3. Electronic Theses and Dissertations (ETDs) - All submissions

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Addressing skills shortages in the South African residential construction industry through automation: a case study of Gauteng region
(2019) Takawira, Memory
The construction industry remains a cornerstone and plays a leading in many national and global economies and contributes up to 10% of GDP in developed countries and more than 25 % in developing countries. In South Africa since 2008, the industry has been contributing an average of 9% of the total employment in both formal and informal sectors and around 9% towards the GDP. Despite playing such a significant role i researches have shown that the industry is crippled with many challenges which amongst others include shortages of skilled personnel to do the work. The construction industry which oftentimes is however, over the years it has failed to deliver as per expectations owing to these skills shortages. Previous researches on construction skills shortage have focused on education and training as a remedy but this has failed to yield the desired solutions as the skills shortages are still being felt despite heavy investments in education and training. A more radical approach is thus needed to overcome these challenges. This study is therefore conducted to evaluate the potential use of robotics, automation and artificial intelligence in addressing skills shortages in the South African construction industry. In order to evaluate the potential use of automation and artificial intelligence in addressing skills shortages, there was a need to establish the records of the current skills shortage and the benefits of automation in overcoming such skills shortages. For this, meta-synthesis of existing literature was used for global skills shortages and the advantages of construction automation. To narrow down the issue of skills shortages specifically to the South African construction industry, five interviews were contacted to identify the enablers and threats for using construction automation in the country as well as the extent to which the use of such automation can affect the perceived labour intensive construction industry. Results from this study shows that, despite the construction industry playing a significant role in many economies globally, there are damning results when it comes to skills shortage. With the advent of the 4th Industrial Revolution, the use of automation and artificial intelligence in the construction industry is the next big thing. The research concluded that, although cconstruction automation and robotic technologies can be adopted and used, there should be compensation of the benefits accruing from the use of automation and artificial intelligence to offset the possibility of high levels of unemployment
An analytic hierarchy process model approach to selecting a maintenance strategy for a new nuclear power plant
(2019) Joseph, Andy Irvin
Maintenance strategies are important for the reliability and safety of nuclear power plants. Cost competitiveness in the energy markets and closure of nuclear power plants highlighted the need to optimise maintenance strategies to reduce cost while preserving safety and reliability. This research proposes using the Analytic Hierarchy Process (AHP) decision model to determine the optimal maintenance strategy mix where nuclear safety, cost and reliability are considered as the primary criteria. Nuclear experts are used to conduct pairwise comparisons to select the preferred maintenance strategy for different Continents and WANO centres. The research concludes that nuclear experts prefer safety as the highest criteria and also prefer a maintenance strategy that have a split between the preventive maintenance (PM), predictive maintenance (PdM) and reliability centered maintenance (RCM) strategies, with PM as the highest ranked maintenance strategy followed by PdM and RCM. The study also concludes that the AHP model is an effective model to be used in the nuclear industry and is comparable with results from other industries
Assessment criteria for determining the suitability of carbonate rock types for calcination in modern vertical (shaft) kilns in Southern Africa
(2019) Potgieter, E.M.
Lime kilns have been used through history, initially to produce a key building material, as demonstrated by construction in the days of the Roman empire. Since the time of the Industrial Revolution, the use of lime has developed widely into applications in chemical and metallurgical industries and environmental control. The production of good quality lime requires a high purity raw material (limestone) and well–controlled kiln operation. Lime kilns developed as shaft or vertical kilns, with rotary kilns being implemented from the early 20th century to meet the increasing demand for production of high quality lime. In recent times, new global lime kiln projects have seen the implementation of modern, high thermal efficiency vertical kilns in preference to rotary kilns due to lower heat consumption – which also contributes to a reduction in CO2 emissions – together with their ability to produce lime of competitive quality. In southern Africa, where lime has been produced mainly in rotary kilns since the mid–1950s, the most recent large–scale kiln projects have seen the installation of modern vertical kilns. Knowledge on the make-up and decomposition characteristics of the stone used for kiln feed is absolutely vital, considering that the quality of the stone directly impacts the quality of the lime product, while the behaviour of the stone under high–temperature calcination conditions can affect kiln operation. With new kiln installations, there are indications in some cases that – in spite of the established empirical tests done by kiln suppliers – kiln operating problems attributed to the feed stone characteristics have occurred unexpectedly during the commissioning and early operating stages. This research project sets out to establish a set of assessment criteria for limestone feedstocks in order to assess their suitability for use in shaft kilns. A range of analytical, visual and thermal investigative methods was used to characterise limestone, including X–ray fluorescence spectrometry (XRF) to characterise the composition, X–ray diffractometry (XRD) to characterise the major phases, Raman spectroscopy to characterise the minor phases, single particle analysis to characterise impurities/phases, petrography to characterise the geological make-up, decrepitation tests and thermogravimetry to characterise the decomposition behaviour. These techniques were applied to three limestones and one dolomite, all of high grade (purity), from three different geographic regions in southern Africa. Each carbonate rock had a unique chemical composition and geological origin. The complexity of each sample’s unique chemical and physical features necessitated a thorough review of each rock’s geological history. The review gave a better understanding of the phases and crystal structure in the stone that was formed during sedimentation. This investigation found that the assessment criteria of limestone had to include physical and chemical characterisation methods with an emphasis on physical characterisation. The thermal methods and petrography were used to assess the physical characteristics such as crystal size and decomposition behaviour; while the chemical methods were used to assess the chemical characteristics such as chemical and phase composition. The two types of method were applied in a complementary approach. Thermal methods together with petrography were found to be the most adequate methods for assessing the suitability of stone for use in shaft kilns. Petrography offered information on how the hot gasses move through the crystal structure during calcination and the thermal methods showed how the decomposition was affected by that movement of hot gasses. However, analytical techniques were complementary to the thermal techniques, offering explanations for observations in the thermal methods.
Assessment of risks associated with implementation of buildings information modelling in maintenance of commercial buildings in Gauteng
(2019) Mutingwende, Ernest
The greatest wealth of the world is made up of real estate, which is estimated at more than 50% of total global worth. Research has shown that the cost of maintaining real estate is greater when compared to the cost of development in the long run. Building Information Modelling (BIM) is regarded as an approach of minimising huge maintenance costs. As such, countries including UK, UAE, Canada, New Zealand, Australia and USA have introduced BIM in their building and construction projects. In South Africa, despite advocacy by the BIM Institute and other construction industry players, BIM adoption is still behind the global trend. This research applies the risk management process for those risks related with the implementation of BIM in maintenance of commercial buildings in Gauteng, South Africa. The mixed research method is used in this study through archival research, survey strategy and case study approach. Qualitative data analysis through descriptive and pattern coding is done using NVivo software, while quantitative data analysis is done using the risk matrix analysis tool. The results show that the major risk categories for BIM implementation in maintenance of commercial buildings are Technical, Financial or Economic, Legal and Management related. A total of fifteen risks from all the categories were identified to be the riskiest and recommendations on the best response measures were made. The conclusion is that asset managers do not realize the benefit of BIM largely due to lack of BIM education, wrong and misleading information and the fear of the unknown. Subsequently, there is a need to follow in the footsteps of property industries such as the Irish industry that recognized this shortfall very early and led BIM leaders to focus on targeting the building owners and facilities managers and or asset managers to be better informed and correctly educated
Beneficiary participation in enhanced people's housing process (EPHP) projects in rural communities of Chris Hani district, Eastern Cape province
(2019) Njikelana, Phaphama Helena
Community participation is one of the sustainable human settlement’s focuses, intended to guarantee that communities are an integral part that determines the design, implementation and out of the programmes in relation to their developmental needs. Community participation empowers the community members through skills development and capabilities which enables them to negotiate and make appropriate decisions for their development. In South Africa, Enhanced People’s Housing Process (EPHP) is one policy that enforces this. However community participation especially in project implementation is not without challenges. The research was aimed at assessing the extent of beneficiary participation in Enhanced People Housing Process (EPHP) in rural Eastern Cape. The study focused on the case study of Zwart Water and Lubisi Villages in the Chris Hani District, where the EPHP (the forerunner of the EPHP) programme is being implemented. The research drew from literature on the development of EPHP in South Africa, self-help housing and community driven development. A qualitative research method was adopted and both primary and secondary data collection techniques were adopted. The study revealed that despite policy assertion putting beneficiaries as drivers of the EPHP, the actual implementation of EPHP clearly shows a disjuncture between policy interface and actual implementation. The majority of the beneficiaries did not have a full control of their projects and have decision making in the initiation, planning and implementation stages of their houses constructions. The study further revealed that the EPHP in both villages is externally driven, top down managed and private contractors/developers driven against the people driven approach as stipulated by the EPHP policy guidelines. The main finding is that beneficiaries only participated as general labourers for a wage during their actual housing construction and were not directly involved in decision making concerning the building plans and other EPHP process. It is therefore recommended that all level of government should ensure strong commitment to community participation in programme implementation as stipulated by the policy
Boulder placement for aquatic habitats
(2019) Heyneke, Maria
The use of boulders simulates naturally occurring river habitats and has been acknowledged as a tool to reintroduce habitats into channelised river systems. This investigation aimed to provide guidance for increasing and quantifying suitable habitat heterogeneity for aquatic biodiversity. Boulders create hydraulic diversity by altering the velocity and flow depth of water in the immediate surroundings, of which the change in flow depth is small and localised around the boulder edge while changes in velocity can extend from several to hundreds of metres. Boulders placed in a channel reduce the velocity upstream and downstream of the object and increase the velocity on the sides. The upstream and downstream regions showed much larger areas of disturbed flow when compared to the sides of the boulder. Low percentage variations from uniform flow also occupied the greatest disturbed region areas. Experimental velocities were compared to the results of a two-dimensional hydrodynamic finite element software, namely Argus ONE and RiverFLO-2D. The software was found to neglect the turbulent wakes downstream of boulders and correction factors were developed to calibrate software output. The fundamental variables which affect the size of any velocity distribution were identified; these consisted of hydraulic (Froude number) and geometric variables (channel width and boulder diameter). Using these variables empirical relationships were developed to determine the distance from the boulder where a certain velocity percentage variation from uniform velocity was experienced in the upstream, downstream and side directions respectively. The geometric variables were found to be the dominant variables and practical approximations were also developed to determine the velocity changes using only the channel geometry. The investigation of one boulder revealed that a limiting boulder diameter exists above which blockage of the channel will occur. Following the identification of the blockage ratio limit it was found that below the limit the downstream velocity disturbance is the largest and above the limit the upstream velocity increases to such an extent that flow conditions are changed hundreds of metres upstream. Two boulders placed on the same axis perpendicular to the direction of flow showed that the disturbed velocity area increased as they were moved closer to each other. A relationship to determine the optimum spacing between boulders was developed. The resultant velocity change caused by two boulders at the optimum spacing was found to be equivalent to one boulder with double the volume. Again, empirical relationships were developed to determine the distance from the boulder where a certain velocity percentage variation from uniform velocity was experienced
Challenges to the implementation of environmental management plans (EMPs) in construction projects
(2019) Nyamazana, Primrose Tariro
A conjoint analysis of Johannesburg office tenants' preferences, South Africa
(2019) Siamuzyulu, Moono Arnold
Purpose – This study established the factors that influence office relocation decisions in the Johannesburg metropolitan area. The study aimed to obtain rank ordering (importance) of nine (9) selected factors that can be used to guide relocation and other investment decisions within the metropole. Design/Methodology/Approach – Literature review of a plethora of studies was used as the basis for this study. A questionnaire used by (Weaver, 1985) in the USA to conduct a conjoint study in the real estate sector was adapted to suit the South African context. Additional variables and levels were added, to better reflect the context of the study. Data was collected from office users in P‐grade, A‐grade and B‐grade properties whilst a conjoint methodology was used to analyse the data. Findings – The results showed that the most important factor influencing tenants’ preferences was parking followed by Landlord reputation; Size of the building was third in importance with Security as fourth and Green Rating fifth. Accessibility of the building was sixth; Location of the building, seventh with the rental cost (total cost of occupation) and the grade of the building being the bottom two factors in eighth and ninth places respectively. These results reinstate earlier findings in the South African market albeit the differences in the factor importance. Research Limitations/Implications – The study looked at nine (9) variables each with three (3) levels. The increased number of variables and levels added to the complexity of the user profiles. In addition, the sample only included office tenants in P‐grade, A‐grade and B‐grade office buildings in the greater Johannesburg metropolis. Current literature shows that newer “preference” procedures like stated preference elicitation reveal deeper and broader information on customer preferences than that obtained using choice‐based conjoint analysis. Originality/Value – The research makes scholarship and practice contributions to the fields of property management, tenant acquisition, and tenant management specifically illustrating the application of market research techniques to the office market in an emerging economy, which is not a common area of scientific interest mainly due to unavailability of data inter alia. The use of conjoint analysis in the determination of preferences for would‐be tenants in the South African office market will go a long way in reducing financial losses attributable to low occupancy levels and high tenant churn.
Economic viability of K04 open pit mineral resource to ameliorate production hiatus in 2019 and 2022
(2019) Mushongahande, Emmanuel
Venetia Mine is the largest diamond mine for the De Beers Group of Companies (DBGC) in South Africa contributing approximately 80% of revenue for the company. The Venetia Kimberlite Cluster (VKC) comprises of 13 pipes and one dyke, of these K01, K02, and K03 are mined productively while the satellite bodies that are intersected during waste stripping and push backs are stockpiled separately. The current open pit operation will come to an end in 2022, whereupon the K01 and K02 ore bodies will be mined from underground. Shaft sinking and development of underground infrastructure is underway, and it is envisaged that the change over from open pit to underground will be effected in 2022. There are two challenges facing the company that may result in a production hiatus in 2019 and 2022. The first challenge relates to failure to open kimberlite ore in the Cut4 south push back by 2019 and the second one is failure to seamlessly change from open pit to underground in 2022 when the open pit reaches its Life of Mine (LoM). The backlog of waste stripping in the Cut4 south and technical challenges faced in the implementation and execution of the Canadian Shaft Sinking method at Venetia Mine have both pointed to periods where there will be less ore mined thus resulting in less carats recovered. In order to cushion for these scenarios, the economic viability of K04 satellite pipe was investigated by conducting a Whittle optimum pit selection of the pipe to mine the ore. This was previously excluded by the current pit design. The strategy for K04 optimum pit selection was based on net present value (NPV), revenue factors, stripping ratios, and the life of the mine. This strategy was employed when analysing 13 pits from scenario 2. The selection process identified pit 9 as an optimum pit. It must be noted that this pit inventory does not add significant numbers of carats to the overall carat profile to lift the valley of despair in 2019 and 2022 but will contribute some NPV of ZAR13.2 million over a period of 6 years. K04 project will contribute 402 thousand carats against 1.5 million carats required to fill the hiatus gap, hence does not support a sound business case for Venetia Mine. It is therefore recommended that DBCM deploy a different strategy to reduce the impact of the carat shortfall in 2019 and 2022. Some recommendations include reducing mining activities in the north of the pit and focus more on accelerating waste stripping in the south in order to expose ore sooner. Cost saving initiatives such as reducing operating costs and postponing some capital projects that are deemed not urgent will go a long way in the reducing the financial impact in 2019 and 2022.
The effect of a lack of knowledge and experience on the part of the project manager affecting the critical success factors within the project life cycle phases
(2019) Visser, Hercules
After being a project manager for many years and overseeing projects in South Africa and beyond the researcher began to ask questions about the reasons for so many project failures. The researcher was motivated to investigate the effect of project managers’ lack of knowledge and experience on the critical success factors within the project life cycle phases. The main objective of this study was to identify the most critical success factors in a project and discover why the implementation of these factors ensures the successful delivery of a project. This research was intended for the engineers who wish to enter the office of the project manager. A comprehensive literature review on project management principles laid the foundation for the research methodology. The researcher formulated a pilot questionnaire which was reviewed by a panel of experienced engineers. The questionnaire was based on the five-point Likert scale instrument, designed to address both quantitative and qualitative applications with minor changes (ranking versus rating method). The software used for analysing the quantitative questionnaires was the IBM SPSS Statistics 24 and the software for data capturing was the MySQL. Using quantitative as well as qualitative research and integrating the two research methods exposed the shortcomings in project management practice
The effect of various particle size fractions of fly ash additions on the properties and performance of oil well cements
(2019) Rongai, Gladmore
Fly ash as supplementary cementitious materials had reduced the total price of Portland cement and has reduced the greenhouse gas emissions resulting in a sustainable “green” concrete. This study investigates the effect of various particle size fractions of fly ash as additive to cement in various amount on the properties and performance of oil well cements. An investigation on the effects of the different particle size and the various compositions was made. The fly ash were separated using sieves laid on top of the other and were allowed to vibrate allowing sieving of the fly ash. Various sieve sizes were used including 25um, 38um, 45um, 53um, 68um, 75um as well as 90um respectively. The retained fly ashes within the sieves were tested for performance when mixed at 0.35 water to cement ratio. The fly ash - cement slurries were tested for their shear stress and rate, compression strength, as well as water loss for a specific particle size and in different compositions. Graphs were plotted to show the different performance of cement slurries at different particle size composition against shear rate and shear stress. Experiments were carried out to determine the performance of the different particle size composition on the compressive strength and water loss. AAS was also used to determine the chemical composition of the fly ash and cement. Higher and low compression strength were observed for 38um and 75um particle size of the fly ash, respectively. Low fly ash content (10%) showed better strength compared to 40 %. Rheology test showed that fly ash - cement slurries followed the Bingham plastic model. An increase in fly ash content (from 10% to 70%) decreases the apparent viscosity from 596.59 and 394.17Pa. Results also showed that higher content fly ash lowered the yield stress of cement mixture. Finally, highest rate of water loss was recorded for low fly ash content (10 %)
The effects of cut-off grade and block sizes on the net present value for an iron ore deposit
(2019) Malisa, Moore Theresa
Optimisation of the Net Present Value (NPV) needs to consider cut-off grade as well as the block model size. This study considered the impact of these on the optimisation of the NPV. The orebody could be mined sub-optimally due to the misunderstanding of the relationship between cut-off grade and block model size. The research was based on an iron ore deposit mined through open-pit mining method in South Africa. The main objectives of the study were: to understand the importance of cut-off grade; to determine the effect of block model sizes on the average grade; to determine the effects of the block sizes and cut-off grades on the NPV, and to determine which block sizes and cut-off grade maximise the NPV. It was found that there were different cut-off grades at different levels of the exploitation of the iron ore deposit. These differences can lead to the deposit not being mined optimally. Therefore, it was important to understand the importance of cut-off grades, hence the need to investigate the effects of cut-off grades. The effect of block sizes on the NPV was included because there was insufficient research on the topic. From the literature review, the cut-off grade was defined as the boundary that separates material that is discarded from the material that is taken further for treatment. The cut-off grade determines whether the material will be considered as waste or ore. If the cut-off grade is too high, more material will be discarded as waste while a lower cut-off grade increases the entire mining capacity. The lower the cut-off grade, the higher the Mineral Reserve. It was shown from the literature that the determination of the cut-off grade is determined by factors such as the price of the commodity, production costs, grade distribution, environmental factors and other factors. The literature review highlighted that a block model is a representation of orebody characteristics, whereby a single cube will have sizes (x, y and z). The single cube will be allocated with grades, volumes, rock types, densities and many more attributes assigned to it depending on what information is required. The block model dimensions should represent the minimum block that could be selectively mined, that is, the smallest selective mining unit. The block model sizes are selected at the initial stages of creating the block model. The block size is also dependent on the sample spacing. The block size should be one-half or one-fourth of the sample spacing. When the selective mining unit is selected it should take into account the excavator that will be used to load the material. The selective mining unit is important since it determines the amount of dilution that will be encountered during mining. The larger the selective mining unit, the more the dilution, which decreases the grades. The methodology that was used to analyse the effects of cut-off grade and block sizes on the NPV was through the use of grade-tonnage curves and the DCF for different block sizes and cut-off grades. NPV is the sum of the DCF’s and the NPV assists in projecting the future revenues in terms of mines that are already in production. The DCF’s for this report were done only for 10 years because it was enough to create data of a high level of confidence. The cut-off grades that were used were 53%,60%,63% and 64% Fe as they covered the definition of the ore for the iron ore deposit. The base block model size 6.25m x 6.25m x10m.The base block-model was re-blocked into sizes: 12.5m x 12.5m x 10m; 25m x 25m x 10m and 50m x 50m x10m. Grade-tonnage curves were created for each block model size including the base 6.25m x 6.25m x 10m block model. The obtained tonnes and an average grade above certain cut-off grade were used to create the DCF in Excel to obtain the NPV. The results showed that an increase in the cut-off grade decreases the tonnes above the cut-off grade while increasing the average grade. The larger the block size, the lower the average grade due to increased dilution. The larger block sizes result in a lower NPV if the effects of mining selectively are not considered. However, if the effects of selective mining are considered, larger block sizes result in an optimised NPV. Some of the conclusions were that small block sizes result in an optimised NPV only if the effects of selective mining are not considered while larger block sizes result in an optimised NPV when the effects of selective mining are considered. The 25m x 25m x 10m which is a larger block model size is not affected by selective mining and it resulted in a higher NPV when compared to the 12.5m x 12.5m x 10m,therefore,it is better to work with larger block model sizes to avoid selective mining. It was recommended that a 60% Fe cut-off grade paired with a 12.5m x 12.5m x 10m block size to be used when the effects of selective mining are not considered since it increases the tonnes above the cut-off grade, thus increasing the LOM and the NPV is optimised. A 60% Fe cut-off grade paired with a 12.5m x 12.5m x 10m block size was also recommended to be used when the effects of selective mining are considered as this optimises the NPV. A 60% Fe cut-off grade paired with a 25m x 25m x 10m block size is recommended since it does not require to be mined selectively.
Effects of mixed income housing on neighourhood house prices and investment guidelines for future inclusive developments in South Africa
(2019) Simbanegavi, Prisca
While Mixed Income Housing (MIH) enables inclusivity in the globalized world, opposition known as NIMBY (‘Not In My Back Yard’) seem to counter such change in land-use as it is purported to increase home ownership ‘risks’ for reasons associated with loss of value to property, increased crime, and overcrowding on services and amenities. The courts delay the approval processes for such change in land-use, which becomes cumbersome and risky for investors and reduces the much needed investment funds into housing. The study provides five key direct investment guidelines to reduce the high NIMBY opposition levels in future MIH developments, which are perhaps not entirely justified, given the ‘minimal’ effect (0.41%) found for Cosmo City MIH. The first guideline is that policy development into law is not necessary, as linking bulk infrastructure and land cost to affordable housing units acts as a negotiation tool sufficient to enforce reasonable amounts of low-income housing units into MIH developments. The second guideline is that, a privately oriented collaboration between government and private sector enables MIH developments to attract the much needed funding towards housing. This enables the private sector to build better quality housing that maintains investment value in the future and yields a financial return required in the private investment performance benchmarks. The third guideline is that self-serving developments with well-developed infrastructure, transport linkages, and social amenities on greenfield sites, enable long-term focus on investment returns, value capture, continuity, and sustainability within residential markets. The fourth investment guideline is that an MIH development should focus on mixing households according to income levels through different typologies rather than race, religion or culture in the form of ‘silo’ mixing. The fifth investment guideline requires asset and property management strategy orientation to the private sector as this enables competitive resource allocation, green building technology, and better revenue collection methods as a basis for successful future MIH developments
Evaluation the knowledge and implementation of waste management by contractors in Gauteng province
(2019) Maneli, Siyawakha
While much has been written about the barriers to sustainable construction globally and particularly in South Africa, the implementation of the concept is still a challenge. The aim of this research is to investigate the awareness and understanding towards environmental aspects specifically on-site Construction Waste management (Handling of waste, use of prefabrication and reuse of waste) as sustainable practise amongst construction contractors in South Africa. These barriers have limited adaptability within the industry and hence depriving the industries of the expected benefits associated with sustainable construction practices. This research focuses on the knowledge, implementation and the impact of construction waste management and the use of prefabrication as sustainable construction practices in South African buildings projects, Gauteng. A questionnaire on construction waste management was directed to experienced professionals, on recently completed building projects and on-going building projects. Previous results shown that construction waste management by reduction, re-use and recycle is one of the major benefits of using prefabrication compared with conventional construction. In this study it was observed that South Africa contractors, particularly in the Gauteng province, fail to adopt basics of sustainable construction practices in construction of buildings projects. Observed also was the eight (8) most common barriers to the construction of sustainable buildings are Knowledge and Implementation, Prefabrication as a substantial componentry, Waste management as a sustainable construction practice reduces cost, Precast as sustainable construction practice at design stages, Materials recycle and re-use on your projects as sustainable construction practice. Others are; the effect of cost of sustainable materials compared to normal construction, environmental management, exposure to experts in one’s profession and the commitment of construction firm/ organisation. Also noticed was that some contractors mentioned government involvement or funding into the practice of sustainable construction practices. In conclusion, the research demonstrates that much needs to be done in Gauteng province with regards to waste management and sustainable construction practise be it by the government through funding and schools including professionals working in the industry.
Expansion fan/shock wave interactions between bodies in close proximity
(2019) Nel, Lara Joy
Fabrication of erosion resistant WC-Ni based coatings using cold gas dynamic spaying
(2019) Lioma, Dineo Boitumelo Thansanqa
This paper provides a review on cold gas dynamic spraying (CGDS) and its application to produce WC-based wear resistant coatings. CGDS is a deposition technique, in which fine, solid powder particulates are accelerated to supersonic speeds by means of a pressurized carrier gas. The high velocity particles are impacted onto a surface to form dense coatings. Severe plastic deformation of the particles during deposition is required to achieve sufficient adhesion and coating build-up. This process involves limited to no melting during coating deposition, thus, the chemical composition and bulk properties of the coatings typically remain identical to the feedstock powders. Substrate and particle adhesion occur as a result of highly localized adiabatic shearing, and the formation of a material jet of the ductile material, allowing for material interlocking and mechanical bonding. Deposition of WC-based coatings has been achieved using high pressure CGDS systems, with dense coatings having thickness and hardness values comparable to HVOF coatings. It is generally challenging to achieve the adhesion of WC-based coatings using low pressure CGDS systems; the addition of a ductile binder metal such as Cu, Ni and Al in the form of a MMC is generally required to facilitate deposition. Limited studies have been done on the wear resistance of cold sprayed WC-based coatings. To date it has been shown that WC-based coatings deposited using both high and low CGDS systems, possess higher sliding and abrasive wear resistances compared to coatings deposited using some HVOF techniques. The typical wear mechanisms observed are plastic deformation of the ductile metal matrix with minimal damage of the hard WC grains. Changes in wear mechanisms during wear have also been noted and appear to be influenced by the amount of WC present
Feasibility assessment of projects for risk of failure: how feasibility assessment are done for infrastructure projects
(2019) Smith, Ronald George
Avoiding project failure is a concern within the discipline of project planning and management. Feasibility assessment is a front-end process used in project planning to analyse risks and avoid failure. The aim was to explore how feasibility assessments for large infrastructure development projects are conducted and the extent to which risk of failure is recognised. Literature review established theory and definition of feasibility assessment as applied to projects. Two cases of large scale infrastructure development projects in South Africa were investigated to compare different approaches of how feasibility assessments are conducted. Methodology was a combination of direct observation, interviews and analysis of documents collected from the case studies. The predominant risk factor recognised by expert feasibility assessors in both cases was found to be perception of risk itself. Questions asked of the experts are designed to lead to a confirmation that the project could go ahead. The questions do not necessarily ask opinion on whether the project should go ahead. Comparison of the cases showed that the process of feasibility assessment was driven by each assessing firm’s own interpretation of the purpose and objective of feasibility assessment. Overall, the study confirms that the feasibility assessment process is useful as a way for project managers to recognise risk of failure before deciding to proceed with a project. However, the process depends on each assessor’s own interpretation of the definition of feasibility assessment and its purpose. Further research is suggested into the distinction between the reasons justifying why a feasibility assessment was not done, and the reasons why feasibility assessment was not considered for a project
Gas atomized versus water atomized nickel powder for the development of WC-Ni cold spray wear resistant coatings
(2019) Chingosho, Tatenda
A research study was done to compare cold sprayed cermet coatings produced from two nickel (Ni) powders manufactured by the gas atomization and water atomization processes respectively. The aim of the research was to investigate if the Ni powders could be used to fabricate cold sprayed cermet coatings having good slurry abrasion resistance properties. The Ni powder was blended with tungsten carbide (WC) powder and deposited onto mild steel substrates using a low pressure cold spray machine to produce WC-5wt%Ni coatings. A Design of Experiments matrix was used to determine the near-optimal deposition parameters. The resulting coatings were relatively thin which exhibited mostly rebounding of feedstock powder rather than deposition. An annealing stage was introduced so as to make the Nickel powders more favourable for deposition on the mild steel substrate. The annealing caused softening of the Ni powder which led to better deformation properties upon impingement with the mild steel surface. Several materials characterization tests were conducted on the coatings to determine the microstructural and mechanical properties. Three body slurry abrasion tests were done to investigate the wear properties. Both Ni powders produced WC-5wt%Ni coatings without new phases, decarburization or oxidation. The coatings based on the annealed gas atomized Ni powder showed improved deposition, better adherence to the substrate, thicker and dense coatings whereas the coatings based on the annealed water atomized Ni powder showed little deposition improvement, the powder particles bounced off the substrate more than they adhered to the substrate. The coatings based on the annealed gas atomized Ni powder had a thickness of 255 ± 33.5 μm, a hardness of 361 ± 38 HV0.3, WC retention of 42.9 ± 0.7 % and a percentage porosity of 0.7 ± 0.3 % whereas the coatings based on the annealed water atomized Ni powder had a thickness of 28.5 ± 1.1 μm, a hardness of 426 ± 12 HV0.3, WC retention of 49.5 ± 2.5 % and a percentage porosity of 1.3 ± 0.8 %. The gas atomized Ni powder provided coatings with the best slurry abrasion properties.
Implementation of mechanized roof-bolters for low-seam hard-rock mining
(2019) Kempenaars, Cornelius
As commodity prices decrease and health and safety requirements increase, it is of the utmost importance to understand the complexity of converting the existing conventional mines to mechanized mining operations. This is necessary for the mining industry in order to remain competitive, as there are minimal numbers of new mining ventures taking place. There have been many previous attempts to do this type of conversion in the mining industry that have not been successful and also not well-documented, thus the knowledge is lost to the industry. The intention of this case study is to understand the process followed by a specific mine in converting from a conventional roof-bolt installation to a mechanized roof-bolt installation method in an already semi-mechanized operation. The objective of many mines is to improve the health and safety of the employees who are exposed to dangerous areas, as well as to improve productivity and efficiency to ensure a more competitive position in the market. That objective also applies to this case study. By evaluating this project through a process of interviews with role-players, based on knowledge gained from the industry and aspects that were seen as important in various other literature studies, it was possible to determine what worked, what did not work and what lessons were learned during this project that could be valuable to the industry. Through this process it can be determined which of these aspects impacted on the implementation of this type of conversion project. It is also clear that each conversion project will have its own dynamics but there will be the basic elements such as the types of equipment, human factors and management processes that will apply to most mechanization projects. The biggest driver for the success of mechanization in the mining industry will be with regard to how to ensure job security while introducing mechanization, which does not apply only to the mine itself but to both the mining and manufacturing industries. Dwarsrivier Mine overcame this big hurdle by making a profoundly bold decision, namely that no one would lose his job. In essence, this ensured a more candid approach to making this implementation process a success. The improvements that the new equipment brings must be understood, as well as what the consequences will be in other sections or departments of the organisation. Setting realistic targets for the short and long term will be valuable, and allowing time for the operators to mature will give the highest return on investment in the implemented equipment.
Implementing gap market housing programme in a community characterized by informal settlements: a case study of Alexandra urban renewal project in Johannesburg, South Africa
(2019) Musetha, Mboniseni Aubrey
In post-apartheid South Africa, the government made tremendous efforts to ensure poor people’s access to housing. Many houses were delivered under the capital subsidy process which targeted mainly those earning an income value of between R0-R3 501. These are houses build as part of a government-funded social housing project. However, this created a ‘gap’ in the market between those who earned below the threshold of R3 500 a month, and those who earned enough to get a mortgage. The government therefore created funding instruments to support these kinds of households. In 2012, it created the Finance Linked Individual Subsidy Programme which worked by on the basis of giving assistance to households that qualify for mortgage to buy a house or open stand which is serviced but linked to a contractor. Those who qualify for this scheme are regarded to be occupying the gap market. They are those who are not eligible for the full subsidised scheme while at the same time they do not for a housing loan from the banks. Their salary earning range from R3 501 and R15 000 per month. Alexandra is a major township with a population of 179,624 people. In February 2001, the government launched the Alexandra Renewal programme which was aimed at conducting a sustainable campaign programme to deal with urban and rural poverty. This campaign also included dealing with underdevelopment, and all sectors and resources from government were to be coordinated towards meeting this goal. Its objectives included to eradicate poverty, equity, underdevelopment, enhance the capacity of local government to deliver and enhance social cohesion. As part of this programme a large number of fully subsidised houses have been built and are still planned. In addition, a set of blocks with 232 FLISP units were planned and construction began in 2013. Applications were received of more than 5000 and housing was assigned to those able to secure the correct finance, meaning that a screening and verification process was conducted to reduce the number of applicants to less than 500. However, this housing was heavily contested by those whose applications were turned down and; other political and civic organisations as they were not content with the screening and allocation process. In expressing their discontent with this project, they went as far as destroying windows, roofs, gutter and doors of these houses. They also occupied units in one of the sites of the FLIP project. In this research project, I conducted interviews with beneficiaries, those who did not qualify, government officials and other stakeholders in order to determine the contestations surrounding the FLISP project in Alexandra. This overriding aim was guided by sub research question which were aimed at understanding the policy frameworks that are in place to promote mixed housing projects, the reasons behind the adoption of gap market housing project in Alexandra, the experience of beneficiaries of gap market housing project since they moved to their units, the reasons for contestations surrounding the gap market initiative in Alexandra, and the measures have authorities taken to manage and resolve these contestations. This research showed that while FLISP came in place as one way of fast tracking the delivery of housing units in South Africa by providing affordable housing to a segment that was considered “too rich” to receive a free subsidy house from the government, yet “too poor” to access the normal housing loans stream from banks/financial institutions (DHS, 2014), the servicing of this Gap market seems to be slow. In Alexandra, when the “GAP Market” initiative was launched in 2013, it was expected to be completed in 2015 but this did not happen. This is the source of many contestation that has led to invasions of units under FLIP project. There is need to fast track the construction and allocation process in such projects. The department of human settlement and other stakeholders should embark on a program of educating borrowers to improve their financial knowledge. This might help applicant or beneficiaries to prioritise their housing needs and manage debts.

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