## 3 Printing Information Model for Additive Manufacturing of Concrete Structures
### Conceptual Modeling of the Printing Information Model
The _ToolpathData_ class collects parameters used to determine toolpaths and printing strategies using the data from the _SlicingData_ class, from the _ContourLine_ class, and from material properties that impact the manufacturing process (_TemporalBehaviour_ class). The _ControlData_ class refers to data that allows machine control by modifying the _MachineSetting_ class. The _MonitoringData_ class collects data from sensor nodes implemented in the machines that allow monitoring of the _SystemData_ class. _ProcessBoundaryCondition_ refer to boundary conditions that dominate the manufacturing process, including results from simulation models such as process constraints and machine constraints. The process boundary conditions may be used to modify the _ToolpathData_ class and may affect the properties of the material in a hardened state (_HardenedStateProperty_ class). The _Material_ class has a composition relationship with the classes _MaterialSpecification_, _MaterialComposition_, _MaterialProperty_, _MaterialTest_, and _MaterialBoundaryCondition_. The _MaterialSpecification_ class encompasses data resulting from the design of the material. From the material specifications, material compositions (the _MaterialComposition_ class) are defined. In the case of concrete, the material composition refers to the mix design, where changes in the mix design modify the material properties (_MaterialProperty_ class) of concrete, including hardened state, fresh state, and temporal behavior. Material tests, denoted by the _MaterialTest_ class, are used to identify material properties and material boundary conditions (_MaterialBoundaryCondition_ class), which include environment constraints and material constraints. The _Geometry_ class has a composition relationship with the classes _Dimension_, _FeatureParameter_, _CoordinateSystem_, _ContourLine_, and _GeometryBoundaryCondition_. The _Dimension_ class provides dimensional consistency between 3D digital models (i.e., geometric features) and printing systems in terms of dimensions, units, and scaling. Geometric feature parameters are described with the _FeatureParameter_ class, including the classes _Location_, _Orientation_, _Shape_, and _CrossSection_. The locations and orientations of geometric features are described relative to a coordinate system (_CoordinateSystem_ class), allowing the connection of geometric features to compose the geometry of a component. Curves defined by geometric features are represented with the _ContourLine_ class, which stores the curves or polylines generated from slicing and is used as input for toolpath planning to describe profiles for each layer. The geometry boundary conditions (_GeometryBoundaryCondition_ class), including feature constraints and tolerance constraints, are dependent on the material boundary conditions and on the machine constraints, which affect the manufacturability of geometric features. Material-process interactions are described in the UML class diagram as semantic relationships, as highlighted in blue in Figure 4. While planning concrete printing projects, material properties must be used as inputs for toolpath planning, in particular those pertinent to the rheological behavior of concrete that changes over time. Profiles of the material properties may be generated during simulations that allow for the evaluation of the success of the build. Process boundary conditions depend on the material boundary conditions, which impact both process constraints and machine constraints. In particular, process constraints may modify the hardened properties of the materials due to the material anisotropy resulting from the layered build-up and the effect of loads acting upon the layers. For example, dry environments may have detrimental effects on the material properties, diminishing the yield strength developed during curing and constraining the range of optimum process parameters, such as maximum build height. To provide knowledge-based reasoning, the PIM model is formalized into the ontology in the following subsection.