Composite alkali-activated materials with waste tire rubber designed for additive manufacturing: an eco-sustainable and energy saving approach

Copyright © 2023 The Author(s). There is an increasing trend in research projects and case studies to demonstrate the potential of Additive Manufacturing (AM) with concrete, better known as 3D concrete printing. Like ordinary construction, the latest upgrades on this topic are strongly focused towards improving eco-sustainability in terms of low-carbon materials. Low-carbon binders’ alternative to Portland cement and the utilisation of selected waste materials in place to virgin aggregates has high potential in fulfilling the sustainable development goals. In this paper, an experimental study was performed by incorporating ground waste tire rubber aggregates of different size gradation (0–1 mm and 1–3 mm) and replacement levels (50 v/v% and 100 v/v%) in a “greener” alkali-activated mix designed for 3D printing applications. First, the experimental program involved the optimization of mix design rheology and printing parameters to successfully integrate rubber aggregates into the printable alkali-activated mixtures. Then, a comprehensive characterization, including static mechanical testing, dynamic thermo-mechanical analysis, thermal conductivity testing, and acoustic insulation measurements was conducted. Comparison with identical Portland-based rubberized formulations designed for AM revealed better mechanical isotropy, flexural strength, thermo-mechanical behaviour, heat insulation, and high-frequency acoustic insulation for alkali-activated composites. The influence of rubber aggregate size on the fresh and hardened state behaviour of the mixes was also studied and discussed. Keeping the losses in mechanical strength restrained, the rubberized composites designed in this study have demonstrated significant thermal and acoustic insulation properties that are desired for energy-saving applications in buildings. The research verified the practicability of using waste aggregates in low-carbon binders for sustainable lightweight and thermo-acoustically effective applications, establishing an attractive starting point to address future research on material optimization for practical purposes

Graphene-based nano-functional materials for surface modification of wheat straw to enhance the performance of bio-based polylactic acid composites

Data availability: Data will be made available on request.Copyright © 2022 The Author(s). To enhance wheat straw compatibility with the polylactic acid (PLA) matrix, several graphene-based materials (GBMs) derivatives, including graphene nanoplatelets, graphene oxide, and nano graphite particles with a constant fraction of 0.1 wt.-%, were employed for the surface functionalisation of wheat straw. Wheat straw surface quality was assessed by comparing PLA bio-based composites' mechanical and thermal performance with and without GBM surface functionalisation. All the resulting composites with surface functionalised straw particles exhibited higher thermal stability, flexural strength, tensile strength, and tensile toughness than those with pristine straw. This could be associated with the improved straw/PLA matrix interfacial bonding induced by the existence of GBMs on the surface of straw particles which was confirmed through morphology assessments. The mechanical properties investigations revealed maximum enhancements of 27%, 66%, and 322% for flexural strength, tensile strength, and tensile toughness, respectively, for bio-based composites consisting of graphene oxide-functionalised straw particles compared to control samples.This work was funded as part of the HP-CSB project, which has received funding from the Engineering and Physical Sciences Research Council with the following reference: EP/S026487/1. The authors acknowledge Nanesa S. r.l for graphene material supply

Additive Manufacturing and the Construction Industry

Copyright © 2023 The Author(s). Additive manufacturing (AM), including 3D printing, has the potential to transform the construction industry. AM allows the construction industry to use complex and innovative geometries to build an object, building block, wall, or frame from a computer model. As such, it has potential opportunities for the construction industry and specific applications in the deep renovation process. While AM can provide significant benefits in the deep renovation process, it is not without its own environmental footprint and barriers. In this chapter, AM is defined, and the main materials used within the construction industry are outlined. This chapter also explores the benefits and challenges of implementing AM within the construction industry before concluding with a discussion of the future areas of development for AM in construction.Brunel University London BRIEF award: Additive Manufacturing Technology in Construction (AMTC); 10.3030/101029471 European Union’s Horizon 2020 Research and Innovation Programme (H2020-EU) under grant: Digital fabrication and integration of Material reuse for environmentally friendly cementitious composite building blocks; European Union’s Horizon 2020 Research and Innovation Programme through the RINNO project (https://rinno-h2020.eu/) under Grant Agreement 892071, and the Irish Institute of Digital Business

Enhanced Compatibility of Secondary Waste Carbon Fibers through Surface Activation via Nanoceramic Coating in Fiber-Reinforced Cement Mortars

Data Availability Statement: Data will be made available on request.Copyright © 2023 by the authors. The utilization of waste fibers in the production of reinforced concrete materials offers several advantages, including reducing environmental strain and socio-economic impacts associated with composite waste, as well as enhancing material performance. This study focuses on the development of cementitious mortars using secondary waste carbon fibers, which are by-products derived from the industrial conversion of recycled fibers into woven/non-woven fabrics. The research primarily addresses the challenge of achieving adequate dispersion of these recycled fibers within the matrix due to their agglomerate-like structure. To address this issue, a deagglomeration treatment employing nanoclay conditioning was developed. The functionalization with nanoclay aimed to promote a more uniform distribution of the reinforcement and enhance compatibility with the cementitious matrix. Various fiber weight percentages (ranging from 0.5 w/w% to 1 w/w% relative to the cement binder) were incorporated into the fiber-reinforced mix designs, both with and without nanoceramic treatment. The influence of the reinforcing fibers and the compatibility effects of nanoclay were investigated through a comprehensive experimental analysis that included mechanical characterization and microstructural investigation. The effectiveness of the nanoceramic conditioning was confirmed by a significant increase in flexural strength performance for the sample incorporating 0.75 w/w% of waste fibers, surpassing 76% compared to the control material and exceeding 100% compared to the fiber-reinforced mortar incorporating unconditioned carbon fibers. Furthermore, the addition of nanoclay-conditioned carbon fibers positively impacted compression strength performance (+13% as the maximum strength increment for the mortar with 0.75 w/w% of secondary waste carbon fibers) and microstructural characteristics of the samples. However, further investigation is required to address challenges related to the engineering properties of these cementitious composites, particularly with respect to impact resistance and durability properties.This research was supported by the “Avvio alla Ricerca—Tipo 2” funding program provided by Sapienza University of Rome to Dr. Matteo Sambucci. The title of the research project is: Compositi sandwich a matrice cementizia: ottimizzazione delle caratteristiche meccaniche e di isolamento termo-acustico attraverso l’uso di materiali di riciclo derivanti dal recupero di pneumatici a fine vita (no. AR222181627BFECA)

Wheat straw pre-treatments using eco-friendly strategies for enhancing the tensile properties of bio-based polylactic acid composites

Engineering and Physical Sciences Research Council HPCSB project: EP/S026487/1

Hot gas forming of aluminum alloy tubes using flame heating

Hot metal gas forming (HMGF) is a desirable way for the automotive industry to produce complex metallic parts with poor formability, such as aluminum alloys. A simple hot gas forming method was developed to form aluminum alloy tubes using flame heating. An aluminum alloy tube was heated by a flame torch while the tube was rotated and compressed using a lathe machine and simultaneously pressurized with a constant air pressure. The effects of the internal pressure and axial feeding on expansion and wall thickness distribution were examined. The results showed that the proposed gas forming method was effective for forming aluminum alloy tubes. It was also indicated that axial feeding is a vital parameter to prevent reductions in wall thickness by supplying the material flow during the forming process.This research received no external funding

Understanding the challenges of construction demolition waste management towards circular construction: Kuwait Stakeholder’s perspective

Data Availability: Data will be made available on request.Copyright © The Authors 2023 . The built environment sector is under increasing pressure to reduce costs while improving environmental quality. This paper examines Kuwait’s current construction and demolition waste (CDW) management policy, highlights the obstacles faced by recycling processes and suggests solutions to enhance waste management practices. Kuwait has only one landfill dedicated exclusively to CDW, operating since 2009. Even though Kuwait has facilities dedicated to handling and recycling CDW, recycling faces several obstacles that hinder its efficacy. This study aims to identify the impediments to efficient management practices through an extensive review of the literature followed by a questionnaire that was sent to 42 relevant stakeholders and interviews conducted with five stakeholders from the 1) Municipality of Kuwait, 2) the Ministry of Public Works, 3) the Environmental Public Authority, 4) the Kuwait Institute for Scientific Research, and 5) the Environment Preservation Industrial Company. This study concluded that present waste management procedures are inappropriate for achieving the circular construction concept and the 4 R framework (reduce, reuse, recycle and recover). Furthermore, it was found that raising the awareness of construction stakeholders and the public about waste management and recycling benefits is essential. This can be successfully implemented by emphasising recyclable products' economic and financial benefits. There is also a need to enforce Kuwait’s existing environmental legislation and regulations to achieve a better CDW control framework. The outcomes of this study will assist decision-makers in establishing strategies to address the barriers to circular waste management practices in Kuwait and beyond

Processes and materials used for direct writing technologies: A review

Corrigendum to “Processes and materials used for direct writing technologies: A review” [Results in Engineering (2021) 11, 100257], 17 November 2021, 100308: ☆ The authors regret there is an update to Acknowledgments: This work was funded as part of the DiWoCiS project, which has received funding from the Katip Çelebi-Newton Fund Institutional Links Grants of The Scientific and Technological Research Council of Turkey and British Council. ☆☆ The authors would like to apologise for any inconvenience caused.Direct Writing (DW), also known as Robocasting, is an extrusion-based layer-by-layer manufacturing technique suitable for manufacturing complex geometries. Different types of materials such as metals, composites, ceramics, biomaterials, and shape memory alloys can be used for DW. The simplicity and cost-efficiency of DW makes it convenient for different applications, from biomedical to optics. Recent studies on DW show a tendency towards the development of new materials and applications. This represents the necessity of a deep understanding of the principles and parameters of each technique, material, and process challenge. This review highlights the principles of many DW techniques, the recent advancements in material development, applications, process parameters, and challenges in each DW process. Since the quality of the printed parts by DW highly depend on the material extrusion, the focus of this review is mainly on the ceramic extrusion process and its challenges from rheological and material development point of view. This review delivers an insight into DW processes and the challenges to overcome for development of new materials and applications. The main objective of the review is to deliver necessary information for non-specialist and interdisciplinary researchers.Newton Fund Institutional Links Grants - British Counci

A review of 3D printing low-carbon concrete with one-part geopolymer: Engineering, environmental and economic feasibility

Data Availability: Data will be made available on request.Copyright The Author(s) © 2022. 3D printing is a developing technology that has the ability to use different materials to produce concrete elements with complex shapes. The utilization of geopolymers or alkali-activated materials (AAMs) in 3D printing is receiving significant interest due to the environmental benefits of replacing ordinary Portland cement (OPC). The use of solid activators to produce a one-part geopolymer can help the broader use of geopolymers at large scales, as the corrosive, viscous, and hazardous liquid activators used in two-part geopolymers do not present a feasible large-scale solution for this technology. This paper reviews the 3D printable one-part geopolymers, their compositions, and the effect of different precursor compositions, activator content, and different admixtures on the fresh and hardened properties of the mixtures. The environmental impact and cost assessment of one-part geopolymers produced by conventional and 3D printing methods are also discussed and compared to OPC and two-part geopolymers. This review concluded that one-part geopolymers are easier to mix and use than two-part geopolymers and have a lower carbon footprint than two-part geopolymers and OPC concrete. However, one-part geopolymers may not be as strong as two-part geopolymers, but they are still better than OPC.Part of the DigiMat project, which has received funding from the European Union's Horizon 2020 research and innovation program under the Marie Skłodowska-Curie grant agreement ID: 101029471