responsible for high linear shrinkage values (11.38

-13.50%) obtained. It could be inferred that the higher

the plasticity, the higher the percentage shrinkage and the

higher the clay contents.

3.2.3. Chemi cal and Mi neralogical Comp o s i tion o f

Olotu Marine Clay

The clay contained some amount of lime (CaO), alkali

and magnesia oxides less than 1%. The low amount of

sodium oxide indicates low proportion of montmorilonite

in the samples and the low amount of potassium oxide

indicates low amount of illite present.

Determination of the Pozzolanic Properties of Olotu Marine Clay and Its Potentials for Cement Production

Table 7. Compressive strength of mortar cubes.

Compressive strength (MPa)

Cube

mark

Wet weight

(kg)

Density

(kg/m3)

Dry weight

(kg)

Density

(kg/m3) 7 days 14 days 28 days

7.51

7.56

7.43

2225

2240

2201

6.41

6.42

6.39

1902

1893

1899

6.91

7.11

7.02

9.96

10.06

10.18

15.40

15.41

15.42

7.60

7.58

7.62

2252

2245

2258

7.23

7.24

7.22

2142

2143

2139

10.10

11.11

11.12

14.50

14.60

18.15

18.13

18.11

B1.1

7.28

7.32

B1.2

7.37

7.38

7.35

2157

2168

2183

2186

2177

6.84

6.82

6.86

6.94

6.98

6.95

2026

2021

2032

2056

2068

2059

3.76

3.89

3.77

4.75

4.74

4.76

5.60

5.54

5.56

7.32

7.30

7.28

7.83

7.81

7.79

10.01

10.03

10.05

B2.1

7.40

7.42

7.38

B2.2

7.52

7.53

7.51

2192

2198

2186

2228

2281

2225

6.96

6.98

6.94

6.98

7.10

6.95

2062

2063

2056

2068

2077

2059

2.99

2.13

2.17

2.91

2.96

2.92

2.90

3.01

3.03

4.40

4.20

4.02

4.60

4.63

4.66

5.66

5.64

5.62

7.45

7.58

7.42

2207

2216

2198

7.02

7.04

7.03

2080

2085

2082

5.33

5.31

5.24

8.55

8.50

8.45

12.38

12.40

12.44

The X-Ray Diffraction (XRD) anaysis showed that

kaoline was the main clay mineral present in the sample.

It is recognized on the diffractograms at 2θ values of

26.60, 50.12, 20.13 and 68.08 (Figure 1). Quartz (60.03,

54.05, 36.30 and 12.40) is the principal non-clay mineral

in all the samples. The illite mineral appears at values

70.50, 72.50 and 76.80. The kaolinite and quartz peaks

are the most prominent on the diffractogram. Kaolinite is

the dominant clay mineral in the deposit and quartz is the

main subsidiary non-clay mineral detected from the XRD

trace.

3.2.4. Chemical Composition of Periwinkle Shell

Analysis of periwinkle shells presented in Tabl e 5 shows

a large percentage of CaO, which is a common charac-

teristic of shells. Its low magnesia content is a proof that

it possesses the general properties of calcium limes [9].

This is one of the criteria that qualified it as source of

lime in this research work.

3.2.5. Setting T i me of LPC

From the results of the tests for setting time shown in

Table 6, the times for LPC (B1) are longer than that of

Portland cement but still within the limit specified by BS

12 [10]. The longer times of the LPC are due to low

fineness of the materials compared with Portland cement.

The water content of the paste is another factor that af-

fects the setting time of cements. The higher the water

content of the paste, the longer it will take for the hydra-

tion product to form a structure with the chosen resis-

tance to penetration. Water to cement ratio of 0.60 tested

in Britain and favored in other European countries and in

USA is adopted in this work: Table 1 [4,10]. The factors

put together contributed to the differences shown in Ta-

ble 6. As shown in the table, the initial setting time of C

is low compared to those of B1 and B2. This is as a result

of the presence of OPC which boosted the hydration

process.

3.2.6. Compressive Strength of LPC

Table 7 shows a high positive correlation between the

density of a cube and its compressive strength. It shows

that the higher the density the higher the compressive

strength of the cube.

The major factor responsible for variations in strength

between group A and B is the variation in silicate content.

Group B1 has higher strength than B2 because the ce-

ment has the proportion of silicates needed for good

strength and so preferred to B2. Figure 2 illustrates the

variation in strengths of cubes made from different ce-

ments, with B1 having a steady increase in strength after

the seventh day.

4. Conclusions

From the results of this work the following conclusions

are apt.

1) The clay exhibits properties that qualify it as poz-

zolanic material for cement production, having 66.5% of

the oxides of silicon, aluminium and iron and 2.36% of

Determination of the Pozzolanic Properties of Olotu Marine Clay and Its Potentials for Cement Production 57

Figure 1. X-ray diffraction pattern of Olotu marine clay.

B1.1

B1.2

B2.1

B2.2

Compressive strength (MPa)

07th14th 28th

Figure 2. Relationship between the age of mortar and its compressive strength, for different cements.

calcium oxide in line with the recommendations of the

American Society for Testing and Materials (ASTM).

2) The delay in the setting times of the lime pozzolana

cements is as a result of its low fineness compared with

Portland cement.

REFERENCES

[1] Annon, “Pozzolana,” 2010. http://en.wikipedia.org/wiki/

Pozzolana.

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Vol. 3, No. 1, 2006, pp. 192-199.

[3] A. A. Hammond, “Manufacture and Use of Lime and

Alternative Cements in Africa,” In: N. Hill, F. Holmes

and D. Mather, Eds., Lime and Other Alternative Cements,

Intermediate Technology Publication Ltd., London, 1992,

pp. 35-45.

[4] W. B. Balu, “Research on Development of Alternative

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Determination of the Pozzolanic Properties of Olotu Marine Clay and Its Potentials for Cement Production

[5] P. H. Nalk, “KVIC Technology in the Production of Lime

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[6] BS 1881: “Testing Concrete, Part 131: Methods for Test-

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and Properties,” A. Wheaton and Co. Ltd., Exeter, 1983.

Notation

OPC Ordinary Portland Cement

LPC Lime Pozzolana Cement

C Cream

CBU Cream Buff

DG Dark Grey

G Grey

LG Light Grey

P Pinkish

RB Reddish Brown

IST Initial Setting Time

MFST Maximum Final Setting Time