1.1 Introduction
Cement is defined as a finely ground inorganic material which, when mixed with water, forms a paste that sets and hardens by means of hydration reactions and processes, and which, after hardening, retains its strength and stability over time. The global demand for cement continues to grow due to rapid urbanization, industrialization, and the development needs of emerging economies (Hewlett and Liska, 2019). Cement is a key construction material widely used in the building and infrastructure sectors due to its binding properties, strength, and durability. It is primarily composed of clinker, which is produced from raw materials such as limestone, clay, iron ore, and gypsum through a high-temperature manufacturing process. However, the traditional raw materials used in cement production are increasingly becoming unsustainable. Their extraction is energy-intensive, contributes significantly to greenhouse gas emissions, and results in the depletion of natural resources.
This chapter will address the background information that motivated this study, the challenges that prompted it, its aim, and its objectives as a preface to subsequent sections of the study. Additional factors include the study's significance, scope, limitations, research questions and hypotheses, and the definition of technical terms.
1.2 Background of Study
Cement production remains a cornerstone of global infrastructure development, particularly in rapidly urbanizing and industrializing nations. It serves as the essential binding agent in concrete, which is the most widely used construction material in the world. However, the production process is heavily dependent on traditional raw materials such as limestone, clay, shale, and gypsum. These materials are not only finite but also associated with significant environmental and economic challenges. According to Hewlett and Liska (2019), the depletion of high-quality limestone deposits and the intensive energy consumption in cement manufacturing are driving concerns about the long-term sustainability of the industry.
As cement demand grew during the Industrial Revolution and throughout the 20th century, so did the consumption of natural raw materials. Andrew (2018) reported that the cement industry had become a major contributor to global carbon dioxide emissions, spurring research into less harmful alternatives. During this period, industrial by-products such as fly ash from coal combustion and blast furnace slag from steel production started being explored as potential supplementary cementitious materials.
The oil crises of the 1970s further accelerated interest in energy-saving measures and raw material substitution in cement production. Benhelal et al. (2013) noted that energy efficiency and environmental sustainability became more prominent in the global cement agenda, encouraging innovation in the use of alternative raw materials. In the decades that followed, pozzolanic materials such as volcanic ash, rice husk ash, silica fume, and metakaolin began to receive greater attention due to their availability and chemical compatibility with cement clinker.
The late 20th and early 21st centuries witnessed a surge in international initiatives focused on sustainable construction and green building materials. As a result, various countries developed standards and guidelines to incorporate supplementary cementitious materials into cement and concrete formulations. Obonyo and Chipungu (2018) asserted that in regions like sub-Saharan Africa, there has been increasing recognition of the need to localize raw material sourcing by using agricultural and industrial waste that would otherwise be discarded.
Benhelal et al. (2013) asserted that alternative raw materials such as fly ash, rice husk ash, silica fume, and ground granulated blast furnace slag can partially or fully replace conventional cement ingredients without compromising the quality of the final product. These materials, often derived from industrial or agricultural waste, provide dual benefits: they help in reducing cement's environmental footprint and offer a solution for waste management. Obonyo and Chipungu (2018) contended that the use of locally available waste materials in cement production is a viable strategy for promoting sustainability and reducing import dependency in many developing countries.
On a practical level, the incorporation of alternative raw materials has shown promising results. Camoes et al. (2017) stated that cement blended with supplementary materials such as pozzolans and slags demonstrates comparable or even superior performance in terms of durability and strength. Furthermore, Zhang and Ahmari (2012) affirmed that geopolymer cements made from alternative aluminosilicate sources can drastically lower energy consumption and CO2emissions, marking a significant innovation in green construction. This study is set against the backdrop of identifying and evaluating alternative raw material sources that could revolutionize cement production, reduce environmental harm, and support sustainable development goals.
1.3 Statement of Problems
Investigation revealed that the industry is heavily reliant on traditional raw materials such as limestone, clay, shale, and gypsum, which are becoming increasingly scarce due to continuous extraction and environmental degradation. The overdependence on these conventional sources is posing significant economic and environmental challenges, including rising production costs, land degradation, and depletion of non-renewable resources (Mushonga & Nyanganyura, 2020).
In many regions, particularly in developing countries, the cost of cement production is substantially high due to the need to import some of these raw materials or the energy-intensive processes required to process them. In addition, the traditional method of cement production emits a considerable amount of carbon dioxide, contributing significantly to global climate change (Andrew, 2018).
Furthermore, there are numerous alternative raw materials such as industrial by-products, agricultural waste, and locally available pozzolanic materials that are either underutilized or entirely ignored. However, there is limited awareness, inadequate research, and a lack of policy direction to encourage the adoption of such alternatives in many parts of the world, including Nigeria (Obonyo & Chipungu, 2018). It is against this backdrop that this study seeks to explore and evaluate alternative raw material sources for cement production.
1.4 Aim and Objectives of Study
The aim of the study is to assess the potential of alternative raw materials in cement production and determine their environmental, technical, and economic viability. In achieving this aim, the following specific objectives were laid out as follows:
- To examine the environmental and economic impact of using alternative raw materials in cement production.
- To identify and evaluate various alternative raw materials that can substitute conventional cement inputs.
- To determine the performance and suitability of cement produced using alternative materials.
- To explore the challenges and opportunities associated with the adoption of alternative materials in Nigeria's cement industry.
1.5 Research Questions
The study came up with research questions so as to be able to ascertain the above stated objectives. The specific research questions for the study are stated below as follows:
- What types of alternative raw materials are suitable for use in cement production?
- What are the environmental and economic impacts of using alternative raw materials in cement production?
- How does cement made with alternative materials perform compared to conventional cement?
- What are the major barriers and enablers to adopting alternative raw materials in Nigeria's cement industry?
1.6 Significance of Study
The outcome of this research study will provide a basis for developing policies that support green practices and local resource utilization. In addition, the findings will be beneficial to cement manufacturers by offering cost-effective and locally available alternatives that can lower production expenses while maintaining product quality.
Furthermore, communities and the general public will benefit, as the wider adoption of sustainable practices in the cement industry will contribute to cleaner environments, reduced industrial waste, and improved health outcomes due to lower emissions and less resource exploitation.
Lastly, the study will serve as a reference point for future research, promoting further investigation into local raw material utilization and sustainable construction practices.
1.7 Scope and Limitations of the Study
This study focuses on the evaluation of alternative raw material sources for cement production in Lafarge Cement Company, Ewekoro Plant, Ogun State, Nigeria. It covers the types of materials used, production processes, environmental and economic implications, and the company's efforts in adopting sustainable practices.
However, the study was limited by insufficient access to confidential company data, delays in obtaining responses from technical staff, frequent power outages during fieldwork, financial limitations that restricted broader sampling, and time constraints that affected the extent of material testing.
1.8 Definition of Terms
Cement: A fine powder made from calcined limestone and clay that, when mixed with water, hardens to bind other materials together in construction (Hewlett & Liska, 2019).
Alternative Raw Materials: Non-traditional materials, often derived from industrial or agricultural waste, used to substitute or supplement conventional raw materials in cement production (Benhelal et al., 2013).
Pozzolans: Siliceous or siliceous-aluminous materials that, when finely divided and mixed with lime and water, form compounds with cementitious properties (Obonyo & Chipungu, 2018).
CO2 Emissions: The release of carbon dioxide into the atmosphere from industrial activities, including the combustion and chemical processing involved in cement manufacturing (Andrew, 2018).
…