Researchers from the University of Tehran have developed a new concrete that can be 3D printed into houses in a way that generates 400 times less CO2 emissions than current constructions.
In a simulated 3D print of a house, the team found that using a reactive magnesium oxide mixed with thermal insulation and phase change materials (PCM) both reduced its energy consumption energy and its environmental impact. If rolled out on a larger scale, engineers say the material could help make 3D printing a more attractive tool to tackle both the housing shortage and the problem of climate change.
Clean up the construction sector
According to a study by the European Commission, conventionally constructed buildings account for 36% of all CO2 emissions generated in the EU. Of course, due to the increase in population, building affordable housing is a necessity, but building it in a more sustainable way is quickly becoming a hot research topic. These studies have often focused on reducing the cooling and heating loads of buildings.
This is seen as crucial to improving the sustainability of the house building process, as it could help reduce the fuel requirements associated with building and heating them. Previous research has shown that one way to improve the thermal performance of these buildings is to 3D print them from PCM, which can absorb heat in a specific range and manage internal temperatures.
However, the Tehran team says these PCMs have proven ability to “improve heat capacity”, but their mechanical properties may decline, hampering their end-use potential. Engineers also say that other materials, in which networks of geopolymers are infused into cement, have a mixed level of environmental success, with some still having a high CO2 footprint.
More durable 3D printing cement
To identify the optimal cement formula for 3D printing, the team studied the performance of simulated constructions made with cements based on magnesium oxide (RMC) and calcium sulfoaluminate (CSA). Through testing through DesignBuilder software, both were found to be able to set quickly and showed high initial strength levels, but RMC had a higher compressive strength of 60 MPa.
When it came to analyzing the durability of this two-story virtual construction, the researchers opted to subject it to a complete life cycle assessment (LCA), from shipping to materials and energy consumption. electricity. It turned out that the LCA results showed that their two cement formulations had a lower ecological impact than conventional Portland cement, with CSA’s energy consumption being higher than RMC’s.
To make their materials more efficient at managing internal temperatures, the engineers then added calcium chloride to the mixtures. Adding the compound allowed mixtures to be 3D printed in concrete capable of absorbing and discharging heat when they reach a melting or freezing point. Supplementing RMC with foam in the simulations also enhanced this effect, optimizing building insulation.
Ultimately, the presence of magnesium was found to add to the carcinogenic toxicity of the house walls, but the 3D printed RMC with insulation had the least ecological impact. As a result, the team concluded that 3D printing can “go a long way towards reducing the energy consumption” of the build in the future, even though their RMC is still quite water-intensive and has toxicity issues that need to be addressed. be resolved.
The potential of AM in self-cooling buildings
Significant research is underway to optimize the thermal efficiency of 3D printed concrete constructions, especially in the field of building materials. Researchers at Texas A&M University, for example, have developed 3D-printed phase-change materials that can be used to build homes capable of passive internal temperature regulation.
In the past, Microlight3D has also received support from the EU to develop concrete to create “self-cooling” buildings. Working with five European universities as part of the Future and Emerging Technologies (FET) program, the company aims to design a microstructured material that combats the urban heat island phenomenon.
Elsewhere, a team from Swinburne University of Technology and Hebei University of Technology has taken a different approach to making home building more environmentally friendly. By developing a 3D printing material made from construction waste, engineers hope to reduce CO2 emissions from additively manufactured buildings and the technology’s reliance on natural resources.
The researchers’ findings are detailed in their paper titled “Thermal performance study and life cycle assessment of a 3D printed buildingwhich was co-written by Mahdi Ebrahimi, Mohammad Mohseni Alireza Aslani and Rahim Zahedi.
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The featured image shows a concrete 3D printer in action. Photo via Hamilton Labs.