3D printing, also known as additive manufacturing, is a process of creating three-dimensional objects from a digital file by depositing material layer by layer. In the context of civil engineering, 3D printing is used to create a variety of structures, including buildings, bridges, and other infrastructure.
3D-printing is a process for making a
3D object of desired shape and size from the 3D model. This 3D model is
prepared in CAD software or generated from scan data of a specific patent.
Nowadays, 3D
printing is widely used in the world. 3D printing technology increasingly used
for the mass customization, production of any types of open-source designs in
the field of agriculture, in healthcare, automotive industry, and aerospace
industries.
In the concrete industry,
3D concrete printing (3DCP) is a top digital fabrication technology that is
utilized for in-situ construction as well as off-site prefabricated panel
manufacturing. Using a 3D printer, concrete is printed to construct three-dimensional
structures in an additive manufacturing method. Layers of material are
deposited on top of one another during the procedure; extrusion is usually used
to apply mortars made of cement. Using digital model design, 3DCP provides
quick construction with highly stiff cement-based materials.
3D printing, a key
component of 4IR, has significantly impacted the building and construction
sector. It promotes the use of eco-friendly materials, enhancing resource
efficiency and environmental protection. The process involves layering
materials, printing them using a designated printer, and creating a specific
model. 3DCP technology offers high efficiency, low labor requirements, and is
environmentally friendly. It also allows for quicker construction, with a
complete building built in just a few days, compared to traditional methods
that can take months or years.
Research on 3D printing
materials based on cement aims to enhance their mechanical properties and
workability. Extrusion parameters, such as nozzle shape, layer height, nozzle
direction, and scraper, play a crucial role in enhancing the performance of 3D
cement-based printing. The shape of the nozzle can affect the mechanical
properties of 3D-printed concrete, with a rectangular nozzle resulting in a
smoother surface for filament. Layer height should not exceed the nozzle width
for adequate interlayer bonding. However, the influence of nozzle direction and
scrapers on 3D cement-based printing characteristics is still limited.
3D-printed concrete
components, produced through layer-by-layer accumulation, have characteristics
similar to anisotropic materials, leading to poor bonding between adjacent
layers. Ensuring the strength of the bond between layers is crucial for the
mechanical properties of printed components. Factors influencing bond strength
include the material's rheology, the performance of the pumping system, the
printing speed, and the shape of the nozzle. The bonding between layers in
3D-printed concrete can also be influenced by the characteristics of the
concrete mixture, such as cement type, particle size distribution, and
water-to-cement ratio. The operation of a 3D printer depends on the thickness
of each layer printed, the rate of printing, and the specific type, shape,
size, and orientation of the nozzle.
Types of 3D printing process
1. Stereolithography (SL)
Materials: Continuous filaments of thermoplastic polymers, fiber-reinforced continuous polymerics, Cementitious materials
Application: Rapid
prototyping of advanced composite parts and toys, building construction.
Benefits: Reduced cost, increased
speed, easy to use.
Drawbacks: Poor mechanical
properties, confined materials.
2. 2. Fused deposition modelling (FDM)
Materials: Compressed fine powder
components, limited polymerics, metals & alloys.
Application: Medicinal, electronic, aviation and lightweight structures
Benefits: High resolution, good quality.
Drawbacks: Prints slowly, expensive cost, high porosity
3. 3. Powder bed fusion (PBF)
Materials: Polymer, metal-filled tapes, ceramics, metal rolls and composites.
Application: Paper
making, foundry sector, smart structures.
Benefits: Reduced tooling,
economical, perfect for generating larger systems.
Drawbacks: Low consistency of the
surface and dimensional precision, manufacturing restriction of complicated
forms.
4. 4 Selective laser sintering (SLS)
Materials: Alloys and metals in the
form of wire or powder, polymers and ceramics
Application: Aerospace,
retrofitting, repair, cladding, biomedical.
Benefits: Low cost and time, good
mechanical properties, accurate regulation of composition, outstanding for
repair
Drawbacks: Low accuracy, poor
surface finish, limitation for complex printing with fine details & shapes.
5.5. Binder jetting (BJ)
Materials: A photo-active resin monomers, polymer- ceramics hybrid.
Application: Biomedical
models
Benefits: High resolution,
premium-quality results.
Drawbacks: Very few materials,
prints slowly, expensive costs
6.6. Direct energy deposition (DED)
Materials: Nylon, thermoplastic, flame retardant nylon.
Application: Electronics,
packaging, connectors.
Benefits: Durable functional parts
with high complex geometries
Drawbacks: Thermal distortion,
rough surface, shrinking, and warping of fabricated parts.
7.7. Laminated object manufacturing (LOM):
Materials: Metals, sand and ceramics that
are granular in shape.
Application: Fabrication
of full-color prototype and wide sand-casting cores and moulds.
Benefits: Low-cost, quick, simple
and cheap.
Drawbacks: Low density, shrinkage
without infiltration.