Theses and dissertations (Engineering and Built Environment)

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Building information modelling technologies for intelligent road engineering design, construction and digital twinning
(2023-09) Yunos, Shuaib; Allopi, Dhiren
Roads form an integral part of civil infrastructure, providing safe and reliable access from a point of origin to a destination. With the rapid growth in population, urbanisation, and the pursuit of smart cities, the pressure on effective road design, construction, and maintenance is ever-increasing, with sustainability and innovation being at the focal point to derive better and more intelligent ways to accomplish this infrastructure requirement. With this influx of demand, traditional processes are put under strain, resulting in roads being designed inadequately, impacting the safety and service, exploration of minimal alternative routes due to time pressure or lack of information, material wastage affecting design sustainability and construction cost, and poor maintenance affecting safety and design life. With the progression in technology, building information modelling (BIM) is an intelligent 3D model-based process that gives architecture, engineering, and construction (AEC) professionals the insight and tools to plan, design, construct and manage buildings and infrastructure more efficiently. BIM has been implemented, adopted, and mandated by many countries across the world, seen as an intelligent, innovative necessity for enhanced civil infrastructure design, construction, and maintenance. This leads to the question of BIM on civil infrastructure projects, with the focus being roads, and how would it compare to the traditional way of accomplishing road projects. In this regard, an in-depth investigation into the application and impact of BIM technologies across a typical road project had been conducted. This was achieved by describing the processes associated with a typical project when employing a traditional and BIM approach across 9 stages of the project lifecycle. This methodology effectively allowed for a detailed comparison between the two approaches, with the findings collated. The dissertation also expands on what is BIM, its levels, dimensions, benefits, its application on projects across various continents, its role in digital twinning and smart cities, its presence and development globally, its presence and development in Africa, as well as the hurdles experienced in its adoption and implementation and recommendations on how to overcome them. The conclusion arrived at was that BIM provides a plethora of advantages across the road project lifecycle, resulting in innovative, economical, and sustainable civil infrastructure, paving the way to enhanced operations and maintenance and digital twinning in the pursuit of smart cities, correlating with BIM being mandated by countries across the globe and various literature confirming its positive impact. The BIM approach outperformed the traditional approach across all stages of a typical road project lifecycle, conforming to the MacLeamy curve. The BIM technologies applied to derive and illustrate this conclusion were BIM technologies developed by Autodesk and the Devotech Group of Companies. It was also observed that whilst BIM has been around since the 1970s, BIM is still seen as a new concept, particularly in the civil infrastructure industry, and whilst professionals acknowledge its advantages, they are resistant to change, overwhelmed by how to become BIM ready, or do not know where to turn to for guidance, particularly in South Africa, Africa, and other developing countries. Other main challenges observed were those of education, training and upskilling, upfront cost, and the absence of a BIM mandate, as well as challenges specific to Africa were unpacked such as infrastructure gaps, skill gaps, digital division, and digital transformation.
A case study : evaluation of adjudication as a dispute resolution method : NEC and FIDIC contracts
(2022-09-29) Mkhize, Zizodwa Zizo; Allopi, Dhiren
Construction development plays an important role in the development of South Africa, not only in respect of its built infrastructure, but also in its broader economic and social development. It also creates employment prospects on a broader scale. Construction contract adjudication has been introduced in South Africa by means of four forms of contracts endorsed by the Construction Industry Development Board. Amusan and Owolabi (2014) mention that the unfavourable outcomes of project objectives in terms of time, cost and quality are as a result of delays in construction projects. Although disputes may be unwanted, having suitable knowledge to manage disputes when they happen often provides better results for the disputants and the project. The study was conducted in an electricity generation organisation, which has various divisions and departments that develop and execute projects. Complex projects that require multiple interdivisional or external stakeholder interfaces are planned, developed and implemented in the Group Capital Division (GCD). The purpose of this research study was to evaluate whether the causes, practices and outcomes of the construction contract adjudication method for the Fédération Internationale des IngénieursConseils (FIDIC) were similar to those of New Engineering Contract (NEC) used for infrastructure construction projects. A mixed method by means of a case study was adopted to answer the research questions. Data were collected from an analysis of 33 study documents related to FIDIC and NEC contract case studies. The results of the study showed the following: 1) There are comparable causes of disputes among the two contracts, even though they vary in terms of ranking on each contract; 2) some of the disputes referred to adjudication could have been avoided; and 3) FIDIC and NEC complied with the adjudication practice, and the outcomes of the adjudications differed based on the merits of each case.
Characterisation of concrete with expanded polystyrene, eggshell powder and non-potable water : a case study
(2023-05) Mncwango, Bonke; Allopi, Dhiren
Urbanisation has brought many benefits but it has also highlighted the global lack of housing alongside global natural resource scarcity. Lack of housing on the surface appears to be a singular problem, however in reality it represents a number of society’s biggest challenges such as crime, pollution (as a result of inadequate waste disposal strategies), unhygienic living conditions, as well as numerous health problems. Governments across the world have made various attempts at addressing the issue of lack of housing, including embarking on large scale social and public housing initiatives, building smaller homes for the homeless, as well as removing certain regulatory barriers to allow more houses to be built at a reduced timeframe. These advances have assisted many individuals and families globally, however, there are still many individuals and families that government housing-aid or housing initiatives have not yet reached. These individuals and families are faced with solving their housing crisis on their own, with their own resources. Globally, concrete remains a supreme building material in the construction industry and therefore is a primary factor of consideration for solving the housing crisis, especially for those who have no financial assistance or aid from government. Concrete’s composition is simple: cement, fine aggregate, coarse aggregate and water. The intricate interaction between all four components is meant to stand the test of time. Unfortunately, it is not only the earth’s diminishing natural resource reserves which are causing a decline in the popularity of conventionally produced concrete, but it is also the irreparable harm that it is causing to the environment. The process of concrete production requires large volumes of cement, and cement remains one of the biggest producers of carbon dioxide. Carbon dioxide is a greenhouse gas which in excessive amounts creates a cover that traps the sun’s heat energy in the atmosphere. Another major criticism of conventional concrete is the requirement that it be produced with clean water which is of a drinkable standard. This criticism is justified when considering the extreme water shortages that are experienced by many low to middle income countries around the world. The amount of financial and human resources that local authorities invest in cleansing water to bring it to a drinkable standard is often overlooked. It is obvious that it is less expensive to use water directly from a river in its natural state than using it after it has undergone numerous cleansing processes by local authorities. There have been a notable number of advances in making concrete more resource-efficient and environmentally friendly. These include the advent of lightweight concretes such as expanded polystyrene concrete. Expanded polystyrene concrete not only saves the amount of aggregate that would normally be required in conventional concrete, it also has excellent acoustic and thermal properties, thereby reducing energy consumption which in turn saves money. However, even with such excellent properties, expanded polystyrene concrete still fails to address two of concrete’s major criticisms which are related to the amount of cement used as well as the amount of clean potable water required for mixing. Therefore, by building on the qualities of expanded polystyrene concrete, this research investigates the potential of lowering the amount of cement required in a concrete mix through the use of eggshell powder. Eggshells are a waste product found everywhere in the world and are readily available in almost limitless quantities. The use of eggshells in concrete to lower the amount of cement required will not only achieve a reduction in the amount of carbon dioxide that is produced in the process of producing concrete, it will also assist in contributing toward solving the escalating waste disposal crisis that currently exists for many waste types such as eggshells. It is common for communities to reside close to a river or a natural flowing watercourse, so this research included river water as a variable. Four different concrete mix scenarios were tested to ascertain through experimentation whether the strength properties of concrete that contains expanded polystyrene, eggshell powder and natural river water in various proportions could in any way compare to a conventionally produced concrete mix. In order to comprehensively study material behaviour in this case, sieve analysis, bulk density, fineness modulus, moisture content as well as specific gravity tests were performed on all aggregates used. Furthermore, in order to achieve the required analytical depth for the materials being studied, x-ray diffraction and energy dispersive spectroscopy tests were conducted. As a means of conducting further trend analysis on the different experimental mixes, logarithmic regression models were developed. Through analysis of the output attained from the aforementioned strategies, this research study found that when cement was substituted by eggshell powder at a percentage of 5 % and simultaneously when coarse aggregate was also substituted by expanded polystyrene at a percentage of 5 %, all mixed with non-potable water, the compressive and flexural strength outcomes marginally differed from the strength outcomes of conventionally produced concrete. Furthermore, the substitution of stone by EPS at a percentage of 10 % when mixed with river water was comparable to the substitution of stone by EPS at a percentage of 10 % when mixed with potable water. The results showed that there was a difference of not more than 1.4 MPa and 0.3 MPa in compressive and flexural strength respectively amongst the averages obtained at each age tested. Study results show that the substitution of potable water by non-potable water reduced both the compressive and flexural strength of the concrete when the mix did not contain eggshell powder. However, when eggshell powder was included in the mix, the strength outcomes of the compressive and flexural strength of the concrete mix was comparable to that of conventionally produced concrete. There may be many reasons why it is important to not deviate from convention in the production of numerous products such as concrete; nevertheless, the value of experimentation as demonstrated in this research is that experimentation can give rise to a variety of innovations accompanied by a wealth of solutions to the environmental and socio-economic issues that the world is currently faced with.
Determination of the most appropriate bus rapid transit system for the eThekwini Municipal Area
(2014) Adewumi, Emmanuel Olusegun; Allopi, Dhiren
Invariably, a high percentage of the population of South Africa depends on public transport. In order to continue to satisfy commuters in terms of comfort, travel time, reliability of service and traffic congestion, there is a need to improve the efficiency of moving passengers to reduce travel time, delay time and number of stops. In the quest for advancement and improvement in public transport, many countries now embark on Bus Rapid Transit (BRT) systems based on the successful implementation of the system by cities like Curitiba (Brazil) and Bogota (Columbia). Government departments/transport authorities are often faced with the challenge of selecting the most suitable BRT system relative to the unique features of its transport demands and urban layout. Hence, this study proposes the determination of the most appropriate BRT system for the eThekwini Municipal Area (EMA). An in-depth literature review was conducted in order to determine the most adoptable BRT system amongst median, kerb side and segregated BRT systems, taking into consideration cost implications, safety of the passengers, pedestrian crossing, physically challenged commuters, vehicle option and manoeuvres. Physical assessment and critical review of the current operating BRT systems in Johannesburg, Cape Town and Port Elizabeth in South Africa was employed in this study as well as a critical comparison among these systems. The pros and cons of the three functional BRT systems in South Africa were stated and a way forward for EMA was recommended. Lastly, an assessment of the proposed BRT system in EMA was conducted on the existing Phase 1 and the remaining three phases. The review conducted was based on route inspection, access to property, factors considered in the selection of a BRT system, demand analyses of the routes and the evaluation of Johannesburg, Cape Town and Port Elizabeth BRT systems. Guidelines were also provided for the remaining proposed BRT routes which could be adopted by the eThekwini Transport Authority (ETA) in order to enhance a better performance in EMA over the three functional BRT systems in South Africa using the aforementioned criteria.
The development of a teaching tool using Sketchup to enhance surveying competence at the Durban University of Technology
(2015) Stuart, Darryl George; Landman, J. C.; Allopi, Dhiren
Surveying concepts are difficult to understand, especially when students are exposed to surveying for the first time. Surveying is best understood when linked to field applications; however, students are only exposed to surveying and related field operation procedures during practicals. Two-dimensional (2D) explanations of surveying equipment used is shown during class lectures, which makes understanding of field procedures difficult to teach and learn during normal class lectures. A new approach to lecture delivery is required to make lectures more interesting and visually stimulating via three-dimensional (3D) animated models of levelling equipment and simulation of field observations and data collection. Additionally the learning of basic surveying concepts cannot be limited to field practicals, but in conjunction with learning that takes place in the classroom. Students' ability to properly learn the correct use of surveying equipment during time-tabled practicals is limited. The students do not have sufficient time in their normal scheduled practicals to learn to use surveying equipment to the required proficiency level. The main objective of this research was to deal with these inadequacies by exposing students to (3D) animated models of surveying equipment during lectures and the corresponding field applications created within SketchUp software. Students were exposed to these animated 3D models during lectures, so that their actual field operation and application could be simulated. Quantitative analysis of the student achievement data revealed that there was a significant difference between the test scores of the control and experimental groups. Additional analysis of the developed Likert-type scale questionnaire revealed that students' had a positive attitude towards the teaching tool.
The development of road safety assessment screening procedures for the City Tshwane Metropolitan Municipality
(2020-06) Sarjoo, Arvin Ramsunder; Allopi, Dhiren
The word “accident” is a familiar term used to describe a collision involving one or more transportation vehicles that results in property damage, injury or death. The term implies a random event that occurs due to no specific reason other than human error or unforeseen circumstances. The American National Highway Traffic Safety Administration (NHTSA) suggests replacing the word “accident” with “crash” as the word “crash” implies that the collision could have been prevented or minimised by improving driver behaviour, vehicle design, roadway geometry or the environment (Garber and Hoel 2015: 150). In the global context, South Africa, as is characteristic of many developing countries with limited resources, faces the challenge to proactively managing, reducing and eliminating the high incidence of road crashes, injuries and fatalities. Due to an absence of routine Road Safety Assessment and Audit procedures within the relevant departments at the City of Tshwane Metropolitan Municipality (CTMM), the main aim of this research was to develop procedures with measurable benefits which would promote a safer road environment. The data analysis and findings describe statistically significant relationships between Average Daily Traffic (ADT) as the independent variable and Accident Frequency as the dependant variable. The linear regression models and equations as developed allowed for the prediction of crash rates and the prioritisation of CTMM road safety projects. The findings indicated significant increases in accident rates on higher order roads (typically traffic signalled controlled intersections) with factors such as a greater number of intersection conflict points, greater pedestrian volumes and increased intersection saturation or volume/capacity levels contributing to higher accident rates. Intersection controls and traffic safety measures such as traffic circles, traffic signals, and traffic signs were assessed for effectiveness in reducing the Rate of Accidents per Million of Entering Vehicles (RMEVs). The research highlights the vulnerability of Non-Motorised Transport (NMT) (particularly pedestrians) which contributed to approximately 40% of all accident fatalities (Department of Transport 2016: 31). The recommendation therefore is for a road safety assessment and screening process to focus and allocate greater resources in the effort to proactively reduce the number of pedestrian fatalities.
Durban Container Terminal role in achieving national development plan goals on sustainable development
(2024-05) Ntuli, Muziwokuthula Nkanyiso; Allopi, Dhiren
Durban Container Terminal (DCT) operations contribute significantly to emission release. DCT operations directly threaten sustainable development and South Africa’s Sustainable National Development Plan (NDP) goals. Sustainable port development aims to create scenarios for “Ports of the Future” that are green, sustainable and have minimal or no impact on the environment. The problem statement is defined as DCT's role in failure to achieve sustainable development targets set by the NDP and the United Nations (UN). The current DCT operation setup promotes an increase in cargo handling coupled with numerous socioeconomic activities, which is a constant source of increasing pressure on the limited natural resources and a continuous threat to sustainable development in the Durban areas. The aim and objectives are to investigate and explore the reasons why DCT fails to achieve sustainable development goals set up by the NDP and the UN. The quantitative research method helped to answer questions on relationships within measurable variables to explain, predict, and control a phenomenon concerning sustainable development goals for the container terminal. The findings presented challenges and a threat to DCT if the current position concerning service requirements, costs and demands for sustainability is not addressed. The literature, studies and engineering reports illustrate the available technologies that respond to sustainable development requirements. The theory supports the critical role played by the dry port, terminal layout, and operating system in mitigating emissions release during operations. The engineering and DCT electricity consumption annual reports confirm the high consumption of energy during operations. The results from the port equipment, infrastructure, road and rail integration, and dry port explain why DCT fails to achieve the sustainable development goals set by the NDP and the UN. DCT depends on the main grid energy supply originating from fossil energy sources. This has led to 58 967tCO2e for DCT operation from equipment and electrical infrastructure. The poor rail conditions have increased temporary speed restrictions (TSRs). The lack of investment in the rail infrastructure, rail maintenance, and TSR takes away the opportunity to have a dry port and reduces the number of containers travelling by road. The DCT integrated logistics system is missing the possibility of reducing CO2 emission release by 30 085.4tCO2e. The simulating model confirmed the dominance of trucks and was followed by port equipment concerning CO2 release. The results illustrate the impact of the ineffective role of rail freight. It indicates that if the number of wagons is increased, the number of trucks on the road will decrease, resulting in a CO2 release reduction. The DCT integrated operating model assessment results explain why DCT is not realizing the national development plan’s objectives for sustainable development goals. DCT consumes high amounts of energy and contributes to CO2 emissions, primarily through road and rail freight. Ineffective operational planning and poor rail conditions significantly impact CO2 release. The DCT terminal operation itself contributes only 10% of the integrated operation's CO2 emissions, with road and rail freight releasing 90%. The simulated model highlights the dominance of trucks in CO2 emissions, followed by port equipment, and poor rail conditions preventing DCT from achieving sustainable development goals. The introduction of a dry port as an intermodal hub could promote economic growth and reduce road congestion and carbon emissions. However, the poor rail conditions make the proposed Cato Ridge/Camperdown dry port unviable. DCT's main challenges in achieving sustainable development goals are categorized into three focus areas: Affordable and Clean Energy, Decent Work and Economic Growth, and Climate Action. This analysis will help provide the best operating and sustainable development scenario for DCT, which could include the introduction of hybrid equipment, energy-saving technology, and improved rail infrastructure. Adopting a reconfigured DCT-integrated operating model is recommended since it has no significate operational changes within the DCT terminal. The reconfigured DCT integrated operations introduce a dry port and a rail infrastructure upgrade to accommodate 150 wagon trains. The reconfigured DCT integrated operating model promotes the reduction of container trucks calling for a DCT terminal, unlocking decent work and economic growth, sustainable cities, and communities within the Midlands region.
Exploring industry's contribution to curriculum design of Civil Engineering programmes at Universities of Technology : a case study of Durban University of Technology
(2015) Hariparsad, Shalindra; Allopi, Dhiren; Ramrathan, P.
Promulgation of the Higher Education Qualifications Framework (HEQF) tasks the Council for Higher Education (CHE), South African Qualifications Authority (SAQA) and Department of Higher Education and Training (DHET) and standards generating bodies (Engineering Council of South Africa (ECSA)) with guiding institutions through the implementation of the new framework. Implementation is through a phased approach spanning a five-year period beginning in January 2011 and with anticipated culmination in December 2014. As the Higher Education Framework Handbook (CHE 2011:2) states: ‘all existing institutions, public and private, offering existing and previously accredited higher education programmes will be impacted upon by this process in some manner or form, whether it be through a minor name change or a complete renewal of the programme content.’ Consequently, universities of technology (UoT’s) have embarked on a curriculum renewal process and the Civil Engineering Department of Durban University of Technology (DUT) is no different. It is within this context of participation and multiple contributory environments of different role-players that this study was founded. This research explored the Civil Engineering industry’s involvement in the curriculum renewal at DUT with the intention of understanding its contribution and influence in the renewal process and particularly in terms of curriculum design. The scope of the study was restricted to DUT Civil Engineering Department and their graduates, with subjects selected from a convenience sample of DUT Civil Engineering Department’s database of employers that have in the past and presently employ DUT graduates and/ or Work-Integrated Learning (WIL) students. The sample constituted organisations from the contracting, consulting and para-statal fields of employment. A questionnaire was designed containing both open-ended questions and rating scales that explored and probed the Civil Engineering industry level of involvement in the curriculum and curriculum renewal activities at DUT. In addition, interviews were conducted with seasoned Civil Engineering staff that have interacted with industry at various levels to gain their view of industry’s involvement with design of the Civil Engineering curriculum. Data from both questionnaires and interviewees overwhelmingly suggested that industry is not directly involved with the curriculum renewal currently underway at DUT, some respondents only gathered that such an activity was taking place through the medium of the questionnaire. This suggests that the resultant curriculum will be void of much industry engagement and influence. The nature of engagement that does occur is largely through the utilisation of DUT graduates or WIL students. Engagement occurs most commonly when curriculum issues are raised by staff at interviews of employers during WIL, suggesting that the nature of association with DUT is limited to employment of students or graduates. It is inferred that industry has very little direct input into the curriculum. DUT Advisory Board is considerably under-utilised for its intended purpose of engaging industry on curriculum issues, and its existence is unfamiliar to industry at large. As much as the Advisory Board is the most appropriate avenue to discuss curriculum issues, it has limitations in that its function is not entirely realised. The data generated also resoundingly suggests that industry is fully supportive of an inclusive participation process. Data further suggest that industry genuinely wants to be involved in curriculum discussions, and decisions for reasons ranging from participating to create more relevant course content, to contributing to creation of graduates with more appropriate employability attributes. Participants from industry further intimated that their role remains for on-site experiential learning: they provide the working knowledge to complement the academic knowledge provided by DUT. They also consider themselves to be providers of other facets that contribute to a holistic graduate, and assume further roles such as those of mentors and supervisors. The likely outcomes of their influence would be rapid engagement of graduates within the Civil Engineering field. A symbiotic relationship therefore becomes apparent between DUT and industry, where with more input into the curriculum by industry; a more work- orientated graduate is produced to better serve the needs of industry. The following recommendations emerge from the findings of this study: Since most of industry’s engagement occurs during WIL interviews, it would be prudent if a generic curriculum- based questionnaire is devised. This should be filled in by employers during student WIL visitations by staff in addition to the existing questionnaire. In doing so DUT would be proactive in literally ‘taking curriculum issues to them’. The DUT Civil Engineering Department should target those companies that have an interest in making a concerted effort by enlisting them onto the Advisory Board. From an institutional perspective DUT should be more proactive and advertise the existence of such an entity, created solely for curriculum discussions with the public, and particularly with industry. Assessments, course content and the project component of the programme generated considerable comments from industry that the Civil Engineering Department could take into consideration during the curriculum renewal process.
Exploring industry's contribution to the labour-intensive construction of low order rural community access roads
(2020) Jairam, Santosh; Allopi, Dhiren
The Government of South Africa supports labour-intensive work methodologies as a means of alleviating unemployment in South Africa. In 2004 the Expanded Public Works Programme (EPWP) was formed to promote labour-intensive work methods due to the high unemployment situation. The EPWP is a nationwide programme using public funds to encourage employment by using labour-intensive work methodologies with the intention of reducing national poverty. The programme covers four sectors. The four sectors are environment and culture, infrastructure, social and non-state. The largest component is infrastructure; roads being part of the infrastructure component provides the highest potential for employment creation. Both international and local experience has revealed that by having trained supervisory staff and a proper employment framework, labour-intensive work methods can be successfully used for projects such as roads, sidewalks, storm water drains, trenches, buildings, sanitation and water. The national government, based on this experience and due to high levels of unemployment, has encouraged the use of these type of infrastructure projects as a way of contributing to the alleviation of unemployment. “Only twelve per cent of the road sector budget is used for labour-intensive projects” (Public Works 2012b: 1). This implies that there have been no drastic changes in the extent to which labour-intensive work methodologies have been used in the road works programme. This study focused on exploring parastatals’, consultants’ and contractors’ contribution to the labour-intensive construction of low order rural community access roads in the Outer West region of eThekwini’s Municipality, KwaZulu-Natal, in accordance with the EPWP Guidelines. The population consisted of 101 individuals from the contracting, consulting and parastatal fields of employment who had worked on EPWP related labour-intensive road projects in this region. All 101 individuals were chosen as the sample size A qualitative and quantitative approach was used in this research to gather data on the contribution made by the civil engineering industry to the promotion of labourintensive road construction methods. This approach allowed for an understanding of the motivation and the experiences of consultants, contractors and parastatals regarding the design and construction management choices they have made. Data was collected via a questionnaire containing open-ended questions and rating scales from 87 civil engineering staff that were employed by parastatals, contractors and consultants who were involved in designing, constructing and managing labourintensive construction of low order rural community access roads in the Outer West region of eThekwini Municipality. In addition, interviews were conducted with same 87 civil engineering staff that were involved in designing, constructing and managing these labour-intensive road construction projects during the period from 2015 to 2019. Data collected overwhelmingly suggested that very little practically is being done to promote labour-intensive construction of low order community access roads. The nature of engagement that does occur is largely through the filling in of basic reporting forms and providing basic small scale informal training and work to labour. No standard specification document is in place to enforce labour-intensive construction of rural community access roads. The documents that are in place merely serve as guidelines and administrative data collection tools rather than helping to promote labour-intensive road construction.
The formulation and application of a gravel loss model in management of gravel roads in Iringa region, Tanzania
(2015) Mwaipungu, Richard Robert; Allopi, Dhiren
Among various gravel roads distress prediction models in existence, a gravel loss prediction model is considered critical in selecting the optimal re-gravelling schedule for effective maintenance management of gravel roads. However, due to the number of variables contributing to deterioration of gravel roads and hence gravel loss, gravel loss prediction models are not readily transferable from one geographical location to another, particularly if the locations in question differ in climatic condition, gravel material characteristics, quality of construction and maintenance, terrain, traffic characteristics and driver behaviours. Addressing the aforementioned local characteristics pose a challenge to existing international gravel loss prediction models when employed locally, resulting in inaccurate prediction of gravel loss. Hence the need for a gravel loss prediction model to be formulated locally so as to address local characteristics influencing gravel roads deterioration. The main objective of this study was to formulate locally, a statistically accurate gravel loss prediction model for marginal gravel materials employed to surface gravel roads in Iringa region. The intention was to address local characteristics influencing gravel roads deterioration in the region. To promote research on gravel roads management, the author has published seven papers and presented ten papers in established journals and conferences respectively, as indicated in the Appendix 13. It is author expectation that, given the right impetus, locally formulated gravel loss prediction models can be incorporated, as one of a tool, in gravel roads management systems (GRMS). The literature review focused on the gravel road condition surveys, modelling exercises, gravel loss, and a review of existing gravel loss prediction models. The literature review also examined the version of GRMS currently practiced in Tanzania by its road organizations. The study used factorial experimental design. Parameters which are deemed to influence the gravel loss were collected and studied. A questionnaire was used to study the status of gravel road MMS in Tanzania. The data obtained from the questionnaire responses were analysed with the aid of Statistical Package for Social Sciences (SPSS) and Microsoft Excel. A detailed gravel road condition survey of each 300 m long test section was carried out during site visits. The measurement of gravel loss through the change in average height loss formed a crucial part of the study. The modelling of a gravel loss prediction model was performed using pavemetric principles, the term coined by this study, which is principally based on econometric principles. From the analysis of questionnaire responses, it was evident that each Tanzania Roads Agency (TANROADS) regional office and district council works department needs to have a unique MMS and GRMS which reflect their operating capacity. The results of the condition survey led to the formulation of a new range of grading coefficient (GC) to suit the local marginal materials. The gravel loss survey results assisted in establishing gravel loss thresholds. The thresholds were based on the rate of gravel loss noted in the study. These thresholds can be employed to enhance the quality control of gravel roads construction and maintenance practices. The study formulated a gravel loss prediction model for Iringa region. The process utilized average daily traffic, climate, and derivatives of sieve analysis and Atterberg limits. The model is statistically significant at 1 % level. The model gives a constant gravel loss of 0.1 mm per annum regardless the state of the six variables in the model. This was attributed to autonomous loss that is the amount of gravel material lost through mechanical and chemical weathering. Recommendations include the need for gravel loss prediction models to reflect local characteristics influencing the deterioration of the gravel roads in question and the modelling capacity of local road agencies. Areas for further studies are highlighted.
The green township infrastructure design toolkit : creating eco efficient engineering solutions
(2017) Saroop, Shian Hemraj; Allopi, Dhiren
There is a growing need for co-ordination of design, sustainability, economic and environmental aspects of infrastructure projects. The provision of civil infrastructure has a major impact on the natural environment and on the quality of life. A literature review conducted highlighted that infrastructure development was focused mainly on the financial and engineering aspects of projects. There is an urgent need to apply technologies and methods that deliver better and more sustainable performance of civil infrastructure as well as a need to establish a standard of measurement for greener infrastructure. The literature review revealed that the existing tools do not adequately rate and monitor civil engineering infrastructure design decisions from concept stage, through to detailed design and implementation. The objectives of the research were to identify green design technologies that can be used in township infrastructure and to encourage sustainable design on infrastructure township services, at various stages of the project. This would require the development of a green reporting system that incorporates environmentally friendly infrastructure design solutions. This study identified alternative eco-efficient civil infrastructure design solutions and developed sustainability criteria to analyse the eco-efficiency of infrastructure projects. The study proposed a Green Township Infrastructure Design Toolkit aimed at ensuring high-performance, eco-efficient, economical and environmentally friendly design decisions on stormwater, roads, water and sanitation related to township infrastructure projects. Various case studies were undertaken on a range of infrastructure projects to ensure consistency and reliability of the toolkit. Through a series of green reports, developed for each stage of a project, the toolkit measured the environmental efficiency of the design solutions. Recommendations suggest that engineering practitioners should endeavour to integrate greener engineering solutions into the traditional method of designing of infrastructure projects. The Green Township Infrastructure Design Toolkit with the use of its green reporting tools ensures the design of sustainable township infrastructure services, by progressively ensuring efficient, affordable, economical and sustainable provision of infrastructure services.
Influence of coarse aggregate on the shear strength of reinforced concrete beams
(2020-12-17) Jajbhay, Hoosen Ahmed; Allopi, Dhiren
Research to accurately predict the shear capacity of reinforced concrete beams without shear reinforcement has been ongoing since the early 20th century. Aggregate interlock of the coarse aggregates at the shear crack interface is one of the internal mechanisms of shear transfer and a major contributor to the shear capacity of slender beams. It is plausible, therefore, to investigate if the coarse aggregate itself influences the shear capacity of a concrete beam. The influence of the type of coarse aggregate on the shear capacity of beams without shear reinforcement was investigated in this study. From the literature study an understanding of the properties of coarse aggregates was gained, the internal mechanisms of shear transfer in reinforced concrete beams without shear reinforcement were determined, and the parameters influencing shear strength were identified. Based on this information an experimental program was designed. Eighteen reinforced concrete beams without shear reinforcement were cast. The beams were cast from three different types of coarse aggregates commonly used in the Durban area, i.e., dolerite, quartzite and tillite. For each type of coarse aggregate two variations were tested, i.e., 13 mm and 19 mm maximum aggregate sizes. For each size of coarse aggregate, three concrete strengths were tested. The beams were loaded in a beam press, by applying an increasing point load offset from midspan to induce cracking on the shorter side, until shear failure of the beam occurred. For the three concrete strengths, beams cast from dolerite had the highest shear capacity while beams cast from tillite had less shear capacity than beams cast from quartzite coarse aggregate. Furthermore, beams cast from 13 mm maximum size coarse aggregate had higher shear capacity than beams cast from 19 mm aggregate. The conclusion may be drawn that the type and size of coarse aggregate does influence the shear strength of a reinforced concrete beam without shear reinforcement.
The infrastructure cost planning model : an integrated solution to cost effective design
(2009) Saroop, Shian Hemraj; Allopi, Dhiren
Infrastructure project costs are being scrutinised more closely and with greater skill and accuracy as projects have become larger, more complex and more expensive, and clients have become more exacting in their requirements. These and other factors compel engineers to design with greater care and in more detail. However, public planners spend very little time generating alternative project options, often presenting decision-makers with only a few poorly differentiated alternatives borrowed ad hoc from other projects. Even more disturbing is that they often devote the greatest amount of decision making resources to the development of a single decision rather than a variety of options. A systematic and iterative analysis of the cost consequences of different design solutions is commonly suggested for infrastructure projects, but rarely happens. There is a growing need to integrate design and costs. This study concentrates on the issue of cost optimisation of infrastructure projects (particularly at the design stage of the project) and applies construction economics, cost planning, cost optimisation and value engineering techniques to the design of such projects. The methodology proposed in this study for the optimisation of cost and design planning is the Infrastructure Cost Planning Model. This model divides the planning of a project into four stages and utilises twelve Cost Report Forms across these stages. The Cost Report Forms define in a comprehensive, precise and verifiable manner the essential characteristics of a deliverable component. They are used to measure, quantify, verify and audit the different design options. By means of the Cost Report Forms, the Infrastructure Cost Planning Model enables the client to select a combination of alternatives and evaluate a number of possible design options – with their cost implications – at each stage of the design process. This i promotes transparency and accountability, and enables consultants and clients to have greater control over the planning process and overall costs. Two case studies on infrastructure related projects were conducted and confirm that the Infrastructure Cost Planning Model can reduce costs. This study demonstrates that it is possible to overcome the problem of over expenditure by introducing cost effective design decisions prior to the infrastructure design approval process. The Infrastructure Cost Planning Model can improve infrastructure standards and procure design in a cost effective, equitable, competitive and transparent manner. This study contributes to the underdeveloped area of cost planning and forecasting of infrastructure projects. The findings are relevant to the South African government's infrastructure service delivery programme and the general issue of affordable infrastructure services.
Integrated hydrological modelling for sustainable water allocation planning : Mkomazi Basin, South Africa case study
(2018) Amoo, Taiwo Oseni; Dzwairo, Bloodless; Allopi, Dhiren
Allocation of freshwater resources between societal needs and natural ecological systems is of great concern for water managers. This development has challenged decision-makers regarding how to reasonably allocate available water resources to meet the competing demands. Thus, turning these concerns into opportunities requires the need for both water technology innovation and water behavioural change, in order to manage fresh water in a sustainable manner. This study aimed at investigating the applicability of an integrated hydrological model in a Geographical Information Systems (GIS) environment for sustainable water allocation planning and management, using the Mkomazi Basin in KwaZulu-Natal Province, South Africa, as a case study. Specifically, the study identified ecosystems that depend on Mkomazi River for preservation of their environmental and public benefit values; developed a water allocation mechanism to achieve equitable water distribution and large benefits from water uses across the basin’s users; synthesised rules for sustainable development in sharing the limited water resources and maintaining environmental quality; and finally, established a framework for water trading in order to encourage water use efficiency and allow movement of water to new users. Historical 15-year (1990-2015) observed streamflows and daily meteorological variables (precipitation sums (mm), relative humidity (%), wind speed (m s_1), mean, minimum and maximum air temperature (oC), solar radiation (MJ/m2), sunshine duration (h) and evapotranspiration (mm)) were used for this study. The hydro-meteorological data collected from various sources were subjected to frequency trend analysis, correlation, regression and the double mass curve to test their accuracy, reliability, homogeneity, consistency and localisation gaps. The ombro-thermic diagram was used to classify the months into wet and dry periods. iii The identification of prominent ecosystems that depend on the Mkomazi River was achieved through a comprehensive desktop survey and documentation acquired from the Department of Water and Sanitation (DWS). Multivariate statistical methods; cluster, factor and principal component analysis, were applied to analyse the surface water quality data sets extracted from the repository of South Africa’s water resources website (WR2012), in other assess their impact on the aquatic net benefit values and environmental preservation. A semi-distributed event process and an integrated Soil and Water Assessment Tool (SWAT) model in a GIS environment, with descriptive statistical of mean, median, mode, standard deviation, skewness, and kurtosis were employed to simulate the basin’s hydrological process in evaluating the basin’s water balance. The SWAT model was parameterised, calibrated and validated from corrected hydro-meteorological data from 2004 to 2013. Sequential Uncertainty Fitting Algorithm (SUFI2) was used for the model sensitivity analysis, calibration and validation of the model. Artificial Neural Networks (ANNs), Probability Distribution Functions (PDF), and a Flow Duration Curve (FDC) were used to project future available water. Based on the estimated available water, an estimation of allocable water was made based on percentage dependability of the river yield to the different users. The weilbul ranking was used for choosing the dependable flow; this was subsequently used for the different water riparian’s demand distribution. Large benefits derivation from water uses across the basin’s users was based on priority-driven sustainability. Extensive literature review work was used to synthesise rules for sharing limited water resources and maintaining environmental quality for sustainable development. These rules were all drawn from similar world experiences for efficient and gainful utilisation of water and other natural resources. The synthesised rules and principles were modified to suit iv KwaZulu-Natal Province (KZN) water allocation reform regulations. The established water rules were subsequently adapted to the present (Mkomazi) case study area. The proposed developed water trading framework leans on an inclusive simulation of ‘Hydrology, Environment, Life (aquatics), Policy and Sensitivity’ (HELPS) collective response of the basin in exploring the socio-economic and environmental consequences of water regulation. It uses a System Dynamic (SD) simulation technique to form a composite supply-side augmentation with demand-side improvement system to allow movement of water to new users and encourage water use efficiency. The results of the agglomerative hierarchical cluster analysis grouped the 10 sub-basin sites into three clusters of highly polluted (HP), medium polluted (MP) and relatively less polluted (LP) group basins with latent factors of 81.9, 3.14 and 0.858 (%) in the total water quality variance data sets. The water quality index analysis shows a mild effect on irrigation farming and aquatic species. The results of water balance simulation show that mean monthly values were 28.6 m3/s over the years with Nash-Sutcliffe Efficiency (NSE) values of 0.83 and a coefficient of determination (R²) of 0.77 at validation stage. The Curve Number (CN) is the most sensitive parameter for the estimation of both streamflow and water yield within the catchment. Other water balance simulation ratios include: Streamflow/precipitation (0.4 mm); Baseflow/Total flow (0.67 mm); Surface Runoff/Total flow (0.33 mm); Percolation/precipitation (0.20 mm); Deep recharge/precipitation (0.01 mm) with an Evapotranspiration/precipitation ratio of 0.58 mm respectively. The water allocation results in the different dependable flow rates of 60%, 70%, and 85% reliability revealed it to be 17465.56, 8068.04 and 6373.35 (m3/s) at U1H009 discharge station, respectively. The synthesised literature rules suggest water allocation reform acts should be catalysed v through the institutionalisation of capacity developmental platforms where climate change transformation experts and other stakeholders have input in legislating water reform acts, which should be supported by a strong political will. The invented SD framework confirms agricultural water use as the highest demand when compared with other users. Its sustainability index was evaluated as the ratio of aggregated possible water demand relative to the corresponding supply in the same period. The result shows an integrated scenario which combines rainfall variation with improved irrigation water use efficiency and gives the optimal sustainability performance index (0.25) of the system at 70% dependable flow. The simulated water balance results also reveal the use of scientific visualisation techniques in QSWAT to model spatially distributed and time-varying hydrologic-meteorological data sets in evaluating the water balance, while its calibration and validation in SWAT Calibration Uncertainty Procedure (SWAT-CUP) algorithm connotes a strong model efficiency performance. The developed SD framework provides comprehensive assessment methodology for the decision-maker in assessing water trading. The applied integrated model can be used in similar river basins sharing related attributes to the study area in resolving the current water – stressed challenges in South Africa as well as other regions of the globe. Considering the extent of the drought and the paucity of the uneven allocation of water resources at the study area, the needfulness of integrated hydrological models such as SWAT and ANNs cannot be overemphasised in ensuring the sustainability of Mkomazi Basin, while unlocking the untapped potential of water resources for the development of the agricultural and industrial sectors, and still meeting the requirements of the ecosystem.
Investigating a standardised approach towards prioritisation of gravel roads upgrade to paved roads in KwaZulu-Natal
(2023-05) Ndlovu, Gugulethu Penelope; Allopi, Dhiren
Gravel roads are natural earth roads comprising a formation/roadbed layer and an additional top layer of gravel material, referred to as the gravel wearing course (GWC). Gravel materials used for constructing the GWC layer are obtained from local quarries or borrow-pits. The performance of gravel roads is dependent on numerous factors, which include gravel wearing course materials’ suitability as well as the geological founding materials of the roadbed layer. The major challenge with gravel roads is that they are overly sensitive to weather conditions as well as to the type and volume of traffic using them. In contrast to paved roads, gravel roads deteriorate faster and require more maintenance since they are not sealed with impermeable layers. As in most countries, South Africa has a substantial proportion of gravel roads within its road network. Gravel roads are cheap to construct when compared to paved ones, however, their maintenance costs are higher than those of a paved road over time, and that poses a challenge as the allocation of road infrastructure funds is usually lower than the gravel road network needs. This results in a maintenance backlog and a rapid rate of gravel road deterioration, as well as an increase in their maintenance costs. The KwaZulu-Natal Department of Transport, hereafter being referred to as the KZN-DoT, developed a project prioritisation model for all their project categories. This research focused on investigating the methodology that the KZN-DoT implements when prioritizing for gravel roads upgrade to paved. The investigation of the KZN-DoT’s prioritisation methodology was achieved through evaluating prioritisation factors considered, traffic baseline being used when selecting gravel roads to prioritise for upgrade as well as through investigating the right time of upgrading a gravel road to paved surface. The aim of evaluating the KZN-DoT’s prioritisation model was to enhance it by further proposing its refinements where necessary. Recommendations and conclusions were drawn from the research findings for respective research questions and objectives. This research recommends the addition of some prioritisation factors into the KZN-DoT model and a gravel road performance modelling tool to be developed and used to establish each gravel road’s deterioration pattern and in turn quantify economies of retaining it as a gravel road versus paving it to determine the right time to upgrade them. This is a large study that was conducted by the researcher for the KZN-DoT. In the context of this research, the phrase, “upgrading of gravel roads” shall mean the upgrading of gravel roads to paved surface i.e., bituminous seal surfacing or asphalt. Whereas, for the KZN-DoT’s prioritisation model for gravel roads upgrading to paved shall mean upgrading of gravel roads to blacktop surface which is the term that the KZN-DoT use interchangeably with bituminous seal surfacing. In this research, where the term unpaved and unsealed road is used, it shall mean gravel road.
Investigating factors associated with insolvencies among civil engineering contractors in KwaZulu-Natal
(2016) Ntuli, Bongumusa Nhlakanipho Siphesihle; Allopi, Dhiren
Insolvency may be broadly defined as an inability of business entity to meet pending financial commitments. For a construction firm, such a situation creates conditions whereby a business entity is unable to fulfill its contractual obligations with regard to work in progress or creditors owing. There are indications to suggest that during periods of adverse conditions the occurrences of insolvencies are mutually exclusive and remain a subject of debate. The occurrence of these financial failures adversely affect business concerns operating within the civil engineering construction industry. In South Africa, figures released by the South African Federation of Civil Engineering Contractors (SAFCEC) in 1992 suggested an expected general decline in workload handled by this sector. This was a result of scaling down of heavy infrastructure projects because of government shifting focus to housing and other related projects mainly towards meeting the needs of the previously disadvantaged communities. During that period large contractors suffered financially and some went through insolvency. The government had also put emphasis on transformation of the sector to allow participation of emerging and small contractors, but this was not properly regulated, so most of these contractors did not have the experience and skills to operate sustainable construction firms. The Construction Industry Development Board (CIDB) was established in 2000 as a statutory body to provide leadership to stakeholders and to stimulate sustainable growth, reform and improvement of the construction public sector for effective delivery and the industry’s enhanced role in the country’s economy. The CIDB’s regulations were implemented after 2003 and are continuously improving the construction public sector’s growth. This research study investigated and evaluated the factors associated with insolvencies amongst civil engineering contractors in KwaZulu-Natal. The study investigated the hypotheses that “the prominent factors associated with civil engineering contractors insolvencies are related to managerial/operational issues”, the prominent factors associated with civil engineering contractors insolvencies are related to financial issues”, “South African government initiatives create an environment for small to medium contractors to develop through their implementation”, and good management and operation of small to medium construction companies reduce insolvency in construction”. Operational management and strategic factors were found to be amongst the leading causes of companies failures. The study also made some recommendations from the research findings. The findings are relevant to the South African government infrastructure service delivery programs and the general issue of affordable infrastructure services.
An investigation into the structural suitability of standard grade Expanded Polystyrene (EPS) as an innovative building material
(2019-11) Mncwango, Bonke; Allopi, Dhiren
Rapid urbanization has brought numerous economic, cultural and political development in South Africa; however, it has also led to some parts of the country turning into slums. The spread of slums is mainly driven by the lack of adequate housing provision by the Government. Although it has been twenty-five years since South Africa had its first democratic elections, millions of citizens still continue to live under squalid conditions as a result of lack of housing. The South African government cites numerous reasons for not being able to eradicate the housing backlog, including insufficient housing budget allocation as well as the worsening global economic climate. It is evident from the current housing backlogs that more building solutions that can reduce cost and construction time are needed. Further, new building materials should be explored in order to alleviate the environmental pressures that conventional building materials cause on the environment. This research investigates the properties of standard grade Expanded Polystyrene (EPS) as a potential contributor in low-cost housing provision. Currently the construction of EPS dome houses using modified EPS is only occurring outside of South Africa and it requires the possession of intricate moulding equipment. Existing suppliers require a minimum order, for instance, Japan Dome House Company supplies dome houses at a minimum order of three-hundred units. This research examines the potential of carving standard grade EPS into a form of dwelling using a hot-wire tool to re-create a model similar to a commercially produced EPS dome house. EPS components were assembled and left exposed to the elements since the main method of analyses of the live model was through exposure, particularly against rain and wind experienced within the jurisdiction of Pietermaritzburg, South Africa. Analyses of the live model was supplemented by testing of compression, flexural and thermal qualities of EPS under laboratory conditions. With wind speeds of thirty-nine km/hr and a rainfall intensity of twenty-eight mm, the model was found to still be in its original state of composure after six-months even without having been permanently anchored to the ground. Existing industry models such as Moladi, Khaya ReadyKit and Fischer Housing were examined to provide a standard of comparison for this investigation. This was done in order to distinguish how EPS dome houses differ to current existing alternative building technologies within the sector of low-cost housing. Observation of the model revealed that it is possible to successfully re-create an EPS dome house without complex moulding equipment. Some of the main findings from the laboratory analysis were that, contrary to expectations, thermo-gravimetric analyses of three different densities (fifteen kg/m3, twenty kg/m3 and thirty kg/m3) revealed that as the density of EPS increases, the maximum degradation value decreases. A study of the interaction of the polystyrene beads through microscopic analysis revealed that in higher EPS densities beads can rupture, leading to a compromise in both structural integrity and form. A water absorption test on EPS revealed that the percentage of water absorbed by EPS is similar to that absorbed by clay bricks over a 24-hour period, which makes the materials comparable in this regard. In terms of the outcomes of the study, the researcher has already published articles in three journals and two conference proceedings. This research will be of value to design professionals in alleviating the environmental impacts of commonly used conventional materials through the inclusion of EPS where low compressive loads are permissible.
Investigation on road infrastructure, traffic and safety within the Port of Durban
(2013) Kunene, Oscar M.; Allopi, Dhiren
An increase in road traffic, poor road conditions and high numbers of road accidents are major challenges at the Port of Durban. Roads are considered as the most important transport mode at the Port of Durban. Road transport has taken almost 80% of the import and export cargo while railway transport is left with approximately 20%. It is estimated that 75 million lives in the world will be lost and 750 million people injured in road accidents in the first half of the 21th century. The Port of Durban is an important vehicle for facilitating economic growth of local, regional and national industries. For the Port to maintain global competitiveness with the current trend of globalization, it has to ensure that roads are well maintained, safe and have a smooth traffic flow with no delays. This study provides an overview of the road infrastructure within the Port of Durban in relation to road condition, safety, law enforcement and traffic. Existing and ongoing studies conducted in South Africa and abroad form part of the literature review. This study identifies factors that are affecting the condition of road infrastructure such as growth of container cargo, an increase in the dimension and weight of trucks, transport deregulation, port layout and handling equipments. Deregulation of road transport over the past years has resulted in an 80:20 split between road and rail transport putting more pressure on roads. Cost and time are the major deciding factors in the freight industry. Most customers prefer to use road transport due to the lower cost and reduced time compared to rail transport. There are eight major roads within the Port that connect the South, West and North of eThekwini Municipality namely Bayhead, Quayside, Maydon, Rick Turner, Wisely, South Coast, Bluff and Iran Roads. Asset verification and assessment of the condition of the existing eight major roads found that Quayside Road is in a better condition compared to the other roads. Maydon and South Coast Roads are low rated roads which are in a poor condition. Identification and assessment of the condition of 210 000m² of asphalt paved areas which included minor roads within the Port of Durban was also conducted. Most paved areas and roads fall under D (fair) category which is reasonable but maintenance work may be required within six months. Comparison between the condition of the eight major roads within the Port and outside the Port was investigated. The findings indicate that sections of roads outside the Port are in a better condition than sections within the Port. Traffic counts were conducted in order to determine the utilization of the existing eight major roads. Bayhead and South Coast Road are highly utilized roads. Road accident reports and death reports were analyzed on these roads. Most of the road accidents take place on South Coast Road. A questionnaire survey was conducted, targeting road users who travel on these roads within the Port. Feedback was obtained on the status of road conditions, safety and traffic within the Port of Durban. Findings of this survey revealed that most of the respondents don’t know where to report road defect/s within the Port. Approximately 37.5% of the road users felt not safe to drive on roads within the Port especially on South Coast Road. A high percentage of people (93%) witnessed accidents on these roads. Traffic signals within the Port are maintained by eThekwini Municipality and are very often non-functional. When road signs need to be repaired or replaced, it takes longer than expected. Also, there are limited parking areas around the Port resulting in trucks parking closer to the premises while waiting to collect or deliver cargo. This causes major traffic congestion, for example, on Maydon Road where most trucks park on the side of the road. Recommendations include assessment guidelines that could improve road condition, safety and traffic flow. Areas to be improved with regard to road infrastructure are also highlighted.
An investigation on the impact of lime variations to the geotechnical properties of various soil samples of different Ph ranges
(2019-08) Bhengu, Phakamani Humphrey; Allopi, Dhiren
When geotechnical engineers design structures, the designs are based on the assumption that specified quality levels will be achieved for each soil layer below. This is accomplished by ensuring that each layer resists shearing and avoids excessive elastic deformations (Jawad et al., 2014). When the quality of each level of soil layer is increased, the soil's ability to distribute the load over the greater area is generally increased enough to permit the reduction in the required thickness of the soil and surface layers. Many methods can be adopted in order to achieve quality levels when trying to improve the soil strength (Azadegan, Jafari and Li, 2012). One method entails the application of lime in various concentrations to soil as a soil stabilisation process. Soil stabilisation is the alteration of soil to enhance its geotechnical properties. These properties include particle size distribution, plasticity and liquid limit, linear shrinkage, Optimum Moisture Content (OMC), Maximum Dry Density (MDD) and California Bearing Ratio (CBR) and Unconfined Compressive Strength (UCS) of the soil samples. This research examines the use of lime variations to stabilise soil in order to improve the geotechnical properties of various soil samples. The soil samples had different pH ranges due to diverse mineralogical and microstructural composition. Further, this research was inspired by the paucity of published research on the topic. Over recent years, very little research on soil stabilisation has focused on the impact of lime variations on the soil geotechnical properties towards effective soil stabilisation of soil of diverse pH ranges. To conduct the research, approximately 3900 kg of soil was collected for laboratory testing purposes. A series of laboratory tests were conducted, including consistency limits, OMC, MDD, CBR and UCS. These tests were all done in compliance with the Technical Methods for Highways Part 1 (TMH1) of South Africa, with particular emphasis on methods A1, A2, A3, A4, A7, A9 and A14 (Department of Transport, 1986a), supplemented by the pavement engineering manual by the South African National Roads Agency (SANRAL) (2013). Mineralogical tests were conducted by applying x-ray diffraction (X-RD) and scanning electron microscopy (SEM) for better understanding of the microstructure of soil samples. This was to enhance the interpretation of the physical behaviour of the soil samples. Properties partially covered in this research in a form of a literature review are as follows: texture, structure, porousness, organic matter, colour, soil-depth and soil-temperature. In terms of plasticity properties (Atterberg limits), findings of the study confirmed that many of the important engineering and mineralogical properties of soil can be enhanced by the addition of lime. The application of lime led to a reduction in plasticity of both the acidic and alkaline soil samples. The reduction mentioned above occurred due to the decrease in the thickness of the layer of the soil particles that were treated. Further, from the analysis carried out, it was found that the treatment of the soil samples with lime content increased the pH of all the samples. The changes were as a result of the changes in the chemical properties (i.e. cation exchange) and the composition of the samples due to their chemical reactions with the lime additive. This is a substantial pH increase compared to the pH of natural soil (untreated soil samples). Regarding MDD and OMC, the six soil samples displayed maximum dry densities ranging from 1500 kg/m³ to 1940 kg/m³ and optimum moisture contents ranging from 14 % to 29 %. Lime content at range of 4 % to 8 % indicated the highest density of the stabilised soil samples. The densities of the soil samples showed a slight increase at the lime content of 10 %. However, for almost all samples, the results showed that further addition of lime decreases the density and increases moisture content. Based on the results, it was discovered that the MDD is achieved at 2075 kg/m³ and at 22 % of OMC for alkaline soil sample 6 when treated with lime content of 4 %. The above implies that maximum cohesion and maximum friction are achieved at pH = 8.68. For other soil samples, the MDD decreased with increase in number of days for each of the pH conditions. This indicated that the particles of the soil samples tested were being disintegrated. This reduction in the density of the soil had an impact on the strength of the soil. Typical example for the latter is alkaline soil sample 4 of pH = 9.20, with an MDD of 1591.53 kg/m³ at 18 % of OMC. The CBR for treated soil samples compacted at 25 compactive efforts recorded lower CBR values compared to the soil samples compacted at 55 compactive efforts. Alkaline soil sample 6 of pH = 8.68 indicated constant increase in CBR for respective penetration depths of 2.54 mm, 5.08 mm and 7.62 mm. The constant increase in CBR for alkaline soil sample 6 compacted at 55 compactive efforts was a direct indication of the principal chemical reactions that took place during the lime-soil stabilisation process. In order to investigate the effect of pH on shear strength of treated soil, UCS geotechnical properties of the soil samples of different pH values (i.e. pH = 4.02, 4.92, 5.55, 9.20, 8.27 and 8.68 for sample 1 to 6 respectively) were determined using the UCS machine. Based on the results of UCS strength tests, it was found that the UCS geotechnical properties increased considerably if the soil had a high pH (pH = 8.68 for alkaline soil sample soil 6 and pH = 8.27 for alkaline soil sample 5). At an alkaline pH, the increasing of ionic strength favoured face-to-face aggregation of the soil samples. The UCS geotechnical properties decreased considerably when the pH values were less than pH = 8. This was particularly evident for acidic soil samples one of pH = 4.02, soil sample 2 of pH = 4.92 and soil sample 3 of pH = 5.55. The soil pH had no significant or direct impact on the microstructural studies of the soil tested, but the microstructural properties analysis helped ascertain which elements were found in the soil. Tests used were X-RD, SEM and energy dispersive x-ray spectroscopy (EDS/EDX). The elements found were magnesium (Mg), potassium (K), calcium (Ca), titanium (Ti), iron (Fe), aluminium (Al), silicon (Si) oxygen (O) and carbon (C). Some of the soil elements found and evaluated were significantly influenced by the usage of lime. The findings of X-RD, SEM were influenced by the source of the soil. Other contributory factors that impacted negatively the geotechnical properties of the soil tested related to the loss of the cementitious elements in both the acidic (pH < 7) and alkaline (pH > 7) soil samples. Therefore, the conclusions and recommendations include the following but are not limited to: the need for a more effective approach to reviewing designs and construction procedures for soil stabilisation; the need to achieve minimisation of carbonation to suit the intended results; and the need to take into account the pH of the soil when designing structures.
Optimizing the usage of fly ash in concrete mixes
(2017) Zulu, Sabelo N. F.; Allopi, Dhiren
Improving on our construction practices to promote sustainable development in engineering and to promote eco-friendly living is vital in the fight against global warming and associated problems. This study looked at one of the ways in which engineering can contribute to this fight through promoting the recycling of waste by-products such as fly ash (FA), on a larger scale in the cement and concrete industry, by utilizing the FA to the optimum. In this study concrete mixes of 25 MPa, 35 MPa and 50 MPa with FA partially substituting the cement at 30%, 40%, 50% and 60% were produced and numerous tests were performed to determine the optimum amount of FA that can be used and still obtain better or comparable concrete to ordinary concrete. Testing for concrete properties was conducted under laboratory conditions over a period of one year. In addition, a cost comparison between ordinary concrete and FA concrete was undertaken. The results obtained show that the increase in FA content influenced the rheological properties of fresh concrete favorable. The recorded slump increased with the increase of FA content. Increasing the FA content prolonged the setting of concrete, with the ordinary concrete taking 1 hour 45 min to set, compared to more than 2 hours for FA mixes. The FA increase had negligible effects on the air content of the concrete mixes. The drying shrinkage of concrete increased with the increase of FA content, with the strain ranging from 0,045% to 0,56%. The compressive strength results show that the control mixes with 30% FA content attained the highest compressive strength over a year. In some cases, the 40% FA strength was compatible to the 30% FA strength. The durability index results showed the control mix of 30% FA attaining better results for Oxygen Permeability Index and Sorptivity Index, with the 40% FA mix following closely. The higher FA content mixes (50% and 60%) attained better Chloride Conductivity results than the lower FA content mixes. Increasing the FA content does affect the performance of the concrete at early stages, however concrete with acceptable strength and good durability qualities can be produced even with 50% FA volume. Increasing the FA content can also significantly reduce the cost of producing and working with concrete. The practice of utilizing higher FA content in concrete can be beneficial for the South African cement and concrete industry without compromising the quality of the cement products concrete structures.