Thereafter, another free-form construction method called concrete printing was developed Fig. pointed out some limitations of CC regarding its excessive steps, including molding and installing reinforcement. CC is a free-form construction method that constructs concrete buildings through extrusion of cementitious material. The need to automate the construction process arose in the 1990s to effectively manage the use of raw materials and solve problems such as low labor efficiency more than 40% of raw materials are consumed globally in the civil engineering field As a result, a cementitious material AM process called contour crafting (CC) was introduced Fig. Consequently, the application of AM in this field has been rather slow and challenging Whether in the manufacturing process, engineering test, or design process, numerous industries utilize AM and benefit from its advantages In the field of civil engineering, however, the utilization of AM is less effective compared to other engineering fields because of the large-scale of infrastructures being built-such as buildings, bridges, tunnels, harbors, and dams-along with their unique characteristics and the condition of the construction sites. Currently, AM can produce a wide range of materials including metallic, ceramic, polymers, and their combinations in the form of composites With the use of this innovative technology, materials that were previously deemed as non-printable have become printable. This layer-by-layer manufacturing allows for the precise production of complex structures which cannot be made using traditional manufacturing routes. Three-dimensional printing, formally known as additive manufacturing (AM), is a layer-based manufacturing technique that create a 3D solid object from a computer-aided design (CAD) model. 4.2 Application of 3D Printing in the Civil Engineering Field

Ivi 3d printer