ABSTRACT: The construction industry constantly seeks innovative solutions to enhance the performance and durability of building materials. In recent years, nanotechnology has emerged as a promising avenue for improving the properties of cement-based materials, such as mortar (Mehta & Monteiro, 2016). The incorporation of Nano-sized Supplementary Cementitious Materials (SCMs) into mortar mixes has shown significant potential to enhance mechanical properties, particularly compressive strength. SCMs, such as silica fume, fly ash, and ground granulated blast furnace slag, have been traditionally used to improve the workability, durability, and environmental sustainability of concrete. However, their effectiveness can be further enhanced by reducing their particle size to the Nano scale (1-100 nanometers) (Siddique & Lee, 2018). Nano-sized SCMs, such as Nano-silica and Nano-clay, exhibit unique properties due to their high surface area and reactivity. These properties can lead to improved pore structure, enhanced hydration reactions, and a denser microstructure within the mortar matrix (Siddique & Lee, 2018). This in turn can significantly enhance the compressive strength of mortar, leading to more robust and durable structures. The incorporation of these materials can also mitigate issues such as shrinkage and cracking, which are common in traditional mortar mixes (Siddique & Klaus, 2017). TABLE OF CONTENT........................................................................1 CHAPTER ONE.................................................................................2 INTRODUCTION...............................................................................2 1.1 BACKGROUND OF STUDY...........................................................2 1.2 AIM.............................................................................................3 1.3 OBJECTIVES.................................................................................3 1.4 STATEMENT OF PROBLEM...........................................................4 1.5 SIGNIFICANCE OF THE STUDY.........................................................5 CHAPTER TWO........................................................................................6 LITERATURE REVIEW...............................................................................6 2.1 Overview of Nano-Sized Supplementary Cementitious Materials (SCMs)....................................................................................................6 2.2 Strength Properties of Mortar Modified with SCMs...........................8 2.3 Optimization of Mix Ratios Using Taguchi Method.............................8 2.4 Analysis of Variance (ANOVA) in Parameter Significance....................9 2.5 Confirmatory Experiments and Validation..........................................9 2.6 Microstructural and Mechanical Benefits............................................10 2.7 Economic Viability................................................................................10 CHAPTER ONE: INTRODUCTION 1.1 BACKGROUND OF STUDY Mortar strength is a critical factor in the overall performance of masonry structures. The compressive strength of mortar not only affects the load-bearing capacity but also influences durability and resistance to environmental factors. The incorporation of Nano-sized SCMs has been shown to significantly enhance these properties. For example, a study by Sadeghi et al. (2020) demonstrated that the addition of Nano-silica and Nano-clay improved the compressive strength and flexural strength of mortar, leading to a more resilient material capable of withstanding various stresses. Furthermore, the microstructural benefits provided by Nano-sized materials contribute to improved adhesion between mortar and masonry units, which is essential for structural integrity (Hosseini et al. 2019). The enhanced bonding characteristics can lead to reduced failure rates in masonry applications, making Nano-modified mortar a viable option for modern construction. 1.2 AIM To evaluate the strength of mortar modified with effect of Nano-sized Supplementary Cementitious Materials (SCMs) (rice husk and palm oil fuel ash) on the strength of concrete. This research investigates the influence of various Nano-sized SCMs on the compressive strength of mortar. By systematically varying the type and dosage of Nano-sized SCMs, this study will provide valuable insights into their optimal utilization for achieving superior mortar performance. The findings of this research have the potential to contribute to the development of more sustainable and high-performance construction materials, addressing the ever-growing demand for improved infrastructure and building technologies. 1.3 OBJECTIVES 1. Characterize the materials to be used in the study 2. Determine the strength properties of mortar using various mix ratios obtained from Taguchi designed experiment 3. Utilize Taguchi designed experiment for the optimization of the strength properties 4. Analyze the significance of the parameters using analysis of variance (ANOVA) 5. Integrate Taguchi method with other numerical or analytical approach to optimize the additives concurrently 6. Conduct confirmatory test on the optimal mix ratio from the Taguchi designed experiment. 7. Perform microstructural analysis on the optimal mix ratio for modified samples subjected to 3, 7, 14, 21 and 28 days of curing. 1.4 STATEMENT OF PROBLEM The construction industry in Nigeria faces several significant challenges that hinder its growth and sustainability. In particular, the rising cost of cement, the instability associated with its production and performance, and the environmental impact of traditional cement manufacturing processes are pressing issues. The challenges posed by the rising cost of cement, the instability of its performance, and the environmental harm associated with its production are significant issues for the construction industry in Nigeria, particularly in Nsukka, Enugu State. This study aims to investigate how the incorporation of Nano-sized supplementary cementitious materials can address these problems, leading to enhanced mortar strength and promoting sustainable construction practices in the region. 1.4.1 Cost of Cement In Nigeria, the cost of cement has been a major concern for builders and developers. The price of cement has seen substantial increases due to factors such as inflation, high transportation costs, and fluctuating energy prices (NBS, 2022). For instance, the price of a 50 kg bag of cement has risen significantly, making it one of the highest costs in construction projects. In Nsukka, where many construction projects are ongoing, these rising costs can lead to budget overruns and delays. The integration of Nano-sized SCMs into mortar formulations presents a potential solution to reduce the dependency on conventional cement, thereby lowering overall material costs and making construction more affordable for local builders. 1.4.2 Instability of Cement The instability of cement performance is another critical issue in Nigeria's construction sector. Variability in the quality of locally sourced raw materials, in consistent manufacturing processes, and environmental conditions can lead to significant fluctuations in the strength and durability of cement-based materials (Ogunbiyi et al 2021). In Nsukka, builders often face challenges related to the quality of cement, which can result in structural failures and increased maintenance costs. The addition of Nano-sized SCMs can enhance the microstructure of mortar, improving its strength and consistency. This can lead to more reliable performance in construction, reducing the risks associated with unstable cement quality. 1.4.3 Harmfulness to the Environment. The environmental impact of cement production is a global concern, and Nigeria is no exception. The cement industry is responsible for a significant portion of greenhouse gas emissions, contributing to climate change and environmental degradation (Adelekan et al 2020). 1.5 SIGNIFICANCE OF THE STUDY 1.5.1 Save Cost Incorporating Nano-sized SCMs into mortar formulations can lead to substantial cost savings for construction projects in Nsukka. The rising costs of cement, driven by factors such as inflation, transportation, and energy prices, significantly impact the overall budget of construction activities. By partially replacing conventional cement with Nano-sized SCMs, builders can: Reduce Material Costs: Lowering the amount of cement used in mixes decreases the overall material expenses, making construction more affordable. Minimize Transportation Costs: SCMs can often be sourced locally from industrial by-products, reducing the need for long-distance transport and associated costs. Lower Maintenance Expenses: Enhanced durability and performance characteristics of Nano modified mortars can lead to fewer repairs and maintenance overtime, resulting in long term financial benefits. 1.5.2 Save Environment The environmental significance of utilizing Nano-sized SCMs in cementitious materials is profound. Traditional cement production is a major source of greenhouse gas emissions, contributing to climate change and environmental degradation. By adopting Nano-sized SCMs, the construction industry can reduce Carbon Footprint: Partial replacement of conventional cement with SCMs can significantly lower CO2 emissions associated with cement production, contributing to global efforts to combat climate change. CHAPTER TWO LITERATURE REVIEW 2.1 Overview of Nano-Sized Supplementary Cementitious Materials (SCMs): Nano-sized supplementary cementitious materials (SCMs) have emerged as sustainable alternatives in cementitious systems, offering numerous benefits such as reduced carbon footprint, enhanced mechanical properties, and improved durability. SCMs like rice husk ash (RHA) and palm oil fuel ash (POFA) are derived from agricultural by-products, making their use not only environmentally friendly but also economically viable. 2.1.1 Rice Husk Ash (RHA): Rice husk a by-product of rice milling, contains approximately 85–90% silica after incineration under controlled conditions. At the Nano scale, the silica in RHA transforms into highly reactive amorphous silica. The amorphous structure enables effective pozzolanic activity, leading to the formation of secondary calcium silicate hydrate (C-S-H) gel during hydration reactions (Mehta & Monteiro, 2014). Studies by Ganesan et al. (2013) revealed that RHA enhances compressive strength and reduces permeability due to its fine particle size and high reactivity. Derived from the combustion of rice husks, RHA contains up to 90% amorphous silica, making it a potent SCM (Rasoul et al. 2017). Reactivity: The high surface area and amorphous nature of RHA enhance its pozzolanic activity, leading to improved long-term strength in mortar (Mehta & Monteiro 2016 PROCESSING OF RICE HUSK ASH: Achieving Nano scale dimensions involves grinding and sieving the ash to improve its surface area and reactivity. Research emphasizes the role of controlled incineration to minimize unburnt carbon and ensure optimal silica content. 2.1.2 Palm Oil Fuel Ash (POFA): POFA is a by-product of palm oil production, composed mainly of silica, alumina, and trace amounts of lime and magnesia. The pozzolanic behavior of POFA is attributed to its high silica content, which reacts with calcium hydroxide to form additional C-S-H gel. Studies by Awal and Hussin (2017) demonstrated that POFA-modified concrete exhibits superior durability properties, including resistance to chloride penetration and sulfate attack. POFA is an agricultural by-product generated from the incineration of palm oil residues. Proper processing, including grinding to achieve ultra-fine particles, significantly enhances its reactivity (Amran et al., 2021). CHEMICAL CHARACTERISTICS: POFA is rich in silica and alumina, which contribute to its pozzolanic behavior and ability to improve mortar durability (Yusof et al. 2015). Processing of POFA: Similar to RHA, POFA requires grinding and sieving to achieve a fine particle size. The calcination process plays a significant role in determining its reactivity. 2.1.3 Benefits of Nano-Sized SCMs: Nano-sized SCMs contribute to: 1 Improved particle packing density, reducing porosity and enhancing strength. 2. Faster pozzolanic reactions due to increased surface area. 3. Enhanced interfacial transition zones (ITZ) in cementitious systems, leading to better load transfer. 2.2. Strength Properties of Mortar Modified with SCMs: Properties of mortar and concrete. The key strength properties affected include compressive strength, flexural strength, tensile strength, and durability. 2.2.1. Impacts on Flexural Strength: Flexural strength improvements have been linked to better ITZs and reduced porosity. Research by Chindaprasirt et al. (2012) revealed that the use of Nano-sized RHA and POFA enhances the bonding between aggregate and paste, leading to higher flexural strength. Nano-SCMs contribute to improved bonding between mortar and masonry units, enhancing flexural strength and overall structural integrity (Hosseini et al. 2019) 2.3 Optimization of Mix Ratios Using Taguchi Method: The Taguchi method, a robust statistical optimization technique, is extensively used in materials research to design experiments that identify optimal process parameters. The method focuses on achieving high-quality results with minimal experimental trials, making it cost-effective and efficient (Taguchi, 1986). Optimization Techniques for Nano-SCMs: 2.3.1. Taguchi Method The Taguchi method systematically optimizes mix designs by minimizing experimental trials and identifying optimal combinations of variables. Vasanthi and Selvan (2020) optimized Nano silica content using this method, achieving superior compressive strength and reduced water absorption. Ikeagwuani et al. (2020) combined the Taguchi method with fuzzy logic to optimize ternary additives, demonstrating its versatility in complex systems. POFA and RHA Blends: The combination of POFA and RHA has been optimized to achieve synergistic effects, enhancing both strength and durability (Amran et al. 2021). 2.3.2. Application of Taguchi method in Mortar Research: Studies using the Taguchi method for SCM optimization have demonstrated its effectiveness in identifying the best mix ratios for maximizing compressive and flexural strength while minimizing water absorption (Roy, 2001). 2.4 Analysis of Variance (ANOVA) in Parameter Significance: ANOVA is a statistical tool used to analyze the impact of individual factors and their interactions on experimental outcomes. In mortar research, ANOVA helps quantify the significance of parameters such as W/C ratio, SCM content, and curing time on strength properties. ANOVA has been used to determine the significance of parameters such as Nano-SCM dosage and curing time, providing insights into their impact on mortar properties (González et al. 2022). Key Findings from ANOVA Studies: ▪ The W/C ratio often emerges as the most significant factor influencing compressive strength (Montgomery, 2017). ▪ Interactions between SCMs and other parameters (e.g. curing time) are critical in determining overall performance (Fisher, 1925). 2.4.1. Integration with Taguchi Method: Combining ANOVA with the Taguchi method enables researchers to validate the robustness of optimal mix ratios and ensure their reproducibility. 2.5 Confirmatory Experiments and Validation: Confirmatory experiments validate the results obtained from optimization studies. They involve testing samples with the optimal mix ratio under varying conditions to ensure consistency. Research by Kumar et al. (2020) emphasized the importance of curing time in achieving optimal strength gains, with significant improvements observed at 28 days. 2.6 Microstructural and Mechanical Benefits: Nano-silica accelerates hydration by acting as nucleation sites for calcium silicate hydrate (CSH) formation. This process densifies the microstructure, reducing void spaces, improving compressive strength, and enhancing durability. Vasanthi and Selvan (2020) reported that incorporating 2wt% Nano-silica in mortar increased compressive strength to 51.45 MPa and reduced water absorption to 2.95%. Ltifi et al. (2011) highlighted the significant early-age strength gains facilitated by Nano-silica due to enhanced hydration kinetics. 2.7 Economic Viability: Although Nano-SCMs have higher initial costs, their long-term benefits include enhanced durability, reduced maintenance, and lower lifecycle costs (Amran et al. 2021). For developing regions, locally sourced materials like RHA and POFA provide cost-effective alternatives to traditional cement, as they utilize agricultural and industrial by-products that reduce dependency on conventional cement while mitigating waste management issues ABOUT THE AUTHOR: By name, Igbonwelundu Ebubechukwu Emmanuel is a graduate of the prestigious University of Nigeria in Enugu state where he ascertained his Bachelor’s degree in Civil Engineering. Moving forward he has been able to scout out for supplementary materials that can be used as a substitute for cement during construction work. Hence with the designs rendered with these materials it can be analyzed that these materials are good alternatives to reduce the cost of cement usage on site. These materials are Rice Husk Ash (RHA) and Palm Oil Fuel Ash (POFA), however these materials are to be used in the establishment of structures with a low bearing capacity such as bungalows, duplexes and two-storey buildings because of its light weight in the form of ash. Now this is a proven alternative in reducing the cost of cement supplied to any site in Nigeria as a whole. NAME: IGBONWELUNDU EBUBECHUKWU EMMANUEL INSTITUTION: UNIVERSITY OF NIGERIA NSUKKA, ENUGU STATE PHONE: 08163240788 GMAIL: [email protected]