Table 2 Fresh and hardened state... | Emerald Publishing

Table 2

Fresh and hardened state requirements for 3D printable materials

	Property	Definition
Fresh State	Flowability/Pumpability	Capacity of the material to be smoothly transported from the mixer to the printing nozzle; it is affected by temperature and relative humidity
	Extrudability	Capacity of the material to continuously pass through the small pipes and nozzles at the printing nozzle without clogging up the system or interrupting the filament
	Buildability/Shape Retention	Capacity of the material to retain its extruded shape and resistance throughout early ages, under self-weight and under the pressure from upper layers, without excessive deformation; it is possible by using high content of fine aggregates and sand
	Open Time	Time interval in which the fresh material maintains a consistent flow rate for good extrudability (related to the change of flowability with time); the use of appropriate retarders can help controlling the open time
Hardened State	Interlayer Adhesion	The bond between two adjacent layers must be high to improve the structural integrity of the piece
	Drying Shrinkage	Due to the inexistence of formwork, the surface area that contacts with the air is considerable, allowing a high rate of water evaporation and accelerating drying shrinkage; this phenomenon highly increases the risk of cracking
	Mechanical Strength	Compressive strength (usually tested at the ages of 3, 14 and 28 days), flexural strength (usually tested at the age of 7 days) and tensile bond strength between layers
	Printability	When the material reaches all the desirable fresh and hardened properties, a suitable 3D printable material is achieved

	Property	Definition
Fresh State	Flowability/Pumpability	Capacity of the material to be smoothly transported from the mixer to the printing nozzle; it is affected by temperature and relative humidity
	Extrudability	Capacity of the material to continuously pass through the small pipes and nozzles at the printing nozzle without clogging up the system or interrupting the filament
	Buildability/Shape Retention	Capacity of the material to retain its extruded shape and resistance throughout early ages, under self-weight and under the pressure from upper layers, without excessive deformation; it is possible by using high content of fine aggregates and sand
	Open Time	Time interval in which the fresh material maintains a consistent flow rate for good extrudability (related to the change of flowability with time); the use of appropriate retarders can help controlling the open time
Hardened State	Interlayer Adhesion	The bond between two adjacent layers must be high to improve the structural integrity of the piece
	Drying Shrinkage	Due to the inexistence of formwork, the surface area that contacts with the air is considerable, allowing a high rate of water evaporation and accelerating drying shrinkage; this phenomenon highly increases the risk of cracking
	Mechanical Strength	Compressive strength (usually tested at the ages of 3, 14 and 28 days), flexural strength (usually tested at the age of 7 days) and tensile bond strength between layers
	Printability	When the material reaches all the desirable fresh and hardened properties, a suitable 3D printable material is achieved

Source(s): Adapted from Lim et al. (2012), Ma et al. (2017), Ma et al. (2018), Le et al. (2012a), Buswell et al. (2018), Li et al. (2020)