DEPARTMENT OF STRUCTURAL ENGINEERING

This study aims to optimize reinforced concrete (RC) bridge decks using the Leonhardt and Makowski method. A MATLAB based GUI for live load distribution analysis was developed, allowing users to observe the impact of varying design parameters like span, slab thickness, and deck width. The analysis will follow BS5400 provisions, focusing on HA and HB loading combination. The methodology involved creating a MATLAB program that integrates the Leonhardt method into an interactive GUI and MATLAB scripts to run batch inputs. This tool validates user inputs, apply load cases (UDL, KEL, HB vehicle loads), compute section properties, and generate both tabular and graphical outputs (e.g., bending moment diagrams). To verify accuracy, results from manual calculations for bridge of span 25m, deck width of 11m and slab thickness 230mm was compared. The MATLAB tool is showed strong agreement with both manual calculations with 0.002% difference while the percentage difference compared to the STAAD.Pro analysis was 2.97% when computing the maximum longitudinal bending moments. The parametric study showed that the maximum moments appeared on the first support. The tool created will be able to provide engineers and students a flexible environment to explore design alternatives and understand how the inputs influence bridge behavior. Although the MATLAB GUI developed in this study performed excellently when compared to manual calculation, more comparative testing with other load distribution methods and with finite element based tool to further test the accuracy of the study.

The continuous increase in cement production has raised serious environmental concerns due to its high energy consumption and carbon emissions. At the same time, large quantities of agricultural and wood-processing wastes such as plantain husks and sawdust are generated daily and often disposed of indiscriminately, contributing to environmental pollution. This study investigates the potential use of Plantain Husk Ash (PHA) and Sawdust Ash (SDA) as partial replacements for Ordinary Portland Cement in concrete production as a means of promoting sustainable construction practices. Concrete was produced using a 1:2:4 mix ratio, with cement partially replaced by a blended combination of PHA and SDA in equal proportions at replacement levels of 5%, 10%, 15%, 20%, and 25% by weight of cement. The workability of the fresh concrete was evaluated using the slump test, while compressive and flexural strength tests were carried out after 7, 14, and 28 days of water curing in accordance with relevant British Standards (BS EN) specifications. The experimental results indicated that workability decreased progressively with increasing replacement levels due to the higher water absorption characteristics of the ashes. Similarly, compressive and flexural strengths reduced as the percentage of replacement increased. However, concrete mixes containing up to 10–15% replacement achieved satisfactory strength values suitable for non-structural applications and certain light structural uses. The study concludes that Plantain Husk Ash and Sawdust Ash can be effectively utilized as supplementary cementitious materials in concrete at controlled replacement levels. Their use not only reduces dependence on conventional cement but also provides an environmentally friendly method of managing agro-industrial waste, thereby contributing to sustainable and cost-effective concrete production.

This study investigates the effect of palm oil fuel ash (POFA), an agro-industrial by-product, as an additive partial replacement for cement in stabilizing laterite cubes, with a focus on enhancing compressive strength and reducing water absorption while promoting sustainable construction practices. The aim is to evaluate POFA's potential as a pozzolanic additive to mitigate the environmental and economic drawbacks of traditional cement use in lateritic soil stabilization, particularly in tropical regions like Nigeria where laterite and POFA are abundant. The specific objectives include: characterizing the physical and chemical properties of laterite soil, ordinary Portland cement (OPC), and treated POFA; assessing the compressive strength of stabilized laterite cubes at curing ages of 7, 14, and 28 days for POFA replacement levels of 0%, 10%, and 20% by weight of cement; evaluating water absorption characteristics at 28 days across these replacement levels; determining the optimal POFA dosage for the best balance of strength and durability; and comparing the results against civil engineering standards to validate practical applicability. Methodologically, laterite soil was sourced from Benin City, Nigeria, air-dried, and sieved through a 4.75 mm mesh to remove contaminants. POFA was obtained from a local palm oil mill, sun-dried, and finely ground to pass a 75 μm sieve, ensuring high pozzolanic activity due to its silica content (58.4% SiO₂). OPC conforming to ASTM C150 was used as the primary binder. Mix designs followed an additive approach, with laterite as the base (100%) and cement/POFA added in proportionsof 0, 10 and 20%. A water-binder ratio of 0.55 was maintained, and a total of 63 cubes (100 mm × 100 mm × 100 mm) were cast. Specimens were demolded after 24 hours and cured via full water immersion at 27 ± 2°C for the specified periods. Testing involved compressive strength and water absorption calculated as the percentage weight gain after 24-hour immersion. Material characterization included specific gravity (laterite: 2.65, cement: 3.15, POFA: 2.42), fineness, particle size, and oxide composition via X-ray fluorescence. Results indicate that POFA significantly influences both physical and mechanical properties. Chemically, POFA qualifies as a Class F pozzolan per ASTM C618. Dry density andWater absorption were done which gave its higher value at 10%. Compressive strength development showed marked improvements with POFA incorporation. The unstabilized control (100% laterite) yielded only 1.74 N/mm² at 28 days, unsuitable for structural use. Cement alone boosted strength to 3.93 N/mm² (10% cement) and 5.40 N/mm² (20% cement). The synergistic effect was most evident in mixes with both cement and POFA due to pozzolanic enhancement, filler effects, and accelerated hydration. Strength gains were delayed but sustained in POFA mixes, with 7day strengths lower but surpassing controls by 28 days. Overall, 10% POFA replacement optimized performance, meeting requirements for non-load-bearing applications. In conclusion, POFA at 10% replacement level is an effective, sustainable additive for laterite stabilization, reducing cement consumption by up to 50%, repurposing waste to lower environmental pollution and embodied CO₂, and cutting costs without compromising durability. This supports circular economy principles and SDGs 11 and 12. Recommendations include further field trials for long-term durability, exploration of higher POFA fineness or activation methods to extend optimal replacement beyond 10%, and policy incentives for POFA adoption in low-cost housing. Future studies could incorporate additional admixtures or assess resistance to environmental factors like acid attack or freezethaw cycles to broaden applications in diverse climateThis study investigates the effect of palm oil fuel ash (POFA), an agro-industrial by-product, as an additive partial replacement for cement in stabilizing laterite cubes, with a focus on enhancing compressive strength and reducing water absorption while promoting sustainable construction practices. The aim is to evaluate POFA's potential as a pozzolanic additive to mitigate the environmental and economic drawbacks of traditional cement use in lateritic soil stabilization, particularly in tropical regions like Nigeria where laterite and POFA are abundant. The specific objectives include: characterizing the physical and chemical properties of laterite soil, ordinary Portland cement (OPC), and treated POFA; assessing the compressive strength of stabilized laterite cubes at curing ages of 7, 14, and 28 days for POFA replacement levels of 0%, 10%, and 20% by weight of cement; evaluating water absorption characteristics at 28 days across these replacement levels; determining the optimal POFA dosage for the best balance of strength and durability; and comparing the results against civil engineering standards to validate practical applicability. Methodologically, laterite soil was sourced from Benin City, Nigeria, air-dried, and sieved through a 4.75 mm mesh to remove contaminants. POFA was obtained from a local palm oil mill, sun-dried, and finely ground to pass a 75 μm sieve, ensuring high pozzolanic activity due to its silica content (58.4% SiO₂). OPC conforming to ASTM C150 was used as the primary binder. Mix designs followed an additive approach, with laterite as the base (100%) and cement/POFA added in proportionsof 0, 10 and 20%. A water-binder ratio of 0.55 was maintained, and a total of 63 cubes (100 mm × 100 mm × 100 mm) were cast. Specimens were demolded after 24 hours and cured via full water immersion at 27 ± 2°C for the specified periods. Testing involved compressive strength and water absorption calculated as the percentage weight gain after 24-hour immersion. Material characterization included specific gravity (laterite: 2.65, cement: 3.15, POFA: 2.42), fineness, particle size, and oxide composition via X-ray fluorescence. Results indicate that POFA significantly influences both physical and mechanical properties. Chemically, POFA qualifies as a Class F pozzolan per ASTM C618. Dry density andWater absorption were done which gave its higher value at 10%. Compressive strength development showed marked improvements with POFA incorporation. The unstabilized control (100% laterite) yielded only 1.74 N/mm² at 28 days, unsuitable for structural use. Cement alone boosted strength to 3.93 N/mm² (10% cement) and 5.40 N/mm² (20% cement). The synergistic effect was most evident in mixes with both cement and POFA due to pozzolanic enhancement, filler effects, and accelerated hydration. Strength gains were delayed but sustained in POFA mixes, with 7day strengths lower but surpassing controls by 28 days. Overall, 10% POFA replacement optimized performance, meeting requirements for non-load-bearing applications. In conclusion, POFA at 10% replacement level is an effective, sustainable additive for laterite stabilization, reducing cement consumption by up to 50%, repurposing waste to lower environmental pollution and embodied CO₂, and cutting costs without compromising durability. This supports circular economy principles and SDGs 11 and 12. Recommendations include further field trials for long-term durability, exploration of higher POFA fineness or activation methods to extend optimal replacement beyond 10%, and policy incentives for POFA adoption in low-cost housing. Future studies could incorporate additional admixtures or assess resistance to environmental factors like acid attack or freezethaw cycles to broaden applications in diverse climate

As sustainability becomes an essential focus in modern construction, the exploration of alternative materials and the reuse of industrial waste have gained increasing attention. This study examines the feasibility of using wood ash (WA) as a partial replacement for Ordinary Portland Cement (OPC) in the production of Grade 25 concrete, assessing its effects on workability and compressive strength. Concrete samples were produced using a 1:1:2 mix ratio with a 0.41 water–cement ratio, incorporating 0%, 5%, 10%, 15%, and 20% replacements of cement by wood ash. Tests conducted included particle size distribution, slump test, compressive strength test, and water absorption test, with evaluations carried out at 7, 14, and 28 days of curing. The results revealed a consistent reduction in workability as wood ash content increased, with slump values decreasing from 30 mm (control) to 0 mm at 20% replacement. Compressive strength results showed that 5% replacement yielded comparable performance to the control mix (32.49 N/mm² vs. 32.51 N/mm²), while higher replacement levels resulted in strength reduction. Water absorption tests indicated varied permeability levels. The 5% replacement demonstrated an absorption rate of 6.21%, conforming to BS 1881 122:2011, while 10%, 15%, and 20% replacements recorded progressively lower values, with 20% achieving 1.25%, indicating excellent quality and durability. Based on these findings, the study concludes that wood ash can effectively replace up to 5% of cement in structural concrete applications without significant compromise in strength or durability. Beyond this level, the decrease in strength suggests that higher replacements are more suitable for non-structural uses, such as blocks or pavements, where lower strength requirements apply

The increasing demand for sustainable and environmentally friendly construction materials has prompted the exploration of alternative waste materials for use in concrete production. This study investigates the partial replacement of fine aggregate with periwinkle shell in concrete as a means of reducing construction costs, conserving natural resources, and promoting waste utilization. The research evaluates the effects of incorporating varying percentages of processed periwinkle shell as a substitute for fine aggregate on the properties of concrete.
Concrete mixes were prepared with different replacement levels of fine aggregate using periwinkle shell, while a control mix containing conventional materials was also produced. Standard laboratory tests were conducted to determine the workability, density, compressive strength, and durability characteristics of the concrete specimens. The results indicate that the inclusion of periwinkle shell influences the fresh and hardened properties of concrete. Workability generally decreased with increasing replacement levels, while compressive strength showed acceptable performance at lower replacement percentages. The density of the concrete also reduced, suggesting the potential for producing lightweight concrete.
The findings reveal that periwinkle shell can be effectively utilized as a partial replacement for fine aggregate in concrete production without significantly compromising structural performance when used within optimal replacement limits. The study concludes that the use of periwinkle shell contributes to sustainable construction practices by reducing environmental waste and the dependence on natural sand resources. It is recommended that partial replacement levels within the optimum range be adopted for non-critical and selected structural applications

This project focused on the structural design of a 100 m³ elevated reinforced concrete (RC) water tank supported by a 20-meter-high tower. The objective was to ensure the structural safety, stability, and serviceability of all components including the raft foundation, tank base slab, beams, columns, and tank walls under combined actions of dead load, live load, hydrostatic pressure, wind, and seismic forces in compliance with BS 8110 and Eurocode 2 standards. The methodology involved manual structural design calculations for preliminary sizing and load estimation, followed by detailed structural analysis and modelling using ProtaStructure software. The structure consists of 300 mm × 300 mm reinforced concrete columns, 300 mm × 450 mm reinforced concrete beams, a 150 mm reinforced concrete raft foundation at ground level, and a 300 mm reinforced concrete tank base slab positioned at the top of the stanchions to safely support the water tank. The tank walls, which serve as the primary water-retaining elements, were designed as 250 mm thick reinforced concrete walls reinforced with high-yield steel bars (Grade 500) using 12 mm diameter bars spaced at 250 mm centres in both vertical and horizontal directions (H12-250) on both faces of the wall. The tank base slab was reinforced in orthogonal directions to resist bending moments and shear forces caused by hydrostatic pressure, self-weight, and wind effects. Beams supporting the platform and tank were subjected to maximum moments of 230.6 kN·m and axial loads of 191.1 kN, and were reinforced using T20 and T25 longitudinal bars together with T10 shear links. Columns carried maximum axial loads of 1443.6 kN and were reinforced with up to 4Y25 bars. The structural analysis revealed that the maximum lateral displacement of the structure was 9.87 mm at the top storey, which is within the allowable serviceability limit of H/500 according to Eurocode EN 1991-1-4 for a 20 m high structure. The slab deflections, beam moments, shear forces, and column forces were all within codespecified limits, indicating an efficient and stable structural system. The Bill of Engineering Measurement and Evaluation (BEME) estimated the total construction cost of the proposed elevated water tank and tower structure at approximately ₦19,114,573. The project concludes that the elevated reinforced concrete water tank and supporting tower satisfy all structural and serviceability requirements and that the integration of manual calculations with software analysis produced a safe, durable, and economical water storage structure suitable for practical implementation.