Design Life-Cycle

 Isabella Markell

Krishna Das

DES 40A

Professor Cogdell

3D Printed House Materials

The arrival of 3D printed technology has impacted many industries, including construction. The typical construction of houses hasn’t changed much in the last few hundred years. After a floor plan is created, the bones of the house are made with wood, followed by a strengthening agent, either concrete, bricks, or wood panels. This process typically takes a long amount of time and tons of workers perform different duties. The new advanced technology of 3D-printed homes was designed to take less time, energy, and materials, and cost less. 3D printing typically involves pumping a cement mixture through a nozzle to form a structure layer by layer. They also have the ability to easily construct round-shaped walls and advanced designs. Materials are important in the design process for 3D-printed homes because they have to be structurally sound, while also maintaining durability, sustainability, and safety. Understanding the materials used in each stage of the life-cycle of 3D printing houses and buildings is necessary for determining the economic importance, sustainability, and environmental impact of these projects.

The initial stage in the life cycle of 3D-printing buildings is the acquisition of raw materials from the Earth. Mohammad et al. (2020) highlight the types of raw materials used in 3D concrete printing. These include cement, aggregates, and various additives for different effects. Because the primary material of cement is already at the core of the construction industry, using it for this new process means that it is readily available. Cement is made from limestone, which is extracted from quarries through blasting and mining. Aggregates, coarse particulate materials such as sand, gravel, and plain rocks, are also obtained from natural deposits. These additives are combined with cement to strengthen it. While cement is used frequently, there are severe environmental impacts associated with its extraction. According to Mohammad et al. (2020), “concrete production has a large carbon footprint, accounting for 4-5% of worldwide emission of CO2,” which is unfortunate when it is used in a “new and sustainable” way such as 3D printed buildings. Cement quarrying can also cause land degradation, loss of biodiversity, and habitat destruction around the locations of quarries, similar to mining other materials (Hewlett & Liska, 2019). To help avoid these environmental impacts, alternative materials for 3D printing such as recycled concrete aggregate (RCA) can be used instead. Han et al. (2021) discuss how using RCA in 3D printing can reduce the need for mining new aggregates, and reduce construction waste and pollutant emissions. They also found that “the cost of buildings made of recycled concrete decreased as the proportion of recycled aggregate increased, owing to the higher price of natural aggregate.” Using these smart replacements for traditional concrete is a step in the right direction for making 3D-printed homes completely sustainable in the future.

Once the raw materials are extracted from the source, they must be processed and prepared to turn into a printable material. El-Sayegh et al. (2021) provide an overview of these material processing techniques, starting with cement processing. Achieving the correct particle size and consistency is key for the printing materials to run smoothly. Without the right consistency, the cement will not be able to pump out of the nozzle correctly and could use up more energy than it should. To process cement to become a usable mixture, the limestone is first ground up into a fine powder and then mixed with other components. After, it is heated in a kiln to produce an intermediary product known as clinker and is then ground again to form cement (Hewlett & Liska, 2019). The energy and resources needed for this material production is further examined by Roux et al. (2021). In addition to the extraction of materials for cement, the production is also energy-intensive and involves high temperatures with significant fuel consumption. This means that it produces large amounts of CO2 emissions, furthering the impact on climate change. 

As with most products used in manufacturing, the transportation of extraction sites of raw materials to processing plants, and then construction sites uses vehicles that produce negative environmental consequences. Abdalla et al. (2021) examine this environmental footprint and describe how fuel consumption and emissions from the transportation of construction materials contribute to the impact. Because cement materials and aggregates are so heavy, large vehicles are needed to transport them, which in turn need to use more energy. 3D printing can potentially reduce the need for as much transportation because it allows for the production of building components directly on the site of the project. This would minimize the distance that the materials would have to travel and the number of trips to transport all of the materials. The other option is assembling various parts off-site and then transporting them to the site. Having these materials on-site reduces the emissions used in transportation as well as the overall construction time and cost. While this option is the most efficient, the transportation of the 3D printer must be taken into account (El-Sayegh et al., 2020).

The primary use of materials in 3D-printed buildings comes from the printing itself. Ibrahim et al. (2022) go into detail about this process and how it involves layer-by-layer deposition of concrete to form the walls and structural elements of the specific construction. Similar to tabletop 3D printing, construction 3D printing uses 2D designs to form the 3D building. The printer must be carefully calibrated to ensure precision and structural integrity between each layer, which involves software and hardware adjustments by workers on the project. Muñoz et al. (2021) describe an additional form of 3D printed construction known as additive and subtractive processes and how they can work together to form a higher quality and finish in these projects. While there are aesthetic advantages, using subtractive processes requires additional energy and resources. In this context, additive means the production of normal layers of 3D-printed cement, and subtractive means smoothing out the typical “ribbed” nature of these layers before they dry once the process is complete. While some might want to take advantage of this extra process, it decreases the overall energy efficiency and requires more time, which impacts the sustainability of the project. By advancing the technologies of printers in the future, waste can be reduced by precisely controlling the material deposition, resulting in the optimization of the material processes. 

In addition to printing the layers of the walls, traditional construction techniques involving window and door installations are required in the production process (Saleem, 2020). The world’s largest 3D-printed building is located in Dubai and serves as a landmark case study in demonstrating the power of this construction method, and the challenges that are faced. The robotic construction company known as Apis Cor produced this building and currently has plans to expand their designs into building affordable housing in the US states of Florida, Louisiana, and California, as well as designing a habitat for Mars in a NASA competition (India Block, 2019). By using a combination of 3D printing and traditional construction, this has the potential to be the new standard for affordable housing, as companies like Apis Cor continue to put research and effort into these technologies. 

At the end of life for 3D-printed buildings, the materials left over from deconstruction must be recycled or disposed of. 3D-printed buildings are a relatively new technology, so there isn’t much evidence on the specific deconstruction and recycling of the cement used in these buildings (Roux et al,. 2023). However, cement has the potential to be crushed and reused as aggregate in new construction projects (Han et al., 2021). As mentioned in the manufacturing process, using recycled cement reduces the need for virgin materials, which promotes a circular economy and minimizes construction waste. As for the printer waste, there are many components that make up its frame, each with their own life-span. The part life cycles range from 6 months to 20 years, while the buildings are said to last around 50 years (Muñoz et al., 2021). The difference in waste management also depends on the material. Metal components like motors and pumps are sent to be recycled, while plastic components are disposed of in landfills. ​​In addition to waste produced by the printer, during construction, waste must be minimized compared to other construction methods due to the precision of the printing process. The printers are designed to accurately deposit material only in the specified areas (El-Sayegh et al,. 2020). End-of-life buildings can be deconstructed, and their materials can be sorted for recycling, which will reduce waste in the end, and help the environment. 

In conclusion, 3D-printed homes represent how new construction technologies have the ability to evolve to solve various problems relating to cost, time, environmental impacts, and energy usage. The life cycle of 3D-printed buildings include multiple stages that approach environmental and economic impacts differently, but are all important to examine to get a full understanding of this process. By using innovative materials and new processes, 3D-printed buildings offer a largely more sustainable alternative to traditional construction methods. Because this technology is still fairly new, continued research needs to happen in order to optimize the process and further enhance sustainability, especially in its end-of-life. Advancements in research and knowledge will also mainstream this method, allowing for a broader impact on affordable housing, and other use-cases. 

Bibliography

Abdalla, H., Fattah, K. P., Abdallah, M., & Tamimi, A. K. (2021). “Environmental Footprint and Economics of a Full-Scale 3D-Printed House.” Sustainability, 13(21), 11978. doi.org/10.3390/su132111978

El-Sayegh, S., Romdhane, L. & Manjikian, S. “A critical review of 3D printing in construction: benefits, challenges, and risks.” Archiv.Civ.Mech.Eng 20, 34 (2020). doi.org/10.1007/s43452-020-00038-w

Han, Y., Yang, Z., Ding, T., & Xiao, J. (2021). “Environmental and economic assessment on 3D printed buildings with recycled concrete.” Journal of Cleaner Production, 278, 123884. doi.org/10.1016/j.jclepro.2020.123884

Hewlett, Peter C., and Martin Liska, eds. “Lea's Chemistry of Cement and Concrete.” 5th ed., Butterworth-Heinemann, 2019.

Ibrahim, I., Eltarabishi, F., Abdalla, H., & Abdallah, M. (2022). “3D Printing in Sustainable Buildings: Systematic Review and Applications in the United Arab Emirates.” Buildings, 12(10), 1703. doi.org/10.3390/buildings12101703

India Block 22 December 2019 “World’s Largest 3D-Printed Building Completes in Dubai.” Dezeen, 10 Mar. 2021, www.dezeen.com/2019/12/22/apis-cor-worlds-largest-3d-printed-building-dubai/. 

Mohammad, M., Masad, E., & G., S. “3D Concrete Printing Sustainability: A Comparative Life Cycle Assessment of Four Construction Method Scenarios.” Buildings, 10(12), 245, 2020 doi.org/10.3390/buildings10120245

Muñoz, I., Alonso-Madrid, J., Menéndez-Muñiz, M., et al. “Life cycle assessment of integrated additive–subtractive concrete 3D printing.” Int J Adv Manuf Technol 112, 2149–2159 (2021). doi.org/10.1007/s00170-020-06487-0

Roux, C., Kuzmenko, K., Roussel, N. et al. “Life cycle assessment of a concrete 3D printing process.” Int J Life Cycle Assess 28, 1–15 (2023). doi.org/10.1007/s11367-022-02111-3

Saleem, Farah. “World’s Largest 3D-Printed Building in Dubai.” Engineering.Com, 29 Jan. 2020, www.engineering.com/story/worlds-largest-3d-printed-building-in-dubai.