Stakeholders’ Perception and Adoption of Upcycling for Material Utilisation Plans in Road Construction: The Case of South Africa

Abstract

Transportation infrastructure underpins national mobility and economic growth, yet material sourcing for road construction imposes significant environmental and financial costs. As South Africa advances towards road construction, upcycling the reuse of reclaimed materials in higher-value applications offers opportunities to reduce waste and improve circular resource efficiency. This study assesses stakeholders’ perception and adoption of upcycling in the Material Utilisation Plans (MUPs) for road construction. A mixed-methods approach combined nine semi-structured interviews and thirty-two survey responses from professionals involved in the National Route 3 upgrade project. Thematic analysis identified key qualitative themes, while quantituative data from a five-point Likert scale were examined through descriptive statistics, reliability, and correlation analysis. Respondents supported existing downcycling practices (mean = 3.682, SD = 1.088) and expressed readiness to adopt upcycling for pavement surfacing, base, subbase, and subgrade (mean > 3.00, SD < 1.30). Major barriers included client specifications, limited awareness and material cost constraints. Reliability analysis (Cronbach’s α = 0.64–0.88) confirmed internal consistency across qualitative themes. Also, there was a positive correlation between reclaimed materials and cost, design specifications, and optimised cost (r > 0.30, p < 0.05), while downcycling correlated negatively with costs (r = −0.400, p < 0.05). This study provides new empirical evidence on the systemic barriers hindering upcycling adoption in South African road projects and offers a validated mixed-method framework linking perceptual, technical, and economic dimensions of material reuse. It recommends integrating upcycling criteria into design, testing, and procurement processes, shifting from compliance-based recycling to performance-based circular material management in national road infrastructure.

1. Introduction

1.1. Background

Globally, the road construction sector is adopting circular economy strategies to enhance material efficiency, reduce costs, and mitigate environmental degradation [1,2,3]. Rapid urbanisation has intensified the demand for aggregates and bitumen while generating substantial waste [4]. Upcycling is the transformation of reclaimed materials into products of higher functional value, which offers a sustainable pathway for road construction, improving durability and cost-effectiveness compared with conventional recycling that typically downgrades material properties [2,5,6].

In South Africa, the uptake of upcycling remains limited due to inconsistent project planning, inadequate specification frameworks, and procurement systems that prioritise lowest-cost tendering over innovation [7,8,9]. The absence of explicit upcycling requirements in contract documents discourages contractors from innovation for fear of cost and risk penalties [7]. As a result, economic and environmental benefits are lost, despite evidence that well-processed reclaimed base and subbase materials can adequately substitute natural aggregates while maintaining efficient performance properties [4,10,11]. Embedding upcycling into project design could therefore lower emissions, conserve resources, and support long-term sustainability goals [12,13].

Another challenge is the limited awareness and technical expertise among designers, contractors, and decision-makers [9]. This knowledge gap extends to tertiary education, where upcycling concepts are rarely incorporated into pavement-engineering curricula. Without targeted capacity building, emerging professionals struggle to translate circular economy principles into practical design and construction choices [6,14].

Empirical evidence indicates that although awareness of recycling technologies is improving rapidly in recent times, the integration of upcycling within Materials Utilisation Plans (MUPs) is hindered by additional challenges, such as the lack of coordinated planning and risk-averse tendering processes [9,11,15,16,17]. Furthermore, international studies have highlighted the potential of recycled materials to achieve cost savings, lower greenhouse-gas emissions, and maintain structural integrity [4,11,13,18], underscoring the importance of systemic change within the infrastructure development system. No integrated study has recently linked design specifications, client requirements, and cost considerations to the practical implementation of upcycling within MUPs. This has left a major knowledge and practice gap between the technical feasibility demonstrated in the limited adoption observed in real-world projects.

Addressing this gap is therefore crucial to understanding how institutional culture, design frameworks, and procurement mechanisms influence the feasibility of upcycling within South African road construction projects.

Accordingly, this study investigates the institutional, technical, and economic factors influencing stakeholders’ perceptions of upcycling within MUPs for road construction. By combining qualitative insights and quantitative validation, it develops an evidence-based framework for integrating upcycling principles into sustainable material management practices in South Africa’s road sector.

The aim of this research is to examine stakeholders’ perceptions and the factors influencing the adoption of upcycling practices in MUP design, as well as their implications for sustainable road infrastructure development. The research questions guiding this study are as follows:

• What is the perception of South African experts in the road construction industry regarding upcycling in MUPs?
• What are the factors influencing the specifications of upcycling in the design of MUPs in South Africa?
• To what extent do the identified factors influence the specifications of upcycling in the design of MUPs in South Africa?

1.2. Theoretical Framework

Material optimisation in road construction requires the strategic integration of resource efficiency, cost management, and sustainability considerations across project life cycles [15,16]. The reuse of reclaimed materials from recycling—downcycling or upcycling has been demonstrated to reduce demand for natural resources, lower energy consumption, and decrease greenhouse-gas emissions [11,17]. The circular economy paradigm underpins this process by promoting a continuous flow of materials within construction systems rather than a linear extract–use–dispose model [1,2]. However, the growing demand for infrastructure continues to place significant strain on natural resources, highlighting both the opportunities and challenges of implementing sustainable material management practices [13].

Within this framework, MUPs serve as central instruments for coordinating how materials are sourced, processed, and reused within and between projects. An effective MUP provides an operational link between policy intent and project-level implementation, ensuring that reclaimed materials are systematically evaluated for potential reuse through upcycling in new pavement layers [9,10]. The interrelationship among these elements, including client requirements, design decisions, and economic viability, is represented in Figure 1, which illustrates the conceptual structure of a typical MUP.

At a macroscopic level, MUPs support coordinated planning across multiple projects and regions, reducing duplication of quarrying and material transportation [9,19]. At a microscopic level, they address project-specific challenges such as local material variability, cost–benefit trade-offs, and testing constraints. In practice, this framework promotes collaboration between clients, designers, and contractors to optimise material flow, maintain uniform quality standards, and minimise environmental impacts [9,20]. The generic framework for recycling of road materials for an effective and sustainable material utilisation plan for road construction is presented in Figure 2.

Figure 2 depicts how the performance of reclaimed materials could be optimised through systematic cost and quality management strategies. It demonstrated that when the cost of natural materials remains higher than the properly processed reclaimed materials and when environmental externalities are accounted for, recycling–upcycling yields measurable economic and ecological advantages [4,21,22,23].

Technological advances such as geopolymerisation, cement stabilisation, and nanotechnology have further improved the structural and environmental performance of recycled and upcycled road materials [2,22,23,24]. However, the integration of these techniques into routine design and construction is constrained by the absence of standardised specifications, limited testing capacity, and misalignment between academic curricula and industry practice [9,21,25]. These institutional barriers underscore the need for coordinated reforms, particularly clearer design specifications for reclaimable materials, incentive frameworks for contractors, and updated engineering education programmes to mainstream upcycling within South Africa’s road construction sector. In addition, the adoption of upcycling is influenced by the internal recycling and quality-control regulations of production companies, which remain largely unstandardised across the South African road materials industry. Most quarries and aggregate suppliers operate under environmental authorisations rather than performance-based recycling frameworks, thereby creating inconsistencies between private-sector production controls and public-sector design specifications. This regulatory misalignment limits the consistent incorporation of reclaimed materials into project-level MUPs and constrains coordination between producers and designers [3,6].

Furthermore, project coordination across multiple stakeholders presents a persistent implementation challenge. Effective material management requires synchronised decision-making and transparent communication between clients, consultants, and contractors. However, fragmented institutional structures often result in inefficiencies and lost opportunities for reuse [4]. As Lavikka et al. [26] noted, digital platforms such as Building Information Modelling (BIM) can significantly enhance inter-project coordination, traceability, and performance monitoring. Despite these benefits, adoption remains limited due to cost, complexity, and organisational inertia, highlighting the need for systemic transformation in materials management practices [9].

Overall, this theoretical framework positions upcycling as both a technical innovation and an institutional reform process. It integrates circular economy theory, project management principles, and engineering design to explain how economic viability, client responsibility, and coordination interact to influence upcycling adoption in MUPs. In contexts such as South Africa, where material scarcity and infrastructure backlogs coexist, the framework provides a foundation for understanding and improving the technical feasibility and sustainability of road construction materials.

2. Materials and Methods

2.1. The Case Study

This study adopted a mixed-methods approach to investigate the institutional, economic, and technical factors influencing the adoption of upcycling within MUPs for a typical South African road project.

The process alleviates limitations of a single method [27]; however, it provides sufficient methods to investigate the intricacies and trends that respond to the research questions [28]. The approach combined semi-structured interviews with a structured questionnaire survey to triangulate perceptions from multiple professional categories or stakeholders involved in the National Route 3 (N3) upgrade project.

The N3 is integral to the economic growth of Southern Africa. A growing Southern African population has placed this strategic corridor under severe pressure, requiring substantial upgrading of portions of the corridor. This corridor, also referred to as the Durban-Free State–South African Government’s key strategic integrated projects (SIP2) that forms part of the National Development Plan. The need for the project arose from increased traffic volumes resulting in declining levels of service on the N3 freeway. The freeway between Pietermaritzburg and Durban currently exceeds the South African National Road Agency Limited (SANRAL) permissible traffic density limit for the peak hour and the 30th highest hourly volume, respectively. Due to the substantial costs to upgrade the 80 km freeway, the route has been strategically split into thirteen reasonably sized work packages that form the collective N3 upgrade project. This corridor context provided an ideal testbed for examining upcycling adoption, as it represents the complex institutional, technical, and logistical structures typical of South Africa’s major road projects. While the study draws data from one corridor, its strategic scope, diversity of stakeholders, and multi-package structure enhance the transferability of findings to other large-scale infrastructure programmes in similar contexts.

2.2. Research Design

This study adopted a convergent mixed-methods design, combining qualitative thematic analysis with quantitative descriptive and correlational analysis [29]. The design was chosen to integrate in-depth qualitative understanding with quantitative validation of the factors influencing the adoption of upcycling within MUPs. Qualitative methods were used to explore why certain barriers and enablers existed, while quantitative techniques tested how strongly these factors were associated with practice. Semi-structured interviews were conducted with nine key professionals engaged in project management, materials testing, and design engineering on the National Route 3 upgrade project. These interviews provided insight into institutional culture, decision-making processes, and perceived risks surrounding upcycling.

A structured questionnaire survey was then administered to thirty-two respondents drawn from the same professional ecosystem to measure the prevalence and strength of their perceptions across disciplines. The design ensured qualitative alignment between the identified themes and statistical constructs validated through Cronbach’s Alpha and Pearson correlation coefficient values. The semi-structured interviews and questionnaires were used to collect both qualitative and quantitative data, respectively [30,31]. This flexible format allowed for modifications of questions based on the participants’ responses, ensuring alignment with study objectives [32]. The integration of interview and survey data generated a coherent mixed-methods dataset that contributed to the validity and dependability of the study findings [32,33]. Within the context of the N3 upgrade project, which includes a corridor of multiple projects, this design facilitated the examination of both project-specific practices and broader institutional tendencies typical of South African road projects.

Although the empirical data were drawn from a single programme, the corridor’s national strategic importance, multi-package structure, and diverse stakeholder composition strengthen the transferability rather than statistical generalisability of the study’s conclusions to other large-scale infrastructure contexts.

2.3. Sampling and Representativeness

The study employed a purposive sampling approach within the defined project context rather than random selection across the national industry. This is appropriate when the goal is to obtain in-depth insights from participants with specific knowledge or decision-making experience relative to the research focus [31,34,35]. The selected participants, therefore, comprised stakeholders directly involved in project management, materials testing, and pavement design on the National Route 3 upgrade. While this approach limits the statistical generalisability of findings, it enhances their analytical depth and contextual validity by situating the results within a realistic and practice-based environment [35,36]. Consequently, the study positions its outcomes as analytically transferable rather than universally generalisable; that is, the insights and relationships identified are relevant to other infrastructure projects with comparable institutional and technical conditions [37].

To enhance balance and reduce bias within the purposively identified participant groups, a probability-informed approach consistent with standard methodological guidance [38] was applied during the survey phase. This ensured that all individuals within each identified category (e.g., project managers, materials engineers, and laboratory testers) had equal opportunity to participate, thereby improving representativeness while maintaining alignment with the study’s purposive framework [39,40,41]. Being a mixed-methods research design, the qualitative aspect considered nine participants, while the quantitative approach used thirty-two participants from the target population. Although the final sample size appeared relatively small, it was acceptable for the study’s scope and design [42,43]. In qualitative research, smaller, targeted samples were preferred to allow for in-depth exploration and thematic saturation [29], while on the other hand, the thirty-two respondents used for the quantitative method represented a substantial proportion of the targeted population, since the study focused on a specific and specialised workforce that represents the population under investigation.

2.4. Data Collection

Data collection procedures were designed to align with the mixed-methods framework, ensuring complementarity between the qualitative and quantitative strands.

The qualitative data collection process involved the use of voice recording platforms for recording and transcribing the responses based on stakeholders’ perceptions on the adoption of upcycling for road construction in South Africa. Permissions were requested from the respondents before the start of the interview, and the activation of the recording and transcribing systems [42]. This approach minimised the duration of the interview [32]. It involved the development of the interview schedule, which allowed respondents the opportunity to provide more information related to the subject [33,34], carrying out pilot semi-structured interviews, performing the face-to-face interviews, and transcribing records for data analysis. The online and face-to-face interviews were scheduled with participants to create the opportunity to obtain relevant information [43]. Transcribed responses were reviewed and coded, from which key themes and subthemes were identified to capture participants’ perspectives on the study objectives [38]. The results of the qualitative data collection approach were based on the direct experiences, opinions, and behaviour of human beings as meaning-making agents in their everyday lives. However, the respondents needed to understand the aim of the study as well as the research questions before granting the interviews [44].

The quantitative approach involved administering closed-ended research questionnaires to respondents to enable them to express their perceptions on the concept of upcycling in road construction in South Africa. The validation of the research instrument involved piloting it through an interview schedule with experts in the industry, aimed at reviewing it to confirm that all key subjects and elements relevant to answering the research questions were included [34]. The process gave insight into whether the interview schedule was clear, unambiguous, understandable, and concise enough for the study. This approach solicited quantifiable data from respondents to be analysed using statistical methods for objective and unequivocal decisions [31]. Efforts to minimise bias were ensured by inviting participants from all relevant professional categories, maintaining balance across roles and disciplines within the project. Major sections of the questionnaire were as follows: Part A for social demographic-related questions (age, gender, education, experience, and position occupied in the current industry), and the understanding of the MUPs and the various options to upcycle materials. Part B focused on the Laboratory testers and sought to determine the factors affecting the testing of materials. Part C applied to pavement design engineers and sought to understand the challenges with designing for upcycling, and Part D referred to all participants and sought to understand the factors affecting the MUPs. The questionnaire was structured using a five-point Likert scale, with response options defined as follows: 1 = Strongly Disagree, 2 = Disagree, 3 = Neutral, 4 = Agree, and 5 = Strongly Agree, ensuring comprehensive representation of respondents’ levels of agreement [42].

In all approaches, ethical approval for the study was obtained from the University of KwaZulu-Natal, and informed consent was provided for all participants. Both instruments—the interview guide and questionnaire—were structured around the same conceptual framework, facilitating integration of qualitative, and quantitative findings during analysis.

2.5. Data Analysis

According to Braun and Clarke [45], thematic Analysis is a systematic technique for methodically identifying, categorising, and presenting insights into patterns of meaning, also referred to as themes, that are present in a dataset. The process involves six chronological steps:

• Step 1: Data familiarisation, which entails transcription of respondents’ responses by listening to the recording and writing down the key understandings.
• Step 2: Generating the initial codes, which involves reviewing the transcript to identify initial codes based on comments that were relevant in the context of the research.
• Step 3: Searching for themes—this involves the interpretation and categorisation of responses into themes and subthemes.
• Step 4: Reviewing identified themes—completion of the initial search for themes, then scrutinising for coherence and appropriateness.
• Step 5: Defining and naming themes—this involved the identification of themes, and iteratively refining and defining to correctly describe the essence of the themes for the study.
• Step 6: Producing the report—by converting the themes into responses for the research questions. The final report was not limited to the description of the themes, but also included the analysis, which was supported by the literature and responded to the research questions [45].

Quantitative data were analysed using descriptive statistical parameters to explain frequency distributions and identify patterns within the dataset [46,47]. The essential parameters used were the sum, mean, and standard deviation, estimated as the arithmetic average or the representative value, and a measure of how far the data is spread around the mean or dispersion. The reliability test was employed to check the effectiveness of the quantitative research instrument. It attempted to test the suitability of the instrument for measuring variability and coherence among the variables, focusing on consistency. This confirms the internal consistency across all factors (Cronbach’s Alpha Value α > 0.60), and the closeness of individual questions related to each other [47]. Also, the Pearson correlation test was used to examine the relationship between factors influencing the adoption of upcycling among stakeholders at 5% significance level [48,49].

Results from both analytical strands were compared and merged during interpretation, allowing qualitative themes to clarify the underlying causes of quantitative patterns. This methodological triangulation strengthened the dependability, validity, and interpretive depth of the study’s findings.

3. Results

3.1. Respondent Profile

The professional composition and experience distribution of respondents are summarised in Figure 3.

As illustrated in Figure 3, the sample comprised a diverse group of professionals involved in road construction project delivery, including project managers (38%), pavement and materials engineers (28%), and materials technicians (9%). Smaller proportions of respondents were resident engineers (9%), contract engineers (3%), and contract directors (3%), with a further 9% classified as “other” professional categories.

The experience profile of participants showed that 81% had more than ten years of industry experience, while 19% had less than ten years. This distribution indicated that the dataset predominantly reflects the perspectives of seasoned professionals with substantial exposure to materials management, design, and construction supervision. At the same time, the inclusion of early-career practitioners ensured representation of emerging viewpoints, providing a balanced and credible basis for interpreting stakeholder perceptions.

Overall, the composition of respondents mirrored the multidisciplinary structure of South Africa’s road construction sector, thereby enhancing the contextual reliability and practical relevance of the findings [50,51].

3.2. Factors Affecting the Adoption of Upcycling in MUPs

3.2.1. Existing Culture of Road MUPs

According to the respondents, a typical MUP for a road construction project in South Africa usually assumes the trends shown in

Table 1. Existing material recycling for road project MUPs.

Items	Questions	1	2	3	4	5	Total	Mean	SD
P1	The utilisation of reclaimed materials within a project is restricted to the project limits	9	8	2	8	5	32	2.75	1.50
		28%	25%	6%	25%	16%	100%
P2	The utilisation of materials between adjacent projects is limited to surplus reclaimed material	4	7	2	10	9	32	3.41	1.43
		13%	25%	19%	31%	22%	100%
P3	The movement of reclaimed materials between projects imposes a contractual risk	1	8	6	10	7	32	3.44	1.19
		3%	25%	19%	31%	22%	100%
P4	It is economically viable to utilise a quarry owned by the client near the project	0	0	5	11	16	32	4.34	0.75
		0%	0%	16%	34%	50%	100%
P5	It is economically viable to utilise a stockpile site owned by the client near the project	0	0	1	15	16	32	4.47	0.57
		0%	0%	3%	47%	50%	100%
	Cluster Values							3.682	1.088

.

The results showed that reuse of reclaimed materials was generally confined within the individual project boundaries (mean = 2.75, SD = 1.50). However, the respondents strongly agreed that the use of client-owned quarries and stockpile sites located near project areas enhanced the overall cost efficiency (means > 4.3). In contrast, there was only moderate agreement regarding the reuse of surplus materials between adjacent projects and the perceived contractual risks associated with moving materials across sites (mean < 3.5).

The average of means in a given cluster or cluster mean of 3.682 (SD = 1.088) indicated the combined responses from subthemes reflecting responses to the major theme on material reuse behaviour and project-level decision factors, or the existing culture on material recycling for road project MUP. This indicates that, overall, logistical and contractual factors have a greater influence on reuse practices than the sustainability objectives. These findings are consistent with previous studies by Hoy et al. [4] and Wu et al. [52], who observed that operational constraints often take precedence over environmental considerations in material recovery and reuse.

3.2.2. Recycling for the Road Surface Layer

Results for the suitability of recycling existing road materials for the construction of new pavement layers, like the surface layer, are presented in

Table 2. Recycling for road surface layer.

Items	Questions	1	2	3	4	5	Total	Mean	SD
P10	The reclaimed surface layer can be recycled and utilised in the surface layer of the new pavement	0	7	4	8	13	32	3.84	1.19
		0%	22%	13%	25%	41%	100%
P11	The reclaimed surface layer can be downcycled and utilised in the new pavement	0	2	7	11	12	32	4.03	0.93
		0%	6%	22%	34%	38%	100%
P12	The reclaimed surface layer can be downcycled and utilised as fill for the project	7	6	6	7	6	32	2.97	1.45
		22%	19%	19%	22%	19%	100%
	Cluster Values							3.623	1.19

.

Respondents generally supported the recycling and downcycling of reclaimed surface layers. They agreed that such materials could be recycled and reused in the surface layer of new pavements (mean = 3.84, SD = 1.19) and downcycled for use in underlying pavement layers (mean = 4.03, SD = 0.93). However, there was a weaker agreement for using the surfacing layer as fill (mean = 2.97, SD = 1.45), suggesting that respondents perceive greater value in reusing the surface materials for higher-order pavement applications rather than for low-value fill.

The overall cluster mean of 3.623 (SD = 1.19) reinforced this trend, indicating a broad acceptance of recycling and downcycling practices for reclaimed surface materials in road construction. This agreement reflects the growing acceptance of reuse in upper pavement layers [10,15].

3.2.3. Recycling for Base Layer

Results for the perception of respondents on recycling for the production of the base layer for new road pavement construction are presented in

Table 3. Considerations for producing base layer.

Items	Questions	1	2	3	4	5	Total	Mean	SD
P13	The reclaimed base layer can be upcycled and utilised in the surface layer of the new pavement	10	8	8	4	2	32	2.38	1.24
		31%	25%	25%	13%	6%	100%
P14	The reclaimed base layer can be recycled and utilised in the base layer of the new pavement	2	3	12	7	8	32	3.50	1.16
		6%	9%	38%	22%	25%	100%
P15	The reclaimed base layer can be downcycled and utilised in the new Pavement	0	1	5	13	13	32	4.19	0.82
		0%	3%	16%	41%	41%	100%
P16	The reclaimed base layer can be downcycled and utilised as fill for the project	5	4	9	6	8	32	3.25	1.39
		16%	13%	28%	19%	25%	100%
	Cluster Values							3.330	1.153

.

Respondents disagreed with the practice of upcycling the existing base layer for use in surface courses (mean = 2.38, SD = 1.24), but supported recycling within the base layer itself (mean = 3.50, SD = 1.16) and downcycling into lower pavement layers (mean = 4.19, SD = 0.82). Qualitative responses indicated that engineers viewed base materials as technically stable but not sufficiently tested for higher-order functional reuse.

The cluster mean of 3.330 (SD = 1.15), which was slightly above the neutral limit (3.0), reflected a general cautious approach, showing concerns about performance. These results echoed stakeholder scepticism reported in prior studies [10], where uncertainty around testing and specifications limited the willingness to upcycle base materials into road surface applications.

3.2.4. Recycling for the Subbase Layer

Results of investigations into the acceptance of upcycling for the recycled subbase layer for road construction in South Africa are presented in

Table 4. Considerations for producing subbase layer.

Items	Questions	1	2	3	4	5	Total	Mean	SD
P17	The reclaimed subbase layer can be upcycled and utilised in the new pavement	9	2	14	3	4	32	2.72	1.33
		28%	6%	44%	9%	13%	100%
P18	The reclaimed subbase layer can be recycled and utilized in the subbase layer of the new pavement	3	3	11	6	9	32	3.47	1.27
		9%	9%	32%	19%	28%	100%
P19	The reclaimed subbase layer can be downcycled and utilised in the new pavement	1	4	6	10	11	32	3.81	1.15
		3%	13%	19%	31%	34%	100%
P20	The reclaimed subbase layer can be downcycled and utilised as fill for the project	2	6	7	7	10	32	3.53	1.29
		6%	19%	22%	22%	31%	100%
	Cluster Values							3.383	1.26

.

Upcycling of the subbase layer was met with mixed opinions (mean = 2.72, SD = 1.33). Respondents showed moderate agreement with recycling within the subbase (mean = 3.47, SD = 1.27) and downcycling into fill or lower layers (means = 3.81 and 3.53; SD = 1.15 and 1.29). Stakeholders generally supported materials reuse, but not necessarily upcycling, indicating a continued preference for recycling and reuse rather than value-added upcycling. The cluster mean of 3.383 (SD = 1.26) underscored this conservative approach and highlights the need for clearer performance criteria and improved testing protocols to build confidence in subbase upcycling for sustainable pavement design [10].

3.2.5. Considerations for Subgrade Layers

The respondents’ perception of recycling some subgrade layers is presented in

Table 5. Subgrade layer.

Items	Questions	1	2	3	4	5	Total	Mean	SD
P21	The reclaimed Subgrade layer can be upcycled and utilised in the new pavement	10	6	11	1	4	32	2.47	1.32
		31%	19%	34%	3%	13%	100%
P22	The reclaimed Subgrade layer can be recycled and utilised in the Subgrade layers of the new pavement	1	2	8	11	10	32	3.84	1.05
		3%	6%	25%	34%	31%	100%
P23	The reclaimed Subgrade layer can be downcycled and utilised as fill for the project	3	1	4	12	12	32	3.91	1.23
		9%	3%	13%	38%	38%	100%
	Cluster Values							3.407	1.20

.

Respondents did not support upcycling subgrade materials for the higher layer (mean = 2.47, SD = 1.32), but agreed with recycling and downcycling for fill and subgrade reuse (means = 3.84 and 3.91). The findings suggest a risk-averse engineering culture, where stability and proven performance outweigh sustainability objectives. Reuse acceptance decreased progressively from surface to subgrade layers, reflecting confidence in recycling only when risk is minimal. The cluster mean of 3.407 (SD = 1.20) indicates limited acceptance of upcycling and continued caution among practitioners.

3.2.6. Client’s Specifications

The client’s specifications and design requirements influenced the perception of road experts on material utilisation through the integration of upcycling in the MUP for road construction in South Africa, as shown in

Table 6. The specifications influencing materials utilisation.

Items	Questions	1	2	3	4	5	Total	Mean	SD
P24:	The clients’ specifications are a barrier to the recycling of materials	5	5	5	10	7	32	3.28	1.40
		16%	16%	16%	31%	22%	100%
P25:	It is the responsibility of the client to specify the minimum % of reclaimable material to be used in each layer of the new pavement	5	5	5	10	7	32	3.28	1.39
		16%	16%	16%	31%	22%	100%
P26:	There is limited awareness of the need for upcycling of the existing pavement layers	0	2	1	16	13	32	4.25	0.80
		0%	6%	3%	50%	41%	100%
P27:	The engineer is responsible for designing the upcycling of the existing pavement layers	0	3	6	9	14	32	4.06	1.01
		0%	9%	19%	28%	44%	100%
P28:	The current testing regime during the design phase is insufficient to inform the upcycling of the existing pavement layers	2	2	9	14	5	32	3.56	1.05
		6%	6%	28%	44%	16%	100%
	Cluster Values							3.686	1.13

.

Table 6 revealed that respondents viewed client specifications as a barrier to recycling (mean = 3.28, SD = 1.40) but strongly agreed that engineers should design for upcycling (mean = 4.06, SD = 1.01). There was strong agreement that limited awareness and inadequate design responsibility hindered the adoption of upcycling (mean > 4.00, SD < 1.2). Also, the current testing regimes were insufficient to guide design decisions; nevertheless, testing significantly influenced the adoption (mean = 3.56, SD = 1.05). Although engineers support the concept of reuse, tender and contract documents seldom specify measurable reuse targets. Therefore, the cluster values (mean = 3.686, SD = 1.13) justified the assertion that institutional awareness, specification clarity, and testing limitations constrain the adoption of upcycling. These findings highlight ongoing uncertainty regarding long-term performance and the absence of a standardised testing framework reported by Jamshidi and White [51]. This implied that stakeholders recognised that upcycling could help reduce depletion of natural aggregates, but practical adoption remained limited by institutional and technical constraints or design specifications, which conformed with findings in previous studies on sustainable pavement materials [2,3,15]. This gap mirrors governance challenges identified by Gobbo et al. [7], thereby suggesting the need for clearer policy direction.

3.2.7. Material Cost

The influence of material cost on the integration of upcycling in MUP was examined using the responses obtained from the survey. Results of the analysis are presented in

Table 7. Cost of natural resources in a flexible pavement project.

Items	Questions	1	2	3	4	5	Total	Mean	SD
P29:	The process of recycling has cost implications, and it is easier to spoil materials	11	7	9	3	2	32	2.31	1.23
		34%	22%	28%	9%	6%	100%
P30:	The process of upcycling has cost implications, and it is easier to downcycle materials	4	3	11	7	7	32	3.31	1.28
		13%	9%	34%	22%	22%	100%
P31:	Contractors need to be incentivised to reclaim and upcycle the existing pavement layers	1	3	7	12	9	32	3.78	1.07
		0%	6%	3%	50%	41%	100%
P32:	The introduction of a surcharge when spoiling material at a landfill site will increase the efficient utilisation of existing pavement layers in the new pavement	3	1	8	10	10	32	3.71	1.22
		9%	3%	25%	31%	31%	100%
	Cluster Values							3.278	1.20

.

Material cost was recognised as a key determinant (Table 7). Respondents disagreed that spoiling materials was cost-effective (mean = 2.31, SD = 1.23) but supported financial incentives (mean = 3.78, SD = 1.07) and landfill surcharges (mean = 3.71, SD = 1.22) to encourage reuse. These findings emphasise that economic drivers strongly influenced material utilisation decisions. Qualitative findings indicated that introducing financial incentives such as rebates for recycled content could redirect contractor behaviour toward upcycling. The cluster mean of 3.279 (SD = 1.20) supports the conclusion that financial incentives could play a vital role in promoting sustainable material reuse.

3.3. Reliability Test

The reliability test was used to assess the strength of the decision variables employed in the study. According to Gravetter and Wallnau [50], an Alpha Coefficient Range of 0.6 to <0.70 strength of association could be regarded as moderate, 0.7 to <0.8 as good, and >0.8 as very good. Cronbach’s Alpha findings of the study variables are presented in

Table 8. Reliability test of decision variables.

Study Variables	Cronbach’s Alpha	Counts
Factor 1—Reusing the existing reclaimed materials	0.88	7
Factor 2—Downcycling material to fill	0.86	4
Factor 3—Limited design for upcycling	0.77	5
Factor 4—Optimising costs	0.79	5
Factor 5—Client’s responsibilities	0.81	5
Factor 6—Reluctance to upcycle	0.64	4
Factor 7—Economic viability of materials utilisation	0.66	3

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Cronbach’s Alpha values ranged from 0.64 to 0.88, indicating moderate to high internal consistency across the measured factors, confirming that the survey items were reliable for this study and relevant for subsequent correlation analysis.

3.4. Correlation Analysis

Pearson’s Product-Moment correlation analysis was used to examine the relationship between the variables in terms of proportionality, such that when one variable changes in value, the other tends to change in a specific direction, either positive or negative. The magnitude of the change was measured using Pearson’s (r) correlation, which ranged between −1 for a perfect negative correlation to +1 for a perfect positive correlation at 5% level of significance [45]. The correlation benchmarks were defined as 0.10 ≤ r ≤ 0.29 for small, 0.30 ≤ r ≤ 0.49 for medium, and 0.50 ≤ r ≤ 1.00 for large effect. The correlation between influencing factors considered by this study is presented in

Table 9. Correlation analysis of influencing factors.

	Factor 1:	Factor 2:	Factor 3:	Factor 4:	Factor 5:	Factor 6:	Factor 7:
Factor 1:	1
Factor 2:	0.198	1
Factor 3:	0.302	–0.221	1
Factor 4:	0.330	–0.117	0.142	1
Factor 5:	0.209	–0.146	–0.064	–0.007	1
Factor 6:	0.030	–0.048	0.296	0.136	–0.042	1
Factor 7:	0.353	–0.400	0.209	0.193	0.174	0.108	1

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These results suggest that cost-sensitive projects with clear client guidance were more likely to incorporate reclaimed materials. Interview data supported this claim, noting that consistent specification and incentive frameworks could encourage upcycling practices. Similar mechanisms were advocated by Singh and Gupta [24] for promoting the adoption of the circular economy. A positive relationship between Factor 1 (Reusing existing reclaimed materials) and Factor 4 (Optimising costs) (r = 0.330) indicated that the respondents associated material reuse with cost-saving opportunities. Similarly, Factor 1 also correlated moderately with Factor 7 (Economic viability of material utilisation) (r = 0.353), suggesting that greater reuse aligns with perceptions of economic efficiency.

The weak positive correlation between Factor 3 (Limited design for upcycling) and Factor 6 (Reluctance to upcycle) (r = 0.296) implied that where design limitations were perceived, the hesitation to implement upcycling increased, reinforcing the importance of technical guidance and design standards.

Conversely, the negative correlation between Factor 2 (Downcycling material to fill) and both Factor 3 (Limited design for upcycling) (r = −0.221) and Factor 7 (Economic viability) (r = −0.400) suggested that a stronger preference for downcycling may undermine innovation and economic efficiency. In practice, this indicates that defaulting to low-value reuse (fill) reflects lost economic and environmental opportunities. These insights emphasise that improving design capability and financial incentives could strengthen the perceived viability of sustainable material utilisation.

In summary, these findings highlight that, while technical feasibility and moderate willingness exist, the broader perception of stakeholders on the adoption of upcycling is constrained by institutional inertia, clients’ and designs’ specification rigidity, and perceived contractual risks.

4. Conclusions

This mixed-methods case study provided empirical evidence that the adoption of upcycling in the South African road construction industry was constrained more by institutional and procedural barriers than by technical limitations. Competitive tendering, limited testing capacity, and insufficient design-stage coordination emerged as the most critical obstacles. Correlation analysis confirmed that material reuse and cost optimisation were positively related (r = 0.353), while downcycling showed a moderate negative correlation with cost (r = −0.400), indicating that cost perceptions significantly influence materials use choice. Design frameworks (r = 0.302) and institutional policies (r = 0.330) were also positively linked to upcycling adoption, showing that coordinated planning and clear governance improve decision outcomes.

A strong consensus emerged among stakeholders regarding the long-term cost and environmental benefits of upcycling when supported by clear client specifications and policy incentives. Embedding upcycling requirements into design guidelines could therefore advance material efficiency and carbon reduction in South Africa’s road sector.

Although the study was limited in sample size, it provides a validated diagnostic framework that can inform future researchers and policymakers on circular material feasibility. By framing upcycling within a practical policy, procurement, and educational framework, this study supports South Africa’s transition towards a sustainable, resource-efficient, and low-carbon road construction industry.