ANALYSES OF SOME CEMENT BRANDS IN THE NIGERIAN MARKET AND OPTIMIZATION OF LIMESTONE CONTENT OF LIMESTONE COMPOSITE PORTLAND CEMENT

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TABLE OF CONTENTS

Title                                                                                                                           i

Certification                                                                                                 ii

Dedication                                                                                                                iii

Acknowledgements                                                                                            iv

Table of contents                                                                                           v

Table  of abbreviations                                                                                           x

List of figures                                                                                              xi

List of tables                                                                                                xii

Abstract                                                                                                           xiv

1.0                     Chapter one: Introduction                                         1

1.1                     The nature of cement                                                          1

1.2                   World cement production and consumption                 1

1.3                   Cement production in Nigeria                                                            2

1.4                     Limestone composite cement                                             2

1.5                   Statement of the problem                                               3

1.6                     Significance of the study                                                   3

1.7                     Aims and objectives of the study                                   4

1.8                     Scope of the study                                                         4

2.0                     Chapter two: Literature Review                                  6

2.1                   History of cement production                                               6

2.1.1                  Production of Portland cement                             6

2.1.2                  Sources of raw materials for cement manufacture in Nigeria       7

2.2                   Chemical composition of raw materials for cement production      8

2.2.1                  Limestone                                                        8

2.2.2                  Clays                                                                            10

2.2.3                  Minor and trace components                                  12

2.2.3.1               Magnesia, MgO                                                           12

2.2.3.2               Alkalis                                                               13

2.2.3.3               Sulphur                                                               13

2.2.3.4               Phosphorus                                                                  13

2.3                     Types of Portland cement                                 14

2.3.1                  Type 1                                                                      14

2.3.2                  Type 2                                                               14

2.3.3                  Type 3                                                                      14

2.3.4                  Type 4                                                                               15

2.3.5                  Type 5                                                                                15

2.3.6                  Other types of cements                                                 16

2.3.6.1               Coloured cements                                                                   16

2.3.6.2               Air entrained cements                                             16

2.3.6.3               Masonry cements                                                           16

2.3.6.4               Water proof cements                                                        16

2.3.6.5               Hydrophobic cements                                                  17

2.3.6.6               Oil wel            l cements                                                      17

2.3.6.7               Slag cements                                                                        17

2.3.6.8               High alumina cements                                              17

2.4                     Composition of Portland cement                                      18

2.5                     Estimation of clinker composition                                18

2.6                     Setting of Portland cement                                               19

2.7                     Manufacture of Portland cement                                    20

2.7.1                  Pre-blending of raw materials                                      20

2.7.2                  Heat treatment                                                                    22

2.7.3                  Clinker cooling and grinding                                      29

2.8                     Properties of Portland cement                                             30

2.8.1                  Fineness                                                                                 30

2.8.1.1               ASTM C 115: Fineness of Portland cement by the turbidimeter                   30

2.8.1.2             ASTM C 204: Fineness of hydraulic cement by air permeability apparatus   31

2.8.2                  Soundness                                                    31

2.8.3                  Setting time                                                                   32

2.8.4                  Strength                                                                34

2.8.5                  Loss on ignition                                                                 35

2.8.6                  Specific gravity                                                          35

2.8.7                  Heat of hydration                                                          35

 2.9                    Environmental impact                                              36

2.9.1                  CO2 emissions                                                         36

2.9.2                  Heavy metal emission into the atmosphere                       36

2.9.3                  Alternative fuels and by product materials                  36

2.10                   Cement in Nigeria                                           37

2.11                   Blended cements                                                         39

2.12                 Supplementary materials used in the manufacture of blended cements         40

2.12.1              High calcium fly ash                               40

2.12.2              Ground granulated blast furnace slag                                     40

2.12.3              Condensed silica fume                                                40

2.12.4              Rice husk ash                                                                         41

2.12.5              Volcanic ash                                                                 41

2.13                 Benefits of blended (composite) cement                      41

2.13.1              Economical benefit                                                          41

2.13.2              Technical benefits                                                  41

2.13.3              Environmental benefits                                                 42

2.14                 Limestone as a supplementary material in blended cement production         42

2.15                 Effect of limestone on properties of Portland cement          43

2.15.1              Particle size distribution and fineness                              43

2.15.2              Consistency                                                                            44

2.15.3              Hydration                                                                      45

2.15.4              Setting                                                                           50

2.15.5              Compressive strength                                                                 50

2.16                 Limestone reactions in limestone cements                           51

2.17                 Effect of limestone on concrete properties                     52

2.17.1              Workability                                                                       52

2.17.2              Sulphate resistance                                                          53

3.0                   Chapter three: Experimental                                          56

3.1                   Materials and methods                                                      56

3.1.1                Materials                                                              56

3.1.2                Reagents                                                                          56

3.1.3                Apparatus                                                                         56

3.1.4                Material sampling and sample preparation                   57

3.2                   Methods                                                                            57

3.2.1                Analysis of limestone                                                    57

3.2.1.1             Determination of calcium carbonate in limestone                   57

3.2.1.2             Determination of lime in limestone                                 57

3.2.1.3             Determination of loss on ignition                             57

3.2.2                Analysis of gypsum                                                 57

3.2.2.1             Determination of sulphite (SO3)                               57

3.2.2.2             Determination of gypsum purity                                            58

3.2.3                Analysis of clinker                                                            58

3.2.3.1             Determination of loss on ignition (LOI) and sulphite (SO3) of clinker          58

3.2.3.2             Determination of silica in clinker by baking method         58

3.2.3.3             Determination of iron (III) oxide and aluminium (III) oxide

in clinker by EDTA titration                                                                           59

3.2.3.4             Determination of calcium oxide in clinker by EDTA titration                       59

3.2.3.5             Determination of free lime in clinker by hot ethylene glycol method            59

3.2.3.6             Estimation of clinker constituents using Bogue’s formulae                           60

3.2.4                Preparation of Laboratory composite cements                                               60

3.3                   Physical analyses of cements                                              60

3.3.1                Determination of water demand and consistency      61

3.3.2                Determination of setting time                                 61

3.3.3                Determination of soundness                                    61

3.3.4                Determination of cement residue (fineness) using sieve method                   62

3.3.5                Determination of cement surface area using air permeability method            62

3.3.6                Determination of compressive strength                        62

3.4                   Chemical analyses of cements                       64

3.5                   Quality control and statistical treatment of data             64

4.0                   Chapter four: Results and discussion            65

4.1                   Results                                                                             65

4.2                   Discussion                                                                  72

4.2.1                Clinker parent sample                                                     72

4.2.2                Ordinary Portland cement (OPC)                               73

4.2.3                Effect of added limestone on chemical composition of LCCs                      74

4.2.4                Effect of added limestone on particle size and surface area                          76

4.2.5                Effect of added limestone on soundness of Portland cement             78

4.2.6                Effect of added limestone on setting time and consistency

of Portland cement                                                                                         78

4.2.7                Effect of added limestone on strength development of Portland cement     82

4.3                   Comparison of some analysed market brands of cements MBCs                  83

4.4                   Conclusion                                            86

4.5                   Recommendations                                                    86

4.6                   Contribution to knowledge                                                       86

References                                                                                       87

Appendices                                                                                    93

TABLE OF ABBREVIATIONS

Abbreviations/Symbols Definition
ASTM American standard for testing and materials
C2S Dicalciumsilicate
C3S Tricalciumsilicate
C3A Tricalciumaluminate
C4AF Tetracalciumaluminoferrite
EDTA Ethylenediaaminetetraacetic acid
LCC Limestone composite cement
LOI Loss on ignition
LSPC Limestone Portland cement
MBC Market brands of cement
OPC Ordinary Portland cement
UNICEM United Cement
WAPCO West African Portland Cement Company
XRF X-ray florescence

LIST OF TABLES

 2.1                  Physical properties of limestone                                         8

2.2                   Classification of limestone deposit                           9

2.3                   Chemical composition of some limestone samples            

2.4                   Clay members showing variation in components                   10

2.5                   Physical properties of clay minerals                                            11

2.6                   Chemical composition of clay samples                                 11

2.7                   Chemical composition of corrective additives used in the production of Portland cement                                                                                       12

2.8                   Attack on concrete by soils and waters containing various sulphate concentrations                           15

2.9                   Clinker mineral content estimated by Bogue’s method and

microscopic analysis                                                                                        19

2.10                 Theoretical heat of hydration of clinker constituents    20

2.11                 Effect of calcite grain size on dissociation of limestone        26

2.12                 Temperature profile of various clay minerals                      28

2.13                 ASTM C 150 specified set times by test method          33

2.14                 Grinding parameters of limestone, natural pozzolana and fly ash blended cements at 15 percent addition and compressive strength values of strength values of samples prepared using cement types    44

2.15                 Sulphate resistance of cement with limestone additions              54

2.16                 Effect of 30 percent filler based on type and fineness on weeks to       failure of mortar bars in 5 percent sodium sulphate                                        55

3.1                   Composition of limestone composite cements (LCCs)         61

3.2                   Particle size distribution of standard sand used for preparation of mortar for determination of compressive strength                                     64

3.3                   Mixer speed during mortar production             64

4.1                   Mean values of total carbonate and lime content (%) and loss

on ignition of limestone parent sample                                                           65

4.2                   Mean sulphite content and purity of gypsum                         65

4.3                   Mean chemical and mineral parameters of clinker parent sample                   66

4.4                   Mean chemical and physical characteristics of OPC         67

4.5                   Mean values of chemical composition of ordinary Portland

cement (OPC) and limestone composite cements (LCCs)                              68

4.6                   Effect of added limestone on fineness of Portland cement                           69

4.7                   Mean values of soundness of Portland cement       69

4.8                   Mean setting times and consistencies of Portland cement      70

4.9                   Mean compressive strengths of limestone composite cements (LCCs)          71

4.10                 Mean range of chemical and physical parameters of some

 analysed market brands of cement                                                                72  

LIST OF FIGURES

 2.1                  Schematic presentation of reactions in the kiln at various temperatures        23

 2.2                  Le Chatelier test apparatus                                          32

 2.3                  Vicat test apparatus for setting time                           33

 2.4a                Compressive strength testing machine                        34

 2.4b                Prism mortars for compressive strength test                    34

2.4c                 Prism after fractured by load                                                35

2.5                   Schematic presentation of rates of heat evolution             47

2.6                   Heat evolution curves of ordinary Portland cement

blended with limestone                                     49

4.1                   Effect of limestone addition on loss on ignition of Portland cement             74

4.2                   Plot of freelime against % added limestone in Portland cement                    75

4.3                   Plot of sulphite against % added limestone in Portland cement                    75

4.4a                 Plot of residue retained on 90µm and 180µm against

% added limestone in Portland cement                                                          77

4.4b                 Plot of surface area of Portland cement against % added limestone in Portland cement                                         77

4.5                   Plot of consistency of Portland cement against % added limestone in Portland cement                                     81

4.6                   Plot of setting times of Portland cement against % added limestone in Portland cement                                   81

4.7                   Plot of strength development of Portland cement against

% added limestone                                                                                         83

4.8                   Effect of added limestone on strength of cement                83

ABSTRACT

Clinker, gypsum and limestone were obtained from an indigenous cement manufacturing company. The clinker and gypsum were ground together to produce ordinary Portland cement (OPC) which served as reference cement. Limestone composite Portland cements containing 5, 10, 15, 20, 25 and 30 % limestone were prepared by adding limestone to the OPC. Two foreign and two local brands of cement were purchased from the local market in Gboko, Benue state. The cement samples were subjected to chemical and physical tests using standard methods of analyses. Data were analysed using SPSS version 18 to compare the experimental, market and standard (OPC) cements. Analyses of clinker showed the following % composition: Silicon dioxide (20.23), alumina (6.29), ferrite (3.30), lime (65.48), sulphite (0.79), loss on ignition (2.17), free lime (0.87). The litre weight was 1274g/L. Percentage compositions of limestone were: total carbonate (91.08), lime (51.00) and loss on ignition (40.21). Percentage compositions of gypsum were: sulphite (42.31) and purity (90.97). Analysis of OPC showed the following percentages: silicon dioxide (17.75), alumina (6.09), ferrite (3.41), lime (64.62), sulphite (2.72), loss on ignition (1.50), free lime (0.88), particle size [45 micron (21.73), 90 micron (3.33) and 180 microns (1.33)], Blaine 297m2/kg; soundness 1.67 mm; consistency 27.97, Vicat plunger penetration 5.70 mm; initial setting time 107.33 mins; final setting time 180.67 mins; 2 days strength 26.27 MPa; 7days strength 31.07 MPa and 28 days strength 36.20 MPa. Analysis of various limestone composite Portland cement (%) were: silicon dioxide (17.00-17.64), alumina (5.99-6.08), ferrite (3.12-3.37), lime (64.70-64.97), sulphite (2.27-2.68), loss on ignition (3.69-13.25), free lime (0.55-0.83), particle size [45 micron  (19.87-30.33), 90 micron (2.13-5.93) and 180 microns (0.53-2.40)], Blaine (316-413) m2/kg, soundness (0.67-1.17) mm, consistency (24.80-27.60), Vicat plunger penetration (5.33-6.00) mm; initial setting time (115.33-126.00) mins, final setting time (183.00-229.33) mins, 2 days strength (17.28-25.00) MPa, 7 days strength (22.68-32.07) MPa and 28 days strength (28.47-34.77) MPa. Analysis of brands of Portland cement (%) showed: silicon dioxide (17.69-17.93), alumina (5.99-6.06), ferrite (3.25-3.30), lime (64.45-64.85), sulphite (2.70-3.46), loss on ignition (3.32-6.60), free lime (0.36-1.73), particle size [90 microns (0.93-7.07) and 180 microns  (0.00-0.80)], Blaine (283-394) m2/kg, soundness (0.67-1.17) mm, consistency (26.27-28.90), Vicat plunger penetration (5.33-6.00) mm, initial setting time (105.33-125.33) mins, final setting time (184.67-191.33) mins, 28 days strength (41.62-50.56) MPa. Statistical analysis revealed that OPC, limestone composite Portland cement containing 5-15 % added limestone and market sampled Portland cement brands all satisfied NIS specifications (28 days strength ≥32.5 MPa, soundness ≤ 10 mm, sulphite ≤ 3.5 %, plunger penetration 5-7 mm and initial setting time ≥ 75 mins) for Portland cement. This indicates that limestone composite cement containing not more than 15 % added limestone could be used for construction work without fear of failure or building collapse.

CHAPTER ONE

1.0 INTRODUCTION

1.1The Nature of Cement

Cement is the widest known building material in the civil industry. Cement is a substance used to bind solid fragments or masses of solid matter together to form one whole substance for the purpose of building, for example in making building blocks and concrete. By this definition the term cement embraces a large number of different substances having adhesive property. However popular use of the term cement has been restricted to adhesives used to bind stones, bricks, tiles etc in the construction of buildings and other civil works1. These are largely adhesives consisting of a mixture of compounds of lime as their principal constituents. These are termed calcareous cements1. Cements of this kind are finely ground powders which when mixed with water set into a hard mass. Setting and hardening result from hydration, which is a chemical combination of the cement compounds with water. As a result of their hydrating properties, constructional cements, which set and harden in the presence of water, are called hydraulic cements. Among these is Portland cement 2. Cement is applied as mortar and/or concrete. Mortar is used in binding bricks, blocks and stones in walls. Concrete is used for large variety of constructional purposes which include road construction and dams. Cement application as mortar or as concrete has helped in solving the durability needs of infrastructure such as houses and offices, roads, bridges etc.

1.2 World Cement Production and Consumption

The need for modern housing has generally increased the demand for cement. Consequently, cement production has grown exponentially over the years. In 2002, the world production of hydraulic Portland cement was 1,800 million metric tons. The three top producers were China with 704 million tons, India, with 100, and United States of America, with 91 million metric tons. These three countries produce about half the world’s total production 3. In 2005, China led with 43.46 percent followed by India producing 6.38 percent, then United States of America with 4.38 percent. For the past 18 years, China has consistently produced more cement than any other country in the world 3. This explains why China has the highest carbon dioxide emission in the world. In 2006 it was established that China manufactured 1.24 billion tons of cement which was 44 percent of the world total cement production 5. Demand for cement in China is expected to advance by 5.4 percent annually and this exceeded 1 billion tons in 2008. Cement consumption in China is expected to hit

44 percent of global demand and China will remain the world’s largest national consumer of cement by a large margin 6.

As the demand for cement increased over the years different types of Portland cement evolved in order to meet the demand. Type 1 or ordinary Portland cement (OPC) is the best cement. It has the highest strength, but it is expensive. Therefore cheaper cements of less strength or quality have been produced. These cements differ in their properties due to the various supplementary materials added to the raw materials, namely; limestone and gypsum. Examples of these supplementary materials include fly ash, pozzolana, slag, condensed silica fume, volcanic ash, rice husk ash, and limestone 7. Countries such as Britain, Spain, France and Argentina based on research results, have set standards for inclusion of supplementary materials like limestone and other pozzolanic admixtures to OPC 7. For example British Standards (BS 882) allows up to 15 % inclusion of limestone to OPC 8.

1.3       Cement Production in Nigeria

ANALYSES OF SOME CEMENT BRANDS IN THE NIGERIAN MARKET AND OPTIMIZATION OF LIMESTONE CONTENT OF LIMESTONE COMPOSITE PORTLAND CEMENT