Integrating 3D Printing into Traditional Construction Supply Chains: A Systematic Review of Challenges, Benefits and Framework Proposals ^†

Abstract

The purpose of this study is to highlight the existing challenges encountered by traditional construction supply chains and the potential advantages that 3D printing can offer to overcome these challenges. A systematic review was conducted, which revealed a total of eleven (11) obstacles concerning material, cost, and environment. Moreover, eight (8) benefits of 3D printing were identified from various sources in the literature. Furthermore, a framework based on the literature has been proposed to demonstrate how these challenges, functions and benefits can interact with each other in the supply chain. The aim is to explore their impact on each other.

1. Introduction

Dealing with multiple issues around it is a commonplace in today’s world, the increasing population being one significant factor. To accommodate everyone in this population with shelters, the construction industry is continuously working to build homes. The construction supply chain (CSC) plays a crucial role in facilitating and impacting construction activities by building desired homes and shelters for people in need. CSC is a complex network where the key partners are clients, consultants, designers, contractors, subcontractors and raw materials suppliers. The partners interact for the exchange of knowledge, information and funds and to maintain contractual relationships [1]. According to the literature, there are eight (8) key functions of CSC, as shown in

Table 1. Functions of CSC.

Functions Code	Functions	Description
F1	Planning	Materials and other specifications for new builds, planning regarding modes of transportation, network and machine and labor capacity.
F2	Tendering	Placement of the actual working procedure and planning to conduct the construction.
F3	Sourcing	Decision regarding the sources of raw materials and fabricated parts.
F4	Raw materials production	Producing other ingredients in material format to be able to be constructed.
F5	Fabrication of parts	Assembly of smaller parts.
F6	Installation on site	Assembly of fabricated large parts on the construction site.
F7	Waste management	Waste removal process and demolition of parts.
F8	Hand over to the customer	Delivering the finished structure.

[2,3].

CSC has always been surrounded by various challenges due to its unique, on-demand, temporary and highly customized nature [4]. One of the primary challenges is the need for many skilled workers. Another one revolves around multiple types of raw materials, which require proper inventory management to deal with potential shortages. CSC involves numerous interrelated processes and sub-processes where maintaining their order is also crucial. Additionally, the fragmented supply chain presents a significant concern as multiple small and large suppliers are working together to complete the work. Moreover, the increasing need for environmental sustainability is a major concern given the environmental issues happening around the world. As one of the core components of the fourth industrial revolution, Industry 4.0, additive manufacturing (AM), also known as 3D printing (3DP), has recently been demonstrated to significantly influence CSC through the ability to thwart the challenges. Specifically, 3D concrete printing (3DCP), a process of 3DP for the construction field, is a technology where concrete slurry is deposited layer by layer from a nozzle to form concrete walls with complete design freedom [5]. This technology offers advantages such as less waste, rapid production, customization and freedom of house design, low energy consumption and less labor demand.

At present, there is a significant shortage and need for houses in remote areas, specifically in North America. For example, the Canadian government has taken the initiative to reduce the risk of homelessness through its house-building project in Alberta, which employs 3DCP [6]. This technology has great potential to address various problems of CSC as well as tackle housing shortages. The innovative construction method offered by 3DCP has the potential to reduce the requirement for a large and highly skilled workforce. With time being a significant factor in construction projects, 3DCP can construct houses within a short duration of time. The freedom of using complex geometry and materials enables 3DCP to be environmentally friendly, causing the least harm to the environment. As a result, 3DCP has emerged as an effective technology to address the housing crisis in remote communities around the globe [7]. However, there are some challenges with 3DCP, which limits its widespread adoption. One vital challenge is material-related, i.e., material printability (how the materials will be inserted and printed on the nozzle), buildability (how quickly the material bonds in the layers) and open time (the limited time within which the material must be printed). Another challenge is related to the 3D printers, which come from the size of the structures, as 3D printers cannot yet develop huge building structures like multi-storied office buildings. The requirement for a controlled construction site environment in an open space is yet another concern. Due to the automated nature of 3DCP, its implementation in construction may reduce the basic manual tasks, resulting in a fall of labor force engagement rates, and thus a reduction in employment scopes. Additionally, there are limited number of printing methods based on materials, and also the material type decides which process to use [8,9].

The process of 3DCP is a relatively recent technological innovation in CSC. Thus, there is a need for a holistic view to comprehend its positive impact on addressing the challenges faced by the traditional CSC. This paper aims to contribute to identifying the current challenges faced by the traditional CSC at present and the benefits that 3DCP can offer to the CSC to cope with the challenges efficiently. Then, a framework will be provided for categorizing these challenges and benefits based on their impacts on the functions of CSC. By mapping the functions with the challenges and benefits, this framework will help anyone achieve a better understanding of how 3DCP technology can help overcome the challenges and improve the overall performance of CSC.

2. Research Methodology

For conducting this study, we have employed a two-phase methodology that covers identification, categorization and framework development. The flow of these steps has been demonstrated in Figure 1.

2.1. Phase 1: Identification of Challenges and Benefits

2.1.1. Search Strategy

The widely accepted and applied methodology technique, Preferred Reporting Items for Systematic Reviews and Meta-analyses (PRISMA), was utilized for the literature review in this work [10,11]. PRISMA is used to ensure transparency and systematic procedure in reviewing the literature.

The search for sources from the literature was limited to three databases: Google Scholar, Web of Science and Science Direct. The exploration in these databases was focused on 13 keywords, including 3D printing, additive manufacturing, supply chain, construction, building industry, construction industry, construction work, construction project, challenges, issues, problems and impacts. The keywords finally used were combinations of these. There were two focuses of these searches: one is for the challenges of CSC and another is the benefits or impacts of 3DCP on CSC.

2.1.2. Eligibility Criteria and Screening Process

This study is based on certain criteria for selecting sources from literature. The literature (i) must contain the specific combinations of keywords, as mentioned above, and the title should indicate a relationship between them; (ii) must be published within the last 6 years, i.e., between 2018 and 2023; (iii) includes journal articles (both reviews and research papers) and conference papers as acceptable sources for conducting literature reviews [12]. Among them, peer-reviewed journal articles and articles in professional journals including conference papers were used for this research. The last 6 years’ data were used for conducting the review, as there was very little work conducted in the previous 10–15 years focusing on 3DCP and CSC, as 3DCP is a relatively new addition to the supply chain arena. Moreover, Abramo, G. et al. suggested using a publication period of three years or more for the literature review [13]. Considering this inclusion criterion, articles before 2018 were ruled out.

The PRISMA systematic process of screening and obtaining the final number of articles in this research work entails the following steps:

(i)

Identification (initial screening) is conducted with the titles having any of the combinations of the keywords. Around 25 combinations of keywords were used to conduct the search.

(ii)

Eligibility (secondary, tertiary, quaternary screening) is where articles were filtered out based on years of publication, type of paper, relevance and duplication.

(iii)

Inclusion (final selection) is the last step of the process, where the articles were reviewed based on the abstracts and a thorough skimming of the contents of the articles where required. After careful consideration, 15 articles were selected.

A brief PRISMA process is shown as a PRISMA flowchart in Figure 2.

2.2. Phase 2—Categorization and Framework

During this phase, various challenges related to the functions of CSC were identified and explained. The reasons behind how a specific CSC function can be affected by a specific challenge were also justified. As the number of studies related to 3DCP or AM and CSC are in the initial stages, an adequate number of relevant papers focusing on the mentioned justification were not found.

A framework has been developed by combining the findings from the literature with our understanding of the field of study. The framework outlines the challenges of CSC, the benefits of 3DCP on CSC and the functions of CSC. The challenges are grouped into several clusters based on the functions they can affect and the benefits of 3DCP based on the challenges they might solve.

Finally, proper reasoning has been provided with the linkages of the challenges and benefits of 3DCP in the Discussion Section. Here, a proper justification has been attempted to be provided about why the challenges may affect some specific functions and, similarly, how the benefits of 3DCP can alleviate those challenges. This discussion is drawn from the literature and basic knowledge of the topic of the study.

3. Results

3.1. Phase 1

3.1.1. PRISMA Search Specific Results

In the initial screening, a total of 15,960 articles (including both benefits and challenges) were found in the three databases. In the next step, a total of 10,605 articles were retrieved. In the tertiary level of screening, a total of 124 articles were retained. In the fourth level, 120 articles were obtained. Finally, in the last step of the process, 15 articles remained for review—9 for the challenges of CSC and 6 for the benefits of 3DCP on CSC.

3.1.2. Literature Analysis

Challenges of Conventional CSC: Numerous studies have highlighted the challenges faced by the conventional CSC, which hampers its operational and strategic efficiencies. One of the primary challenges is the limited time allocated for planning (C1), where the efficiency of planning and tendering is compromised due to limited time allocation in these initial stages [14]. Another challenge is the significant amount of waste and pollution generated (C2) during construction and demolition, which severely impacts the environment [15]. The requirement for multiple types of materials results in delays due to non-synchronization of multiple lead times; also, delays may arise from ineffective planning during disruption and uncertainties and the complexity of the supply chain (C3), making it difficult to maintain project schedule, which can result in more time than the committed project completion time [4,16,17]. Traditional construction work is burdened with a large number of skilled workers (C4), which can be a headache considering the shortage of skilled laborers [18]. Material shortages (C5) for common construction materials are a key issue [16]. The uncertainty of future cost (due to disruptions), non-availability of raw materials at the planned price and uncertainty of labor supply and cost can increase the cost of CSC (C6) [16]. Communication problem (C7) becomes a matter of concern due to the missing proactive communications among geographically separated parties, lack of trust and unwillingness to share key information among the parties [19]. Construction work is notorious for a large amount of energy consumption and the emission of an alarming number of pollutants (C8). It is also a reason for the loss of green places, which positions it as one of the biggest challenges of the CSC [20]. Often, the lack of motivation to improve the SC network (C9), due to the unclear statement about the beneficiary of the improvement of the network relationships, damages the performance of the whole SC [1]. Safety issues (C10) are a very concerning issue due to poor working conditions, a lack of safety training and cultural and language barriers in the case of migrant workers [21]. Construction activities raise the concern for environmental sustainability (C11) and it is a matter of critical demand for CSC due to the demand for low-carbon emission projects and more efficient construction processes, which may require additional costs to implement [22].

Benefits of 3DCP in CSC: One of the recent technologies that can assist with the challenges mentioned above is 3DCP. Several studies have identified that implementing 3DCP in CSC can provide unique benefits that can help in alleviating the challenges. Material freedom (B1), such as the opportunity to use natural materials or by-products of other processes, is one such significant benefit of 3DCP, which is likely to solve the material shortage issue of CSC [23]. Other benefits involve the application of environment-friendly structures, elimination of unnecessary waste, use of sustainable materials and reductions in greenhouse gas emissions through 3DCP, which can satisfy the requirement of environmental sustainability (B2) [6,8,15,24]. This benefit aims to achieve the requirement of environmental concerns of CSC. To be sure, 3DCP can help in reducing construction project costs (B3) by saving prototyping costs, reducing construction components and transportation-related costs, improving the packaging of parts and decreasing labor demand and cost, as many operations with this method can be performed without human involvement [6,9,15,24,25]. The automation feature of 3DCP can save a significant amount of time (B4), which is one key benefit of 3DCP, as it can help in faster delivery of construction projects due to the operability of 24/7 h [6,15]. By using locally available natural materials and thus reducing fuel consumption of transportation and by using efficient building insulation techniques, 3DCP can reduce energy consumption (B5) [15]. CSC is known as a source of huge energy consumption and the benefit of 3DCP can address this challenge. The elimination of several time-consuming steps and intermediary parties by implementing 3CCP, a less complex and trimmed supply chain (B6) can be achieved, which is likely to solve the coordination and communication issues of CSC [15]. As 3DCP allows the application of complex external and internal geometrics (B7) to improve the functionality or appearance of a building part, it is easier to create 3D visuals, which means that there is no need for building a prototype of the structure, reducing cost, time and effort [6,25,26]. This feature also allows for an extreme level of customization and chances of community engagement by including the thoughts and design ideas of the potential residents during the design process, which can greatly enhance the planning activities of the process [6]. The automation feature of 3DCP ensures safety in construction sites (B8) by shifting major hazardous tasks from human to machine, reducing the chances of accidents and injuries [6,8].

3.2. Phase 2

From the literature, it was revealed that some functions have direct linkage with challenges, while others have indirect linkages. To categorize and develop a framework for these functions, challenges and benefits, we have combined insights gained from the literature analysis and our own understanding. The detailed linkage will be discussed in Section 4. In this part, in Figure 3, we present a framework linking the challenges and functions of CSC and the benefits of 3DCP, i.e., the effects of each other on each other. However, it can be seen in the framework that a few challenges are in multiple clusters based on the functions they are affecting. To avoid repetition, we simplified it by linking them to a specific function individually. The benefits of 3DCP are also clustered to be simplified to link to a specific challenge cluster, where it is to be mentioned that an individual benefit may affect an individual challenge from the challenge cluster, but not the full cluster. A full-fledged description of how the linkages is working has been provided in the Discussion Section.

4. Discussion and Future Research Directions

In the previous section, we developed a framework. Now, in this section, we will discuss the framework: the justification for the functions, why and how they would be affected by the challenges and what benefits of 3DCP can thwart those challenges.

4.1. Discussion

The first challenge affects planning, tendering and sourcing functions [13] where sourcing decisions are taken for quick supplies to meet deadlines. 3DCP can help solve this issue because of its time-saving nature and reduced material lead time. The second one mainly affects the conversion functions, i.e., the fourth, fifth and sixth functions, as construction sites are responsible for huge waste and pollution generation, during the processing and installation of parts and demolition, if required [14]. The role of 3DCP here is to ensure environmental sustainability by generating very little waste and using less carbon-emitting processes. Fabrication and installation both are affected by the fourth (4th) challenge because of the need for a huge number of qualified workers [16], which can be solved with 3DCP by reducing the demand and cost for a large skilled workforce. The challenges of ‘material shortages’ and ‘increased cost’ can impact the third (3rd) and fourth functions as parties can aim for less used, less environmentally hampering materials, and sometimes the source of materials may need to produce them differently, along with alternative high-cost sourcing during sudden disruption, increasing the price of raw materials. Both can be solved by the usage of alternative raw materials, the reduction of project cost by reducing some steps in the chain and transportation and extra packaging costs, which 3DCP can offer. The challenge of excessive energy consumption impacts the fourth, fifth and sixth functions, as the consumption of energy occurs when something is being produced or converted. The automation, use of environmental structure, elimination of waste and natural resource usage feature of 3DCP can ensure environmental sustainability. The tenth (10th) challenge affects the first and fourth to seventh functions. To ensure safety in the work site, the planning phase needs to devise various mechanisms that require more time in planning, affecting all other functions. The use of functionally graded materials and automation features enable 3DCP to be a safe manufacturing method in this case. The challenge of environmental sustainability calls for measurements and procedures to be incorporated into all activities, as there is a need for construction activities to be less carbon emitting. The safety and environment-friendly features, structures and materials of 3DCP can be of great assistance in dealing with this.

Some challenges affect all the functions of the CSC, such as insufficient planning and delays [18], communication issues [18] and demotivation to enhance the SC network [1]. Thus, 3DCP can be a rescuer in these cases by streamlining the supply chain, constructing within a short timeframe and involving customers in the final design and planning process.

4.2. Future Research Direction

The identified challenges and benefits in this study require thorough validation through practical and expert experience. There is a need for further research to be conducted, which we plan to undertake soon. Our plan is to achieve the validation of the impacts of the challenges, benefits and functions on each other. Once we have the validation, our goal is to develop a final framework including mitigation strategies to alleviate the challenges. We believe the final work will help in the decision making in CSC. In doing this, we will employ EFA (exploratory factor analysis) for factorability and statistical analysis to seek validation and provide important explanations and implications for any CSC decision maker.

5. Conclusions

Through a systematic literature review, eleven (11) challenges and eight (8) benefits associated with the CSC and 3DCP, respectively, have been identified. The identified challenges are then linked to specific functions within the CSC, which is mostly based in the literature, along with some level of our knowledge and understanding. The justification focuses on each challenge’s impact on specific functions. A linkage between the benefits and the challenges of 3DCP is also provided. Based on this study, we can plan to validate this using expert feedback for the purpose of supporting the challenges, benefits and function, and the impact on each other.