# A Knowledge Graph Framework to Support Life Cycle Assessment for Sustainable Decision-Making
## 4 Case Study: 3D Printing
### Domain Expertise of 3 DP
The use of certain additives, such as accelerators and decelerators, is often dictated by the chosen printing technology, particularly when working with concrete, which requires materials with unique properties [67]. [PERSON] et al. (2019) highlight that the practicality, the setting and hardening times, and the mechanical characteristics of 3D-printed concrete can be significantly improved through the careful selection of materials [68]. Furthermore, it is important to note that not all materials can be produced in-house, resulting in the emergence of numerous specialized material suppliers. Once printing has concluded, the process of **post-processing** initiates. This stage may encompass a variety of activities, such as cleanup tasks [58], the application of color, or treatments aimed at enhancing certain material properties or carrying out other refinement procedures. This phase ultimately culminates in preparing the product for its final application, which can include activities like sales [67] and assembly. Notably, these tasks are exclusively performed by the technician, with no additional personnel involved; hence, all associated actions are characterized as messages intended solely for the technician's awareness. The duty of quality control specialists is to verify that the completed item,created by the technician, adheres to the essential standards and specifications required for its designated function. Concurrently, marketing experts are responsible for positioning the product to correspond with a target demographic [69]. Subsequently, the product will be delivered to the end-user or customer. Regarding the topic of **transport**, some important facts must be mentioned. 3 DP facilitates the use of locally available materials, providing an avenue for significant cost reduction in various applications. An extreme example is extraterrestrial construction, where local dust, such as lunar regolith, can be used. This approach significantly reduces the costs associated with transporting raw materials to locations outside the Earth. The potential savings are substantial, considering the costs of shipping a single brick to the Moon, which could be as high as $2 million [70]. Moreover, 3 DP can enable more efficient distribution networks. Urban centers can be established to coordinate material flows and consolidate expertise. However, raw materials for 3 DP still need to be supplied to these centers [71]. This technology alters the traditional mass production and distribution model, moving toward a localized demand-driven production paradigm. Products can be printed according to specific needs and requirements, reflecting a significant change in the manufacturing and distribution approach. 3 DP also allows the production of objects near or directly by consumers, employing just-in-time printing techniques [72]. Upon reaching the conclusion of the printed component's lifespan, the customer has the choice between discarding the part in a landfill, where it will undergo dismantling, or opting for delivery to a recycling facility, where comprehensive processing will occur. Within the domain of 3D printing, **recycling** encompasses a multitude of intricate procedures, beginning with the critical phase of material characterization and analytical assessment to identify any impurities. This process entails, for example, the evaluation of microstructural characteristics and examining surface integrity in powders to determine levels of oxidation and contamination [73]. This phenomenon can be elucidated within contexts such as analytical laboratories, where the deployment of advanced imaging techniques is prevalent, including the utilization of methods like X-ray tomography imaging for detailed investigation [74]. Further studies underscore the importance of understanding the material for efficient recycling [74; 75]. The subsequent phase encompasses the pretreatment of recycling materials, particularly applicable in industrial processing facilities.