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
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 properties. 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 works. These are largely adhesives consisting of a mixture of compounds of lime as their principal constituents. These are termed calcareous cements1. Cement 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 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. 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. 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. 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. 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.
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. Countries such as Britain, Spain, France and Argentina based on research results, have set standards for the inclusion of supplementary materials like limestone and other pozzolanic admixtures to OPC. For example, British Standards (BS 882) allow up to 15 % inclusion of limestone in OPC
