ABSTRACT
The study was carried out on the comparative analysis of Portland cement in Southwestern Nigeria. The characterization and classification of cement is based on the determination of its chemical composition and physico-mechanical properties. The set of standards used for this project included the American Society for Testing and Materials (ASTM) and British Standards Institution (BSI) standards. Titrimetric/gravimetric methods of analysis were used. Four major cement samples using various physico-chemical methods were analyzed; two locally manufactured and two imported. Results of all the analysis showed that the locally produced cements, i.e., Elephant and Ashaka, differ in their physico-mechanical properties from the international ASTM and BSI standards. They are better used for structures involved with low load carrying capacities. The Burham cement matched well both in its chemical and physico-mechanical properties and thus can be subjected to structures involved with loading. Dangote cement needs to be further investigated upon. The developed assessment technique based on comparative analysis of ASTM and BSI standards with the technical qualities of the local cement brands can be used to control product quality during manufacturing of cement.
TABLE OF CONTENTS
ABSTRACT
CHAPTER ONE
1.0 INTRODUCTION
1.1 Objective of Study
1.2 Scope of study
1.3 Significance of Study
CHAPTER TWO
2.0 LITERATURE REVIEW
2.1 Manufacture of Portland cement in South-West, Nigeria
2.1.1 Raw materials
2.2 Methods of cement manufacturing
CHAPTER THREE
3.0 RESEARCH METHODOLOGY
3.1 Chemical Analysis by Conventional Method
CHAPTER FOUR-
Discussion of Results
CHAPTER FIVE
Conclusion
References
CHAPTER ONE
1.0 INTRODUCTION
Ordinary Portland Cement (O. P. C): a substance which binds together the particles of aggregates (usually sand and gravel) to form a mass of high compressive strength concrete. It is a combination of limestone or chalk with clay mixed in a proportion depend on the type of cement desired. Portland cement is the most common type of cement generally used around the world because it is a basic ingredient of concrete, mortar, stucco e.t.c. if a fine powder is produced by grinding Portland cement clinker more than 90 %, a limited amount of calcium sulphate which shall consist at least two-thirds by mass of calcium silicates (3CaO.SiO2). The remainder consisting of aluminum and iron containing clinker phases and other compounds. The ratio of CaO to SiO2 shall not be less than 2.0. The magnesium oxide content (MgO) shall not exceed 5.0% by mass. Portland cement as the cement that only harden by reacting with water but also forms a water-resistant product. Produce by pulverizing clinker consisting one or more of the form of calcium silicates, usually containing one or more of the calcium sulphate (diameter 0.2 – 1.0 inch (5 – 25mm), the low cost and wide spread availability of the limestone, shales and other naturally occurring materials make Portland cement one of the lowest – cost materials widely use over the last century throughout the world. (Wikipedia, the free encyclopedia, 2011).
Cements may be defined as adhesive substances capable of uniting fragments or masses of solid matter to a compact whole (Ghosh 1983). Cement functions by forming a plastic paste when mixed with water, which develops rigidity (sets) and steadily increases in compressive strength (hardness) by chemical reaction with the water (hydration). When a material increases in strength even when stored under water after setting it, the material is said to be hydraulic (Lea 1970).
This definition includes organic polymer-based cements which are used as adhesive, binders for aggregates used as hardening patching materials for damaged roads and bridge decks. However, the use of this organic based cement is limited due to its expensiveness as compared to the use of inorganic cements among which Portland cement is pre-eminent.
The properties of the final products of Portland cement in South-West, Nigerias are dependent on the chemical and morphological composition of clinker, gypsum and other additives introduced during the process of grinding. Changes in cement properties could occur during subsequent storage. Since the cement quality can be overwhelmingly dependent on the quality of clinker, it therefore means that any consideration of its characteristics requires a basic understanding of the factors that control the clinker quality and clinkerization process (Bye 1983).
1.1 Objective of Study
Because of the complexity of the factors influencing the rate of hydration and the hydraulics of cement, the assessment of cement classification and quality relies on direct performance tests. It can be seen from the literature that the values obtained for the basic composition, physical properties, etc., are particularly method dependent, so that a prescribed procedure must be followed and named when referring to the results obtained. This is presently not the case in the assessment of the various brands of cement in the country.
The major objectives of study therefore are:
1. Develop a standard specification method based on the chemical composition and physical characteristics of the Nigerian cement.
2. Develop a classification guideline for purchaser and users by specifying requirements on primary properties of the Nigerian cement influencing its quality and areas of application.
1.2 Scope of study
A preliminary survey on the different types of cement available in Nigeria was done and their relative availabilities considered.
These are as follows:
(i) Sokoto cement;
(ii) Ashaka cement;
(iii) Benue cement;
(iv) The West African Portland cement;
(v) The Nigerian cement, Nkalagu;
(vi) The Calabar cement company, Calcemco.
The imported cements were also considered, namely, Dangote cement and Burham cement.
Due to the skeletal operation and in some cases complete shut down of some indigenous cement companies, only 2 locally produced cements were available at the time of study.
Parameters measured include:
1. The bulk chemical composition of the cement. The cement was analyzed to determine the percentage composition of SiO2, CaO, Fe2O3, Al2O3, MgO, SO3, etc.;
2. Particle size composition of the cement;
3. Setting time of the cement;
4. Compressive strength of the cement;
5. Soundness of the cement;
6. Consistency of the cement.
1.3 Significance of Study
BSI (1978) protects the purchaser of cement by specifying requirements for those properties primarily influencing its quality. It is important that the Nigerian cement conforms to the set of internationally required standards.
In practice, cement structure durability, i.e., resistance to aggressive agents, is determined largely by concrete permeability and it is influenced by the efficiency with which cement hydration products fill the void between the grains of aggregates. Poor conformity of structures to established guidelines leads to the development of their degradation. This has necessitated investigations into the basic raw materials compositions, the finished products and other factors that could ensure longer service life for cement-based structures.
Therefore, with the present socioeconomic development and the envisaged technological advancement, the increased demand for cement cannot be overemphasized. It has become necessary, therefore, to characterize the available cement and effectively determine the area of optimal application.
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Item Type: Project Material | Size: 43 pages | Chapters: 1-5
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