3D Construction Printing Standing for Sustainability and Circularity: Material-Level Opportunities

Abstract

Three-dimensional Cementitious materials Printing (3DCP) is a cutting-edge technology for the construction industry. Three-dimensional printed buildings have shown that a well-developed automated technology can foster valuable benefits, such as a freeform architectural design without formworks and reduced human intervention. However, scalability, commercialization and sustainability of the 3DPC technology remain critical issues. The current work presents the ecological fragility, challenges and opportunities inherent in decreasing the 3DCP environmental footprint at a material level (cementitious materials and aggregates). The very demanding performance of printable mixtures, namely in a fresh state, requires high dosages of cement and supplementary cementitious materials (SCM). Besides the heavy carbon footprint of cement production, the standard SCM availability might be an issue, especially in the longer term. One exciting option to decrease the embodied CO2 of 3DCP is, for example, to incorporate alternative and locally available SCM as partial cement replacements. Those alternative SCM can be wastes or by-products from industries or agriculture, with no added value. Moreover, the partial replacement of natural aggregate can also bring advantages for natural resource preservation. This work has highlighted the enormous potential of 3DCP to contribute to reducing the dependence on Portland cement and to manage the current colossal wastes and by-products with no added value, shifting to a Circular Economy. Though LCA analysis, mixture design revealed a critical parameter in the environmental impact of 3DCP elements or buildings. Even though cement significantly affects the LCA of 3DCP, it is crucial to achieving adequate fresh properties and rheology. From the literature survey, mixtures formulated with alternative SCM (wastes or by-products) are still restricted to rice husk ash, Municipal Solid Waste ashes and recycled powder from construction and demolition wastes. Natural aggregate replacement research has been focused on recycled fine sand, mine tailing, copper tailing, iron tailing, ornamental stone waste, recycled glass, crumb rubber, rubber powder and granules, recycled PET bottles and steel slag. However, flowability loss and mechanical strength decrease are still critical. Research efforts are needed to find low-carbon cement replacements and mix-design optimization, leading to a more sustainable and circular 3DCP while ensuring the final product performance.

Barriers to Adopting Digital Technologies to Implement Circular Economy Practices in the Construction Industry: A Systematic Literature Review

“…Involvement of fragmented parties: Researchers argued that the enormous number and dispersed nature of stakeholders involved in the construction industry are obstacles to improving construction industry practices [18,19,23,26]. The industry's split structure cre-ates fragmentation among stakeholders at various project stages, increasing the likelihood of errors and poor interaction among these stakeholders, directly hindering the adoption of DT-enabled CE within the industry.…”

“…Furthermore, utilising spatial reversibility (leasing, renting, and renovating) in construction could be challenging even though they are incredibly beneficial circular strategies [4]. Thus, the construction sector faces new obstacles to boosting productivity by adhering to more sustainable, circular, and technologically sophisticated principles [19]. Furthermore, the increasing complexity of projects and project-based organisations in the construction industry concerning the number of stakeholders and establishments, technological or digital domain-specific prerequisites, supply chains and production processes, service outsourcing, and policy regulations have brought platforms (digital ecosystems) to the forefront as comprehensive solutions for cooperation and joint added value generation [20].…”

“…Digital technologies are revolutionising the value of co-creation and collaboration beyond historical industry boundaries, with the potential to significantly impact the construction industry's ability to realise the importance of applying circular economy principles [2][3][4]6,9,14,16,[18][19][20][21][22][23][24]. Advanced digital tools are being implemented across industries, owing to the boost given by the fourth industrial revolution [4].…”

“…However, integrating DTs that help transition to CE is challenging for construction companies and other vital stakeholders [1]. Switching from a linear to a circular flow for materials and components will require significant contributions from various stakeholders [16,19]. Furthermore, ref.…”

“…Significant technological developments have recently opened the chance for the construction industry to invest in state-of-the-art technologies [25]. Thus, the construction sector is undergoing a gradual yet continuous transformation to adopt novel technologies like artificial intelligence (AI), digital twins, BIM (building information modelling), material passport (MP), IoT (internet of things), digital market place (DMP), big data analytics, blockchain [3,4,9,12,14,21,24,26], radio frequency identification (RFID) [2,24], 3D printing [4,19], cloud computing and augmented and virtual reality [4], object detection and computer vision [9] and geographic information system (GIS), and modelling and simula-tion [24] to commit to the built environments' circularity, efficiency, productivity, precision, and safety. As a result, to facilitate this digital transformation, enormous amounts of data are generated, and systematic data analysis and predictive modelling can be used to produce creative structural and architectural designs, increase construction speeds, improve payback periods, lower construction and operational costs, and reduce embodied and operational energy requirements [21].…”