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Volume 14 (3S); 15 Sep, 2024 [Booklet] [ICCESR-2024]

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Research Paper

Mapping Buildings from Semi-Informal Settlements Using Non-Parametric Classifiers: A Case of Old Naledi

Mpoeleng W, Segobye M, Ouma Y, Moreri K, Manisa BM, Nkwae B, Maphale L and Nkhwanana N.

J. Civil Eng. Urban., 14(3s): 149-157, 2024; pii:S225204302400014-14

DOI: https://dx.doi.org/10.54203/jceu.2024.14

Abstract
Building footprints are essential for planning and designing new infrastructure like water reticulation, electricity transmission, sewer, and road networks. They are also necessary for delivery, census, and disaster management. It is therefore important to have up-to-date maps and GIS databases for service provision. However, mapping building of footprints in semi-informal settlements is problematic because of the spatial heterogeneity of settlements. This study evaluates three non-parametric machine learning algorithms for extracting building footprints from WorldView-2 (WV2) satellite imagery in a semi-informal settlement. WV2 satellite imagery data was fused with gray-level co-occurrence matrices (GLCM) to enhance building extraction. The algorithms used include the Gaussian Mixture Model (GMM), Random Forest (RF), and Support Vector Machine (SVM). The results indicate that GLCM does not improve the detection of buildings when using the GMM algorithm, but it increases building detection with RF and SVM. The GMM algorithm achieved the highest average accuracy of 92% for building detection. However, SVM and RF have an overall accuracy of 79% and 70% respectively. Though RF did not perform very well in identifying individual buildings, its overall accuracy was high. The outcome indicates that machine learning algorithms can adequately map building footprints from high-resolution satellite imagery.
Keywords: Building detection, WorldView-2, machine learning, Gray-Level Co-Occurrence Matrix (GLCM)

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Research Paper

Moment Gradient Factor Verification for Selected Monosymmetric Beams under Linear Moment Gradients

Mudenda K.

J. Civil Eng. Urban., 14(3s): 164-171, 2024; pii:S225204302400016-14

DOI: https://dx.doi.org/10.54203/jceu.2024.16

Abstract
The reuse of doubly symmetric beams by converting them into monosymmetric section beams offers some promising outcomes and has potential for mitigating carbon footprint of structures. However, due to their complexity monosymmetric sections must be used in a configuration that allows the monosymmetry effects to act beneficially. Although the South African design standard for hot-rolled steel does not provide any guidance on the design of monosymmetric beams, the Southern African steel construction handbook provides a formula for determining the critical elastic buckling moment for monosymmetric beams. This guidance implies that the moment gradient factor used for doubly symmetric sections can be used on monosymmetric sections as well. The aim of the study was to verify the validity of this approach of extending the moment gradient factor used for doubly symmetric beams to monosymmetric beams for two specific types of monosymmetric sections. It was found that although this approach appears to be justified for monosymmetric members in single curvature bending it may produce unconservative values of the critical buckling load in double curvature bending between restraint points. The level of un-conservatism also varies for different spans of the same member. This makes it difficult to specify a single moment modification factor value for these cases. The sensitivity in terms of load reduction observed for double curvature bending case was different for the two members examined with this attributed to differences in how the shear centre moves relative to the centroid. It is recommended that the critical buckling load for monosymmetric sections be determined on a case specific basis for members in double curvature from linear moment gradients. Under single curvature bending the moment gradient factor for doubly symmetric members appears to give acceptable predictions of the critical load.
Keywords: Steel beam, Monosymmetric, Lateral-torsional buckling, Moment gradient factor 

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Research Paper

Experiences Encountered while Using Construction Contracts during Project Delivery in Botswana

Ssegawa JK, Ntshwene K, and Kamaruddeen AM.

J. Civil Eng. Urban., 14(3s): 172-181, 2024; pii:S225204302400017-14

DOI: https://dx.doi.org/10.54203/jceu.2024.17

Abstract
Various forms of contracts guide the construction project delivery processes across the world. To make procurement more accessible and faster, various institutions have developed what is known as standard forms of contracts (SFoC). These institutions believe that SFoCs could be used in an adopted or adapted mode to reduce the burden of writing contracts every time a project is procured. This article discusses the results of a study that investigated the effectiveness of identified SFoCs and the experiences encountered by key stakeholders in using the contracts during construction project delivery. Study participants were drawn from contractor, consulting and client organisations and completed a questionnaire with both closed and open-ended questions. 11 attributes synthesised from literature were used to measure the effectiveness of a contract. Three major SFoCs were identified as being used in Botswana: the  Joint Contract Tribunal (JCT),  the New Engineering Contract (NEC) and International Federation of Consulting Engineers  (FIDIC). The FIDIC has a long history of use, but in recent years, the NEC entered the arena. Due to the low usage of the JCT, the discussion centred on the NEC and FIDIC contracts. Some insights were drawn from the study. Respondents did not find a big difference in the effectiveness of the two contracts (WME for NEC =3.3 and FIDIC =3.1). However, there were a few attributes for which the NEC seemed to be a better contract. These were a) simple and non-legalistic language with self-contained clauses and b) a communicative and proactive risk management regime, which respondents identified with a propensity to reduce or avoid disputes. The study had the limitations of having used a small (38) sample of respondents and the fact that NEC has not been used in the country for the length of time as the FIDIC contract.
Keywords: Construction contract, Standard forms of contract, Contract Administration, Construction industry, Botswana 

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Research Paper

Designing Ergonomic Safety Boots for Sustainable Construction in Botswana: A Case Study of Worker Foot Health
Botshabelo K, Sealetsa O, Setlhatlhanyo K. Moalosi R, Rapitsenyane Y, and Dichabeng P.

J. Civil Eng. Urban., 14(3s): 191-198, 2024; pii:S225204302400019-14

DOI: https://dx.doi.org/10.54203/jceu.2024.19

Abstract
The most essential asset in every construction work is the workers. In this regard, sustainability in construction must include and be centred on this vital resource. However, research indicates that civil engineers and construction workers often advocate for sustainability in infrastructural developments. This critical asset in construction often needs more consideration when people are engaged in construction work despite the many ergonomics challenges widely reported in the industry. This leads to workers in this industry being grossly afflicted by injuries such as musculoskeletal disorders, particularly of the foot. In addition, changes in global temperatures, attributed to global warming, situate civil engineers and construction workers, as they often work in open and challenging terrains, at risk of heat-related illnesses such as heat hyperpyrexia and heat exhaustion, which may also aggravate these musculoskeletal disorders conditions. However, it is pretty disturbing to notice that such illnesses are less investigated, particularly musculoskeletal disorders of the feet, which may be exasperated by the dire heat conditions noticeable in Botswana. This is because there is often a need for more knowledge and understanding of the risks associated with musculoskeletal disorders (MSDs). Furthermore, expertise in ergonomics is limited to assisting in the design of work as well as its conditions. This bequeaths both civil engineers and construction workers to operate under very challenging conditions despite pursuance of sustainability. Therefore, this case study investigated the prevalence of musculoskeletal disorders of the feet in the construction industry in Botswana with the purpose of designing a safety boot that matches the anthropometric measurements of the construction workers' feet. The research culminates in the design of a safety boot that is based on the workers' anthropometric measurements to prevent the occurrence of MSDs. The results of the study indicate that workers in this industry suffer from toe bunions, cons, toe deformities, smelly feet, etc. The study additionally indicates foot size differences across Botswana’s tribes. These differences may have severe implications for the use of safety boots and the development of ergonomics illnesses, mainly since the current safety boots used are imported from elsewhere with no modification to address the anthropometric feet measurements of Batswana. It is anticipated that the research will provide the necessary awareness that can help civil engineers explore sustainability not only from the context of infrastructural development (objects) but also from the perspective of workers (humans). This underscores the need for further research and action in this critical area.
Keywords: Construction Worker Ergonomics, Musculoskeletal Disorders, Safety Boot Design, Anthropometric Measurements, Heat-related Illnesses, Sustainable Construction Practices

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Research Paper

Effects of Resampled DEM on Watershed Characteristics and Prediction of Sediment Load in Oyun Watershed, Kwara, Nigeria

Adeogun AG, Mansur AW and Mohammed AA.

J. Civil Eng. Urban., 14(3s): 199-205, 2024; pii:S225204302400020-14

DOI: https://dx.doi.org/10.54203/jceu.2024.20

Abstract
Understanding the terrain and its impact on watershed characteristics, streamflow, and sediment loading is crucial for effective water resource management. This study investigates the influence of resampled Digital Elevation Models (DEM) on the prediction of watershed characteristics, streamflow, and sediment loading upstream of Oyun River Watershed, Nigeria. Various DEM resolutions, ranging from 30-meter to 90-meter, were analysed to assess their effects on hydrological predictions. To delineate the watershed, a DEM of 90-meter resolution was sourced from the space Shuttle Radar Topography Mission (SRTM), and the ASTER global DEM data sources. The 90-meter resolution was resampled to four different resolutions which are 75-meter, 60-meter, 45-meter, and 30-meter resolutions. The watershed and streamline were delineated, and the hydrologic simulation was performed using Soil and Water Assessment Tool (SWAT). The research findings revealed that changes in DEM resolution had a negligible impact on streamflow predictions within the Oyun River Watershed. However, a noticeable impact was observed in the prediction of sediment concentration. The 90-meter resolution DEM yielded the lowest predicted sediment concentration, measuring 2.28 mg/l, while the 30-meter resampled DEM produced the highest value at 5.21mg/l. Similarly, the sediment yield (SYLD t/ha) exhibited considerable variation across the different DEM resolutions, with the 90-meter DEM demonstrating the lowest value of approximately 528.90 t/ha, and the 30-meter DEM registering the highest at 2145.57 t/ha. Overall, this research highlights the necessity of careful DEM selection in hydrological modelling to ensure a comprehensive understanding of watershed dynamics, particularly in regions where sediment transport and water quality are of paramount concern.
Keywords: DEM, Hydrological Modelling, Nigeria, Sediment Loads, Watershed

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Research Paper

Stakeholders Influence on Construction Project Success

Mwakamui HK, Ntshwene K.

J. Civil Eng. Urban., 14(3s): 206-211, 2024; pii:S225204302400021-14

DOI: https://dx.doi.org/10.54203/jceu.2024.21

Abstract
For the past decade Botswana’s construction industry has been embroiled in a lot of controversies based on construction project constraints. These are characterized by construction project delays, budget overruns as well as scope creep and some of these construction projects have been deemed unsuccessful by different stakeholders. To find a mitigating factor for these problems, construction project constraints must be investigated beyond just the triple constraints to provide a solution for the Botswana construction industry. Therefore, the overall purpose of this study was to investigate how construction project constraints and stakeholders influence the outcome of a project. The study adopted a qualitative approach through face-to-face interviews with selected stakeholders such construction professionals, clients and other beneficiaries in the Gaborone and greater Gaborone areas. Thematic analysis was used to analyze data. The findings of the study established that the success of a construction project is subjective and is based on who is being asked, the construction professionals, the client and other beneficiaries had different perspectives on success of a project. The study revealed that initial constraints in a construction project tend to be carried along to the final stages of a construction project. However new few construction project constraints also emerge at the final stages of a construction project. The study found that stakeholders such as the client and other beneficiaries have a significant impact on construction projects due to their influence both positive and negative depending on the level of engagement.
Keywords: Factors of project success, Project constraints, Stakeholders, Triple constraints

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Review

Navigating Climate Change: A Review of Policies in Botswana, Africa, and Beyond

Makoba M, Chaba TL, and Ramontsho QJ.

J. Civil Eng. Urban., 14(3s): 220-228, 2024; pii:S225204302400023-14

DOI: https://dx.doi.org/10.54203/jceu.2024.23

Abstract
This paper is an insightful perspective analysis of Botswana climate change policies in an effort to establish their effectiveness in relation to regional and international initiatives. For a critical review of both mitigation and adaptation efforts by different countries, the effectiveness is analysed, including their strengths and inadequacies noted, and recommendations made towards enhancing policy coherence and effectiveness. It examines the steps Botswana and other countries have taken to cut greenhouse gas emissions, improve energy efficiency, support the use of renewable energy sources, and implement sustainable land management practices. The paper also delves into Botswana's efforts to build climate resilience, such as creating a National Adaptation Plan and incorporating climate considerations across various sectors.
Keywords: Climate change policies, Policy review, International agreements, Sustainable development, Botswana

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Research Paper

Flexible Vegetation Behavior under Varying Areal Densities and Effects on Flow Structures: Numerical Observations

Busari AO and John KA.

J. Civil Eng. Urban., 14(3s): 229-237, 2024; pii:S225204302400024-14

DOI: https://dx.doi.org/10.54203/jceu.2024.24

Abstract
This study carried out extensive numerical studies on a refined “One dimensional (1-D) Reynolds Averaging Navier-Stokes (RANS) Model” for vegetated open channel flow.  In the 1-D RANS model, the Spalart Allmaras closure model was used to model the turbulence caused by eddies within the vegetation zone and the interface between the top of the vegetation and the clear water zone. In this work, numerical simulations using 1-D RANS model are carried out using dataset obtained from the laboratory under different hydraulic conditions of varying areal vegetation densities. Three classes of highly flexible vegetation densities were simulated: low, medium and highly dense vegetation. The model predictions in terms of mean vertical stream-wise velocity profile and Reynolds Shear Stresses were compared with the laboratory flume experimental results. The 1-D RANS model performances were satisfactory for low and medium densities.  However, discrepancies were seen in the model prediction for highly dense vegetation. Hence, the hydraulic roughness parameters in the numerical model has been modified for model re-calibration to capture the position of zero-displacement of velocities. Using the modified parameters, the velocity profiles and the Reynolds Shear Stresses were predicted with very low uncertainty.
Keywords: Zero-displacement parameter, 1-D RANS model, Reynolds shear stresses, areal density, flexible vegetation

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Research Paper

Performance-Based Evaluation of Steel Fibre Reinforced Normal- and High-Strength Concretes Using Statistical Analysis of Experimental Database

Adewuyi AP, and Animbom O.

J. Civil Eng. Urban., 14(3s): 238-246, 2024; pii:S225204302400025-14

DOI: https://dx.doi.org/10.54203/jceu.2024.25

Abstract
The widespread acceptance of concrete can be attributed to its unique characteristics, despite inherent drawbacks such as brittleness and weak tensile strength. The study was aimed at evaluating the optimal content and characterization of steel fibres required to impede crack propagation and enhance overall strength of concrete. The influence of critical factors like fibre content, length, diameter, and volume fraction on the performance of steel fibre reinforced concretes (SFRC) through statistical analysis of 209 experimental data. The influence of these factors on the compressive, flexural, and tensile strengths of concrete was analyzed as a function of the mean and coefficient of variation of the normalized strength values. The study found that steel fibres in concrete produced success rates of 67.9% (7.1% average strength improvement = ASI) in compressive strength, 78.5% (38.2% ASI) in flexural strength and 84.2% (23.8% ASI) in tensile strength. The study further separately examined the impact of steel fibres on both normal strength concretes (NSC) and high strength concretes (HSC). The findings indicated an overall success rate of 60% (6.97% ASI), 69.9% (38.36% ASI), and 75.6% (23.59% ASI) for compressive, flexural, and split tensile strength, respectively, in NSC. However, higher degree of strength enhancement of 74.0% (7.16% ASI), 84.8% (39.21% ASI), and 86.6% (23.51% ASI) were recorded for compressive, flexural, and split tensile strength, respectively in HSC. The research underscores the effectiveness of incorporating steel fibres as a reinforcement strategy in enhancing various strength aspects of concrete.
Keywords: Fibre reinforced concrete, steel fibres, compressive strength, tensile strength, flexural strength, normalized strength, average strength improvement.

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Research Paper

Empirical Scrutiny of Geopolymer Concrete Containing Locally-produced Superplasticizer under Varied Temperatures

Agashua LO, Arum C, Oluyemi-Ayibiowu BD, and Ikumapayi CM.

J. Civil Eng. Urban., 14(3s): 247-262, 2024; pii:S225204302400026-14

DOI: https://dx.doi.org/10.54203/jceu.2024.26

Abstract
Cement manufacturing companies contribute greatly to carbon-dioxide emission during production, hence there is need for novel eco-friendly or biodegradable cementitious material, which has the same strength and also durable. Geopolymers which are eco-friendly waste materials, which can also reduce construction cost are therefore considered for this purpose. The geopolymer stabilizing materials, fly ash (FA), kaolin clays powder (KCP), rice husk ash (RHA), and alkaline activator (procured sodium silicate, waste-created sodium silicate and sodium hydroxide) were added at 0, 2.5, 5, 7.5, and 10%, to the naturally created superplasticizer geopolymer concrete (GPC), so as to solve the problem of workability and efflorescence associated with fly ash based GPC. FTIR results shows major absorbance band at the region between 950 and 3250 cm−1. It means that addition of the naturally made superplasticizer to the geopolymer concrete lowered the viscosity and increased the flow behavior of concrete. The geopolymer concrete consists of super plasticizer (1.5%) and optimum of various binders i.e. 5% FA + 7.5% KC + 10% RHA + aggregate + water. At temperature above 70°C both compressive strength and weight decreases, for naturally made and purchased sodium silicate. The optimal geopolymer product showed substantial strength and durability enhancements at 70°C temperatures, with strength and durability values decline above 70°C, indicating material deterioration. A positive correlation between hot-state temperature, strength and durability properties was also established. The R2 of the Feret on the test set reaches 0.967, indicating its excellent predictive performance.
Keywords: Rice Husk, Fourier Transform Infrared Spectroscopy, Waste-created sodium silicate, Superplasticizer; Eco-friendly

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Research Paper

An Analysis of Water Demand of the Rural Population within the Iishana System, Namibia

Eino J, Katte VY, Busari AO, Pires EES, Johannes P, Fahrenberg M, Reinhardt CI, Jüpner R and Schulte A.

J. Civil Eng. Urban., 14(3s): 263-270, 2024; pii:S225204302400027-14

DOI: https://dx.doi.org/10.54203/jceu.2024.27

Abstract
The Namibian people, particularly, those living within the Iishana system, which is a subset of the Cuvelai Basin, often encounter recurrent floods and droughts. After each rainy season, the Iishana system dries up gradually, hence, water for both agriculture and potable purposes becomes crucial. With the anticipated new water infrastructural development and rehabilitation of existing ones, it will be necessary to ascertain the water demand of the rural population, for the quantification of the supply potential to improve water availability. This study adopts historical water consumption per capita recommended within the Iishana system to determine the rural population demand. Considering a thirty years’ population projection, the water demand of the Iishana system is properly estimated. Moreover, the historical hydrological dataset daily data for the period 2012-2021 was used for the analysis. The current demand is estimated at 2,479 cubic meters per day. The projections of water demand for the rural population for 2033, 2043, and 2053 are 0.9, 0.5, and 0.1 Mm3/year, respectively. More so, the surface water resource potential of the system is estimated at an average of 300 mm/year. The region loses more water through evaporation than it receives in the wet season. Around 2500 mm of water evaporates from the surface annually, giving a water deficit of 2200 mm/year. The region's flat, shallow landscape, high evaporation rate, and the inadequacy of infrastructure have made the area vulnerable in terms of water security for both agricultural and potable purposes, resulting in droughts after the rainy season. With these findings, it is recommended to build water infrastructures within the region to improve the well-being and livelihood of rural communities.  
Keywords: Water demand, water supply, rural population, per capita demand, Iishana system, Namibia

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Research Paper

Meeting the Sustainability Emergency in Built Environment Curricula through Tripartite Pedagogy Quasi-Experimentation

Ewurum NI, Aguome NM, Kelobonye K, Emoh FI.

J. Civil Eng. Urban., 14(3s): 271-277, 2024; pii:S225204302400028-14

DOI: https://dx.doi.org/10.54203/jceu.2024.28

Abstract
This study evaluates the effectiveness of a tripartite pedagogy framework integrating specialized tracks, optional minors, and experiential learning to enhance sustainability education in built environment curricula. Employing a mixed-methods quasi-experimental design, the research assessed 239 industrial training students in Enugu, Nigeria. Results from the t-test demonstrate significant improvements in sustainability knowledge post-intervention and high interest in optional sustainability courses. Repeated measures of ANOVA revealed substantial enhancements in students' ability to apply sustainability concepts over time. Qualitative data highlighted practical challenges in experiential learning, including resource constraints. The findings provide empirical support for the tripartite approach, extending previous research by quantifying impacts on practical skills development. This study contributes to the limited body of evidence on integrated sustainability education interventions in the Global South, demonstrating significant improvements in students' sustainability knowledge and application skills through a tripartite pedagogy framework. The findings highlight the potential of specialized tracks, optional minors, and experiential learning to bridge the gap between academic preparation and industry needs. It is recommended that educational institutions prioritize these integrative approaches and address resource constraints to enhance the effectiveness and scalability of sustainability education in built environment curricula.
Keywords: Building Research Establishment Environmental Assessment Methodology, Built environment curricula, Experiential learning, Optional minors, Specialized tracks, Sustainability competencies

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Research Paper

Enhancing Water Level Prediction through a Hybrid Feature Selection Approach

Tshireletso T, Ouma Y, Moalafhi D, and Anderson G.

J. Civil Eng. Urban., 14(3s): 278-282, 2024; pii:S225204302400029-14

DOI: https://dx.doi.org/10.54203/jceu.2024.29

Abstract
Accurate prediction of water levels (WL) is essential for various applications, from flood management to environmental monitoring. In this study, an enhanced approach to feature selection tailored for water level prediction models is presented. Our method integrates Mutual Information and Recursive Feature Elimination with Cross-Validation (RFECV), augmented by the Non-Dominated Sorting Genetic Algorithm II (NSGA-II), to systematically evaluate and refine subsets of features. Mutual Information facilitates the identification of relevant feature dependencies, while RFECV iteratively eliminates less informative features to optimize predictive accuracy. The inclusion of NSGA-II further enhances the selection process by considering multiple conflicting objectives simultaneously, such as maximizing R2 score and minimizing the number of selected features, RMSE, and MAE. Through extensive experimentation and validation on real-world datasets, we demonstrate the effectiveness of our hybrid feature selection approach in capturing intricate relationships within the data, leading to significantly improved predictive performance in water level prediction models.
Keywords: Mutual Information, Recursive Feature Elimination with Cross validation, Non-Dominated Sorting Genetic Algorithm II

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Research Paper

Investigation of Performance of Copper Slag and Ore Tailings Novel Trial Self-compacting Concrete Mixtures

Fidler A and. Oyejobi DO.

J. Civil Eng. Urban., 14(3s): 283-288, 2024; pii:S225204302400030-14

DOI: https://dx.doi.org/10.54203/jceu.2024.30

Abstract
A non-conventional concrete with the properties of flow-ability, filling-ability, and passing-ability without any need for mechanical compaction but flow under self-weight is known as self-compacting concrete. This study developed trial mixtures for self-compacting concrete (SCC) using locally available waste products. The copper slag and ore tailings from Bamangwato Concessions Limited Mine in Selebi-Phikwe, Botswana were used as source of fine aggregate, and fines substitute. Eight mix proportions were developed with the quantities of cement, granite, copper slag, ore tailings and water-cement ratio as variables. The mix proportions were developed in accordance with recommendations from American Concrete Institute (ACI 237R-07) and fresh SCC properties (flow ability, passing ability, filling-ability, and segregation) were performed to assess the performance of the mixes. It was observed that the range of slump flow values were between (500 – 750 mm), V-funnel values (1.46 – 7.46 s), passing-ability of (0.76 – 1.0). The hardened properties of SCC (strength and density) were between 8.1 and 33.3 MPa, and 2093 to 2406 kg/m³) respectively. It could be concluded that SCC produced from mine wastes (copper slag and ore tailings) is found suitable for the use in unreinforced and normal concrete applications.
Keywords: Self-compacting concrete, filling-ability, flow-ability, passing-ability, slump flow, segregation and compressive strength.

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Research Paper

Efficacy of Direct SPT-Based Pile Design Methods in Residual Soils of Southern Africa

Masilo T and Dithinde M.

J. Civil Eng. Urban., 14(3s): 289-294, 2024; pii:S225204302400031-14

DOI: https://dx.doi.org/10.54203/jceu.2024.31

Abstract
Direct SPT-based pile design methods are very popular these days despite the fact that many of such methods are based on small databases of pile load tests. Due to the dependence of soil behaviour on geological setting and site specific conditions, it is possible that some of the methods do not produce good prediction of pile capacity. Accordingly this paper presents the evaluation of two SPT-based pile design methods in residual soils against a pile load test database from the Southern African region. The methods include the (i) Franki-SA method reported in Byrne et al. (1995) and (ii) Decourt Method (1995).  The pile load tests consist of 26 cases of bored piles in residual soil with each case accompanied by SPT measurements. The SPT measurements were used to calculate the predicted capacity in accordance with the procedure for each of the two methods while the pile load tests were used to determine the measured capacity. The findings of the evaluation indicate that the Decourt method is more reliable and accurate than the SA method. The poor performance of the SA methods suggests further studies to develop specific calculation factors for base and shaft capacities in residual soils.
Keywords: SPT-based pile methods, Load Bearing Capacity, Pile Load Test, Chin extrapolation method, Terzhagi’s 10% criteria, Rank Index.

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Research Paper

Behaviour of Fly-Ash Geopolymer Mortar in Simulated Environments

Oyejobi DO.

J. Civil Eng. Urban., 14(3s): 295-301, 2024; pii:S225204302400032-14

DOI: https://dx.doi.org/10.54203/jceu.2024.32

Abstract
Concrete and mortar usually found themselves in normal and harsh environments. The environment has great influence on the mechanical and durability behaviours of the concrete. In this study, fly ash was processed using circular economy concept and subsequently used as precursor for geopolymer mortar. The fly ash from Morupule power plant station has previously been characterized for its physical, chemical, and microstructural properties. Based on its suitability, the fresh and mechanical properties of the geopolymer mortar were carried out, and afterward, the durability behaviour is investigated in this study. The geopolymer mortar was formulated from the mixture of fly ash, sand and alkaline activators and cured thermally at 70°C. The behaviour of the geopolymer mortar in sulphuric acid solution, sodium sulphate solution, water absorption and fire resistance properties were simulated, and their loss in compressive strength and weight were determined. The laboratory experiment indicated that geopolymer mortars are highly resistant to sulphate attack, water absorption with moderate resistance against sulfuric acid and fire resistance. The effects of varying other parameters on the performance of concrete can be looked into in the future studies.
Keywords: Geopolymer mortar, environment, durability, mechanical, fly ash, circular economy

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Research Paper

Flexural Behaviour of Concrete Beams Reinforced With Major Steel Bars under Normal and Corrosive Operational Conditions

Adewuyi AP and Eric GB.

J. Civil Eng. Urban., 14(3s): 302-310, 2024; pii:S225204302400033-14

DOI: https://dx.doi.org/10.54203/jceu.2024.33

Abstract
Quality assurance of construction materials is very fundamental for structural safety, reliability, serviceability, and durability of constructed civil infrastructure. Inflow of defective or substandard building and construction materials into the industry, particularly reinforcing steel bars, is responsible for many structurally deficient constructed facilities which often lead to failure or ultimate collapse of reinforced concrete (RC) structures. Characterization of steel rebars from two major manufacturers into Botswana construction industry, designated herein as M1 and M2, were conducted as a basis for the evaluation of the quality assurance and control of the products. The flexural behaviour of their respective RC beams, designated herein as B-M1 and B-M2, of dimension 150 × 200 × 3000 mm and subject to four-point loading tests were determined under normal and artificially induced corrosion conditions to assess the influence of steel rebars M1 and M2 on the stiffness and load-carrying capacity. The average yield strengths of steel reinforcing bars were 427 N/mm² for M1 and 459 N/mm² for M2. The moduli of elasticity for M1 and M2 were 203 GPa and 205 GPa, respectively. The percentage elongation was found to be 7.93% for M1 and 7.24% for M2. The flexural strength of beams reinforced with M1 was 7% and 16.5% lower than RC beam with M2 under normal and accelerated corrosion of 5% of NaCl solution for 60 hours condition, respectively. The flexural behaviour of RC beams reinforced with B-M1 had a lower flexural strength under both normal and corrosive environmental conditions as compared to B-M2. The flexural strength of B-M1 had reduced from 48.5 N/mm² to 41.0 N/mm², while B-M2 reduced from 52.2 N/mm² to 49.2 N/mm². This represented loss of load-carrying capacity of 15.4% and 5.8% for B-M1 and B-M2 respectively due to exposure to corrosive environment. The findings revealed disparity in bending capacity due to the low interfacial bonding due to reduced relative rib areas. A more intensive quality control of imported steel should be ensured at the ports of entry by relevant regulatory agencies.
Keywords: Flexural capacity, Sfiffness, Reinforcing bars, Relative rib area, Interfacial bonding, Accelerated corrosion, Ultimate load.

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Research Paper

The Use of Machine Learning Approach to Predict Pile Capacity in Non-Cohesive Soils

Palalane L and Dithinde M.

J. Civil Eng. Urban., 14(3s): 311-317, 2024; pii:S225204302400034-14

DOI: https://dx.doi.org/10.54203/jceu.2024.34

Abstract
Existing theoretical and empirical pile design methods cannot accurately model the complex interaction between piles and soil. Consequently, there is a growing trend towards utilizing machine learning techniques to better capture the nonlinear soil-pile interaction. This paper aims to predict the capacity of bored piles in cohesionless soils using a machine learning approach. The machine learning algorithm was trained using a database of 18 bored pile cases in non-cohesive soils and validated with a separate dataset of 8 bored piles in cohesionless soil. Moreover, the performance of the machine learning method was compared with that of a traditional pile design method (i.e., SA-SPT method) in Southern Africa. The evaluation was based on the ratio of measured capacity to predicted capacity (Qm/Qp) statistics and the coefficient of determination (R2). The results showed an R2 of 0.89 for the machine learning method compared to 0.85 for the SA-SPT method, indicating the superior accuracy of the machine learning approach in predicting pile capacity.
Keywords: Machine learning, SPT-based pile methods, Load Bearing Capacity, Full-scale Load Test, Chin extrapolation method, Terzhagi’s 10% criteria.

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Research Paper

Geotechnical characterization of the Manyana black cotton soils in Botswana

Marumo MN, Lebitsa G, Malumbela G.

J. Civil Eng. Urban., 14(3s): 318-324, 2024; pii:S225204302400035-14

DOI: https://dx.doi.org/10.54203/jceu.2024.35

Abstract
The Manyana Village is divided into two types of soils. The center of the village is covered with sand that overlays clays from weathered dolerite whilst the eastern side is covered with exposed clays. Houses constructed on the eastern side of the village are prone to severe cracking attributed to the black cotton soils. The paper hints at shrink-swell mechanism of black cotton soils as a possible explanation for the cracking observed on the houses. Three laboratory methods of identifying and characterizing expansive soils are discussed followed by use of Dynamic Cone Penetration (DCP) in field-testing as well as use of indicator tests and particle sizing in the laboratory. The experimental results have shown a high field moisture content of (18 to 27%) in the eastern part of the village which was three times larger than moisture content at the village center. The clays had a plasticity index range of 12% to 30% with a clay content of 21% to 47% whilst the sandy areas were non-plastic with a clay content of at most 4%. The clay minerals identified from the samples tested were vermiculite, illite, kaolinite and montmorillonite. The soil samples from the village had low potential expansiveness whilst most samples on black cotton soil had a medium to high potential of expansiveness. The bearing capacity estimated from DCP data at depths of 1m throughout the village were 72 kPa to 275 kPa under dry conditions. A draft plasticity index map of Manyana village was produced based on the results of the investigation, the next step is to investigate the effectiveness of different soil stabilization methods for this area and taking in to consideration cost, durability and environmental impact.
Keywords: Black cotton soil, Cracking, Moisture content, Plasticity index, Bearing capacity.

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Research Paper

Evaluation of the Compressive Strength and Sorptivity of Pozzolanic Concrete Containing Calcined Termite Mound

Ikumapayi CM, Arum C, Arum V, Omoyajowo MO, Omotayo OO, and Ohwofasa OJ.

J. Civil Eng. Urban., 14(3s): 325-333, 2024; pii:S225204302400036-14

DOI: https://dx.doi.org/10.54203/jceu.2024.36

Abstract
Pozzolans have long been established as viable materials for the partial replacement of cement in concrete. However, the extent to which they can be used is still under investigation. Pozzolans do not in themselves have cementitious value but can react chemically with calcium hydroxide and moisture to produce cementitious compounds. Pozzolanic concretes have been reported to have varied properties in term of compressive strength and durability properties which need to be ascertained. This research focuses on Calcined Termite Mound (CTM) and its influence on the compressive strength and sorptivity of concrete. Several tests were carried out to ascertain the physical, chemical, and mineralogical properties of CTM and conventional concrete constituents. Some of these tests include bulk density, setting time, aggregate crushing value (ACV), aggregate impact value (AIV), slump test, X-Ray Fluorescence (XRF), X-Ray Diffraction (XRD), sorptivity, and compressive strength tests. Compressive strength tests results for concrete containing Ordinary Portland Cement (OPC) and CTM cement blends show that CTM has higher silica content compared to OPC and can be classified as Class-N pozzolans It is also richer in calcium oxide. The study also reveals that CTM has an optimum replacement level of 5% with strength of 13.4 MPa at 28 days, which is higher than the 12.4 MPa of control concrete. Also, the result of sorptivity test for OPC-CTM blended concrete gave lower resistance to sorptivity. Regression models were developed to predict the compressive strengths of OPC-CTM concrete as a function of % replacement level and curing age.
Keywords: Calcine termite mould; Compressive strength; Pozzolanic concrete; Sorptivity.

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Research Paper

Estimation of Water Demand for the Rural Population in the Angolan Part of the Iishana System

Chiweyengue AM, Serrão Pires EE, and Afis BO.

J. Civil Eng. Urban., 14(3s): 334-338, 2024; pii:S225204302400037-14

DOI: https://dx.doi.org/10.54203/jceu.2024.37

Abstract
The Iishana is a shallow, low-slope channel system located in the Cuvelai basin (Southern Angola and Northern Namibia), characterised by drought and flood cycles due to erratic climate variability. The knowledge gap regarding the actual water needs in the area, the number of residents within the system, the seasonal influence of cattle migration, and poor socio-economic conditions, make the population even more vulnerable to droughts. The main objective of this study is to estimate the water demand by the rural population on the Angolan side of the Iishana system, attempting to fill the knowledge gap. To reach the demand estimates, a mathematical procedure within a GIS environment was used, in QGIS 3.32.2 software, relating population gridded and meteorological data to make the necessary calculations. In 2023, it estimated consumption for intake and personal hygiene of 4.7 Mm3, 6.3 Mm3 for 2033, 8.4 Mm3 for 2043 and 11.3 Mm3/year for 2053. In recent years there have been rainfall records throughout the Iishana system, at an average of 518 mm/annum, but high temperatures accelerate water evaporation. Due to the topographical conditions, the waters are drained by gravity to the south of the basin (Republic of Namibia), causing a greater shortage in the dry season on the Angolan side, the study targets the estimation of water demand and the concept of rainwater harvest and sustainable water infrastructure to supply safe drinking water to equalise water demand and reduce vulnerability to climate change. These early findings may provide a basis for developing sustainable water infrastructure and use plans to improve the livelihoods of the resident population within the basin.
Keywords: Water demand, Water supply, Iishana system, Cuvelai Basin, Water infrastructure.

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Proceedings of The International Conference on Civil Engineering for Sustainability and Resilience in the 21st Century and Beyond (ICCESR-2024)

University of Botswana, Gaborone, Botswana,

25–26 June, 2024

The International Conference on Civil Engineering for Sustainability and Resilience in the 21st Century and Beyond (ICCESR-2024), organized by the Department of Civil Engineering at the University of Botswana, brought together academia, practitioners, researchers, policy makers and regulators to discuss emerging and pertinent issues relating to sustainability and resilience in Civil Engineering and related disciplines. The conference thematic areas encompassed developments and improvements in innovative designs, construction and smart technologies and the formulation of appropriate policies in the face of climate change to ensure sustainability and resilience.

This Special Issue of the Journal of Civil Engineering and Urbanism is a compilation of the proceedings of the ICCESR-2024 conference.

ICCESR-2024 has been held as authorized partner for the Scienceline International journal (Journal of Civil Engineering and Urbanism).

Dr. Damilola Oyejobi

Secretary, ICCESR-2024 Organizing committee

https://conferences.ub.bw/index.php/ICCESR/ICCESR-2024

Email: Oyejobido@ub.ac.bw; iccesr-2024@ub.ac.bw

Prof. Dr. Yashon Ouma

CONGRESS CHAIRMAN

Email: Oumay@ub.ac.bw

List of guest editors and reviewers

Prof. Yashon Ouma
Department of Civil Engineering, Faculty of Engineering and Technology, Private Bag UB 0061, University of Botswana, Gaborone, Botswana

Prof. Ssegawa, Joseph
Department of Civil Engineering, Faculty of Engineering and Technology, Private Bag UB 0061, University of Botswana, Gaborone, Botswana

Dr. Damilola Oyewumi Oyejobi
Department of Civil Engineering, Faculty of Engineering and Technology, Private Bag UB 0061, University of Botswana, Gaborone, Botswana

Dr. Ali A Firoozi
Department of Civil Engineering, Faculty of Engineering and Technology, Private Bag UB 0061, University of Botswana, Gaborone, Botswana

Prof. Mohammed Jameel
King Khalid University, Saudi Arabia

Prof. Modupe Jimoh
Department of Civil Engineering, University of Warwick, United Kingdom

Prof. Bolanle Ikotun
University of South Africa, UNISA, South Africa

Prof. Abdulkadir Taofeeq Sholagberu
Department of Water Resources and Environmental Engineering, University of Ilorin, Ilorin, Nigeria

Dr. Ajibola Ibrahim Quadri
Federal University of Technology, Akure, Ondo State, Nigeria

Dr. Daniel Oguntayo
Department of Civil Engineering, Landmark University, Omu-Aran, Kwara State, Nigeria

Mr. Lawrence Zahemen Tuleun
Department of Water Resources and Environmental Engineering, University of Ilorin, Ilorin, Nigeria

Dr. B. Madzikigwa
Department of Civil Engineering, University of Botswana, Gaborone, Botswana

Dr. B. Wilson
Department of Civil Engineering, University of Botswana, Gaborone, Botswana

Dr. Lopang Maphale
Department of Civil Engineering, University of Botswana, Gaborone, Botswana

Dr. B. Nkwae
Department of Civil Engineering, University of Botswana, Gaborone, Botswana

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This work is licensed under a Creative Commons Attribution 4.0 International License (CC BY 4.0)