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National greenhouse gas emissions reporting frameworks take a territorial perspective, reporting on emissions produced within national territories. However, much of what we design, engineer and consume in the UK and Europe is manufactured abroad. This 'embodied carbon' is not included in national accounts, nor design and engineering processes, and so is traditionally ignored. There is therefore a significant risk that when taking actions to reduce emissions close to home, we inadvertently increase them elsewhere.To avoid this, designers and engineers must take a full 'carbon footprint' perspective, using life cycle assessment (LCA) or related methods. This presentation will cover the cutting edge in applying LCA in design and engineering, covering a range of collaborative research between academia and industry. It will illustrate the importance of taking a life cycle approach, as well as how it can be done effectively in practice.

The construction industry has traditionally operatedwith linear economy principals, with buildings being demolishedrather than recycled following the end of thedesign life. The industry can play a major role in reducingrequirements for valuable natural resources and promotingsustainable design and construction by adopting practicesadhering to circular economy principals. Central to thiswould be the use of renewable bio-based construction materialsand designing buildings for disassembly - with abuildings’ elements and connecting components designedto be reused, rearranged in a different configuration orrecycled following the expiration of the buildings’ initialfunctional use.

3D printing (or ‘additive manufacturing’ (AM)) systems used to manufacture cementitious structures, either in-situ or off site, utilise specialist formulations. This paper describes a new cementitious formulation which can be extruded from a syringe device without the requirement for the addition of an accelerator at the nozzle. This miniature approach brings advantages in that the system required is smaller, lighter, consumes less power and is suitable for mounting on robots which are not reliant on external power or material supplies. Applications of this smaller scale system include concrete crack repair in hard to access areas and printing of specialist conductive formulations which can be used for sensing. Cementitious pastes were successfully printed using a miniature deposition device which could be carried by a small robotic printing agent. Appropriate workability and buildability following deposition was achieved through the use of cellulose gum additions to the mix formulation. Analysis and characterisation tests carried out on fresh mixes enabled comparison of a 1:1 mix of aluminium lactate and diethanolamine with the commercially available accelerator Master X-Seed, and mixes with no accelerating admixture added. When compared to results featuring no accelerating agent, tests demonstrated that Master X-Seed was the more effective accelerator, promoting early compressive and flexural strength development, but neither accelerator made a constructive contribution to required rheological properties. Master X-Seed was the more effective accelerator, but rheology results suggest the difference occurs logistically too soon for a miniaturised deposition system. The retardation effect of cellulose gum and the potential role of in-situ and off-site miniaturised AM methods are evaluated.

WHITE PAPER: Five Essentials For Successful Circular Bio-Based Construction Initiatives This first publication of the CBCI project (Circular Bio-based Construction Industry) is a practical guide aimed at real estate professionals, (public) property owners and developers. This White Paper will discuss some of the challenges surrounding bio-based and circularity such as; price competition from virgin material alternatives, confidence in quality, hazardous material substance (when reusing in a circular context), lack of existing building data as well as the time delay between building and deconstruction. Next to this, the White Paper aims to illustrate how one could be more successful at taking circular and bio-based construction initiatives. The learnings from interviews and desk research are put together in five essentials, which are explained and illustrated by insights, exemplary projects (case studies) and readily applicable solutions. These five essentials form the outline of this White Paper: 1. AFFORDABLE cost-effective & inclusive reuse, 2. FLEXIBLE prepare for future functions, 3. PASSIVE stay cool & healthy with bio-based materials, 4. INTEGRAL continuously reflect on circular bio-based benefits & 5. TRADITIONAL OWNERSHIP keep it, simple. The thirteen exemplary cases explored for the creation of this White Paper show that it is possible to adopt circular and bio-based construction initiatives. However, it is not always easy and requires perseverance as well as leadership. Therefore, the five essentials and cases in this white paper can be used as inspiration and could help real estate professionals, property owners, developers and other interested parties in the construction sector to realise affordable and feasible circular bio-based constructions. By focusing on the essentials, one could prevent valuable resources (including energy) going to waste, today and in the future.

This first publication of the CBCI project (Circular Bio-based Construction Industry) is a practical guide aimed at real estate professionals, (public) property owners and developers. This White Paper will discuss some of the challenges surrounding bio-based and circularity such as; price competition from virgin material alternatives, confidence in quality, hazardous material substance (when reusing in a circular context), lack of existing building data as well as the time delay between building and deconstruction. Next to this, the White Paper aims to illustrate how one could be more successful at taking circular and bio-based construction initiatives. The learnings from interviews and desk research are put together in five essentials, which are explained and illustrated by insights, exemplary projects (case studies) and readily applicable solutions. These five essentials form the outline of this White Paper: 1. AFFORDABLE cost-effective & inclusive reuse, 2. FLEXIBLE prepare for future functions, 3. PASSIVE stay cool & healthy with bio-based materials, 4. INTEGRAL continuously reflect on circular bio-based benefits & 5. TRADITIONAL OWNERSHIP keep it, simple. The thirteen exemplary cases explored for the creation of this White Paper show that it is possible to adopt circular and bio-based construction initiatives. However, it is not always easy and requires perseverance as well as leadership. Therefore, the five essentials and cases in this white paper can be used as inspiration and could help real estate professionals, property owners, developers and other interested parties in the construction sector to realise affordable and feasible circular bio-based constructions. By focusing on the essentials, one could prevent valuable resources (including energy) going to waste, today and in the future.

Non-residential circular construction projects using bio-based materials have been realised in the United Kingdom. Case studies include the Adnams Distribution Centre, the University of East Anglia’s Enterprise Centre and the British Science Museum’s hempcrete storage facility. The bio-based buildings utilise the natural properties of bio-based materials to insulate and regulate internal environments, particularly with reducing fluctuations in temperature and relative humidity, which can be harmful to sensitive stored products and artefacts. Projects have been successful on both on environmental and physical performance levels; however, they have not led to a subsequent proliferation of non-residential large-scale circular projects within the UK using emerging bio-based materials. This study examines why and uses analysis based upon exclusive interviews with key figures associated with bio-based case studies. Challenges faced include the ability to upscale production by manufacturers of bio-based materials, problems surrounding initial costs, gaining accreditation for materials, the vested interests present in the construction industry and levels of knowledge among clients and construction professionals. Potential upscaling solutions identified include long-term financial savings on running costs and high staff productivity, policies regarding grants, incentives and planning applications and local economic regeneration.

The fused deposition principal of additive manufacturing (AM) involves the deposition of a material one layer at a time allowing the creation of an object from a 3D digital design. The associated reduction in the amount of waste material produced offers benefits and over the last decade, investigations have been carried out using cementitious materials for AM within the construction industry. Central to the profile of the technology increasing within the industry is the development of a suitable cementitious material which may be deposited without formwork. Research currently consists of ground-based gantry, or robotic arm methods which can be single or multi-agent. This paper presents the development of fibrous cementitious mortars and pastes suitablefor a miniaturised deposition system designed for use in a multi-agent AM approach. Synthetic polyvinyl alcohol (PVA), aramid and kevlar fibres along with natural fibres from the banana plant were investigated to evaluate contributions to the workability, buildability, mechanical strength and failure mechanisms of the cementitious composite material. The addition of fibres to a cementitious matrix results in compressive and flexural strength increases and transforms the method of failure from brittle to ductile. Results suggest PVA and kevlar fibres are suitable for a composite cementitious material with optimised rheology specifically designed for a multi-agent, miniaturised deposition approach for AM.

Additive Manufacturing (AM) in the construction industry is still in a relative state of infancy. Research has focused on heavy, ground based methods, with the building envelope determined by the dimensions of the deposition system. By comparison, the approach of using robots is not geometrically restricted but requires a degree of miniaturisation to the deposition process. Many studies utilise the AM principal of fused deposition modelling (FDM), which creates an object by extruding a suitably viscous material through a nozzle and depositing one layer at a time. Crucial to the development of cementitious materials for additive building manufacturing (ABM) without formwork, is the material possessing both workability and buildability, and appropriately balancing the contrasting requirements of these properties. Cementitious materialsare typically brittle, requiring reinforcement to provide tensile and flexural capabilities. Reinforcing steel bars are not naturally compatible with ABM and chopped fibres are considered as a viable alternative. This paper investigates the development of a fibrous cementitious mortar suitable for use with a miniaturised deposition system based upon the FDM principal. Three types of fibres – polypropylene, alkali-resistant glass and polyvinyl alcohol (PVA) - were investigated to assess suitability for a miniaturised ABM deposition method and contributions to the mechanical strength of a mortar. PVA fibres provided the best buildability and increased flexural strength, with the appropriate quantity contained in mixes being informed by the degree of detrimental impact upon workability.

The use of additive manufacturing in the construction industry is still in a state of infancy. Research into suitable materials for Additive Building Manufacturing ABM) have centred upon polymeric and cementitious materials, with the trade-off between workability and buildability central to material development. This study is investigating both CEM1 based mortars and polyurethane foam to evaluate suitability for use in the construction and repair of buildings. High density polyurethane foam possesses sufficient strength and density to be a viable structural material; however, the fresh properties of the material following mixing of components present a challenge as the material exhibits lateral expansion and excessive deformation prior to curing. Microparticles were added to high density foam to investigate the provision of rigidity during curing, however the particles promoted the foaming reaction, reducing density, strength and structural viability. Mortar mixes under investigation placed the emphasis upon workability and minimisation of constituent segregation, while mindful of the material still needing to possess sufficient buildability in order to prevent excessive deformation of extruded layers while deposited material remains in a fresh state.

This paper describes and evaluates a cementitious paste solution for the first aerial additive building manufacturing system, developed to create and repair civil engineering structures in-situ using materials 3D extrusion-printed by aerial robots. Cementitious pastes without aggregate were created to determine their suitability for a powered deposition device light enough to be carried by an aerial robot. Mixes of varying water/cement ratio and plasticiser content, along with admixtures, were manufactured and the curing of the pastes was monitored using a cone penetrometer. Flexural test specimens were manufactured using the deposition device and moulded compressive test specimens were created by hand. Strengths in excess of 40 MPa (compressive) and 2.74 MPa (flexural) were achieved. The optimal mix for extrudability had a water/cement ratio of 0.33 with 1.5% superplasticiser by weight of cement added. This mix remained workable for an hour without additional chemical retardation. The autonomous deposition device successfully imported and extruded workable cementitious paste, demonstrating the structural and operational feasibility of cementitious pastes for autonomous 3D extrusion-printing using aerial robots.