This paper presents the hardened properties of a high-performance fibre-reinforced fine-aggregate concrete extruded through a 9mm diameter nozzle to build layer-by-layer structural components in a ...printing process. The printing process is a digitally controlled additive method capable of manufacturing architectural and structural components without formwork, unlike conventional concrete construction methods. The effects of the layering process on density, compressive strength, flexural strength, tensile bond strength and drying shrinkage are presented together with the implication for mix proportions. A control concrete (mould-cast specimens) had a density of approximately 2250kg/m3, high strength (107MPa in compression, 11MPa in flexure) and 3MPa in direct tension, together with a relatively low drying shrinkage of 175μm (cured in water) and 855μm (cured in a chamber at 20°C and 60% relative humidity) at 184days. In contrast well printed concrete had a density of 2350kg/m3, compressive strength of 75–102MPa, flexural strength of 6–17MPa depending on testing direction, and tensile bond strength between layers varying from 2.3 to 0.7MPa, reducing as the printing time gap between layers increased. The well printed concrete had significantly fewer voids greater than 0.2mm diameter (1.0%) when compared with the mould-cast control (3.8%), whilst samples of poorly printed material had more voids (4.8%) mainly formed in the interstices between filaments. The additive extrusion process was thus shown to retain the intrinsic high performance of the material.
This paper presents the experimental results concerning the mix design and fresh properties of a high-performance fibre-reinforced fine-aggregate concrete for printing concrete. This concrete has ...been designed to be extruded through a nozzle to build layer-by-layer structural components. The printing process is a novel digitally controlled additive manufacturing method which can build architectural and structural components without formwork, unlike conventional concrete construction methods. The most critical fresh properties are shown to be extrudability and buildability, which have mutual relationships with workability and open time. These properties are significantly influenced by the mix proportions and the presence of superplasticiser, retarder, accelerator and polypropylene fibres. An optimum mix is identified and validated by the full-scale manufacture of a bench component.
Additive manufacturing in construction is beginning to move from an architect's modelling tool to delivering full-scale architectural components and elements of buildings such as walls and facades. ...This paper discusses large-scale additive manufacturing processes that have been applied in the construction and architecture arena and focuses on ‘Concrete Printing’, an automated extrusion based process. The wet properties of the material are critical to the success of manufacture and a number of new criteria have been developed to classify these process specific parameters. These criteria are introduced and key challenges that face construction scale additive manufacturing are presented.
► Built a full-scale of extrusion-based additive manufacturing (AM) machine for Freeform Construction. ► Developed a high performance concrete for Concrete Printing process. ► Created a variety of prototype parts, including the world's first reinforced concrete AM component — WonderBench.
Construction is a heavy manual industry where working into later life can be a challenge. An interview study was conducted to explore workers' understanding of their health at work and ways of making ...their jobs easier, safer or more comfortable. Using purposive sampling, 80 trades’ workers were selected from construction sites in the UK. The Nordic Musculoskeletal Questionnaire and Work Ability Index were used to explore aches and pains and reducing strain on the body. A high prevalence of symptoms was reported and ratings of work ability were high. Workers were aware of the physical demands of their work and had over 250 ideas around health and wellbeing e.g. rucksacks for tools, bespoke benches, adapting PPE, and higher cost solutions e.g. mechanical lifting aids. Engagement of the workforce should be encouraged and feed into change processes in the industry to enable all workers stay fit for work for longer.
•Construction workers care about maintaining good health and wellbeing at work.•Construction workers have many good ideas to improve their job and workplace.•It is important that good practice is shared across the industry to facilitate healthy ageing.•Using elements of participatory ergonomics could enable sharing of good practice.
AbstractDespite extensive research into attitudes and practice surrounding the uptake of off-site production technologies, there is limited understanding of how best to integrate their use into ...business processes at the organizational level. Drawing on an action-research case study with a leading U.K. house-building organization, this paper scrutinizes the processes through which off-site technologies were adopted and utilized. The use of off-site methods was fundamentally framed by the key stages and business milestone reviews of the house-building process, which together represented a complex and multilayered structure of business management. Five off-site reviews were aligned with the business processes. Strategies for integrating the use of off-site technologies are examined. It was crucial to establish an overall off-site strategy and integrate it into the process from land acquisition on. Organizational learning embraced the adoption of off-site methods, whereas extra reporting and management efforts introduced bureaucracy. Culture change was commonly perceived as difficult and painful. Earlier engagement with supply chains was advocated for favoring the off-site approach and improving business efficiency, whereas it also demanded greater commitment of the house builder to specific supply chains and therefore exposed the business to risks associated with planning and market changes. The strategies should facilitate building companies’ strategic management of off-site technology.
The utilisation of automation technology and processes control found in the automotive and aerospace industries is not paralleled in modern day construction. The industry also struggles to improve ...health and safety issues and still uses traditional methods of procurement. These problems are compounded by the diminishing skills in the labour force. Methods of production must change if these issues are to be resolved. Rapid Manufacturing is a family of digitally controlled additive processes that have the potential to impact on construction processes. This paper outlines some of the major issues facing construction technology and gives examples of the use of large scale Digital Fabrication in the industry. The term ‘Freeform Construction’ is defined. Potential applications derived from an industrial workshop are presented and results from a series of preliminary studies indicate the viability of mega-scale Rapid Manufacturing for construction.
AbstractA lack of value-based decision criteria leads to an inability to effectively compare prefabrication and off-site production with conventional construction, which inhibits the realization of ...benefits of off-site approaches. This paper develops value-based decision criteria and quantifies their relative importance for assessing building technologies systematically. The research employed a multimethodological strategy within a broad case-study-based design, with six large house-building organizations in the United Kingdom. These companies together accounted for more than one-tenth of new-build home completions in the United Kingdom. More than 50 criteria were developed, grouped under cost, time, quality, health and safety, sustainability, process, procurement, and regulatory and statutory acceptance. Cost was ranked most important, which, coupled with time and quality, predominated technology selection in these companies. Sustainability, process, and procurement were weighted lower, whereas health and safety and regulatory and statutory acceptance were deemed compulsory, hence offering no trade-off opportunity. A lack of incorporating innovative sustainable technology into corporate strategy was observed. The developed criteria and the systematic process should help house-building organizations manage technological innovation and hopefully achieve more informed corporate decisions.
Purpose> Substantial changes were made on many UK construction projects in response to the COVID-19 pandemic. The purpose of this paper is to explore the unanticipated positive consequences of these ...and the scope for longer-term learning and developments within the sector. Design/methodology/approach> A qualitative approach was used, semi-structured interviews were conducted across six major project sites. Interviewees (n = 33) included site and senior managers, supply chain representatives and occupational safety and health (OSH) professionals. The interviews explored their experiences of working on site during the pandemic, the changes made to work practices and their perceived impacts of these changes. Findings> Improved planning and work sequencing were part of the revised process to make sites COVID-secure. This increased worker effectiveness and housekeeping/tidiness. The view on some sites was that this would improve OSH performance. The changes were perceived to be beneficial but may not be accepted by clients in the long term, as they could result in projects taking longer to complete. The ways in which COVID-19 risk has been communicated and perceived also provides longer-term lessons for the sector’s OSH management and training. Originality/value> Construction has adapted rapidly and effectively to new ways of working during the pandemic. This research captured in real time some of the changes made and presents an argument for embedding and adopting the changes to improve working arrangements and OSH within the construction sector.
PurposeDecisions made during the design stage of construction works can significantly reduce the risk of occurrence of occupational accidents, injuries and illnesses. Moreover, it has been ...established that design is one of the major contributors of accidents and injuries. Design for safety (DfS) studies within construction have highlighted factors affecting the implementation of DfS, among which are designer attitude; DfS knowledge/awareness and education; availability of DfS tools, including guidance; client’s influence and motivation; and legislation. The purpose of this study is to carry out an in-depth literature review of DfS studies within construction to explore the extent to which existing DfS research has looked at the above-listed DfS implementation factors.Design/methodology/approachA review of 164 journal articles related to DfS in construction (published from 1990 to 2017) within built environment, engineering and multidisciplinary safety journals was undertaken.FindingsThe findings indicate that around 60 per cent of the journal articles reviewed address designer knowledge/awareness and education issues, about 27 per cent looked at DfS implementation tools to assist designers to undertake DfS, about 23 per cent studied client influence/motivation, about 16 per cent studied designers’ attitudes towards DfS implementation and approximately 16 per cent looked at the role of legislation in DfS implementation. The literature points that client influence/motivation and legislation are very influential DfS implementation factors despite a limited number of studies in these areas.Originality/valueOverall, the findings provide an indication of areas of DfS implementation, particularly client influence/motivation and legislation, where more research would be needed to promote DfS in construction to help mitigate the occurrence of accidents and injuries.
Despite an increasing demand for housing and wider concerns over the need to improve performance, the industry seems to be reluctant to adopt offsite technologies. Many studies have attempted to ...scrutinize the barriers and seek ways forward, but the perspectives of housebuilders remain unclear. UK housebuilders' views on the use of offsite modern methods of construction (offsite MMC) have been investigated. This investigation was carried out through a combination of personal interviews and a questionnaire survey of the top 100 housebuilders by unit completion. Results suggest that the traditional drivers of time, cost, quality and productivity are still driving the industry in deciding whether to use offsite technologies. Nearly two-thirds of the firms believed that there needs to be an increase in the take-up of such technologies. However, current barriers relate to a perceived higher capital cost, complex interfacing, long lead-in time and delayed planning process. Strategies recommended are centred on changing peoples' perceptions, improving procurement, providing better cost data, tackling planning and regulations, encouraging political levers and providing practical guidance. The suggestions present a model for encouraging the take-up of offsite MMC in the future.
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