Advancement in 3D-printed concrete promises strength, durability and lower carbon emissions – Science Daily
A new 3D printing method for concrete promises greater strength, durability and lower carbon emissions, a team of researchers reports. The technique involves embedding particles of recycled construction waste in the concrete to make it tougher and reduce the amount of virgin cement used.
The findings were published today in the journal Cement and Concrete Composites.
3D printing, also called additive manufacturing, is gaining popularity in construction as it allows for more complex shapes, design flexibility, and fewer laborers on site. But 3D-printed concrete is often considered weak and brittle, and lacks the strength needed for structural applications. The high energy requirements in making cement, the key component of concrete, also have an outsize impact on the carbon footprint of construction.
The researchers from Arizona State University, ETH Zurich, and Imperial College London combined two innovations: the use of 3D printing and a new type of cement paste made with recycled concrete aggregate. They studied a wide range of mixture ratios and determined that the combination of these innovations produces high-performing concrete with high compressive strength and lower carbon emissions.
“What we see is that this innovative approach can simultaneously provide strong 3D-printed concrete with superior mechanical properties and significantly reduce carbon emissions. We used the method to produce structural elements in our laboratory, including a curved wall. And the 3D printing method itself provides even more design freedom,” says Dr. Kunal Masal, associate professor in the School of Sustainable Engineering and the Built Environment at Arizona State University.
This research investigated the impact of different size ranges of the recycled aggregate on the mechanical performance of the 3D-printed concrete, revealing some of the advantages of using recycled aggregate in the 3D printed material.
“The presence of recycled aggregate influences the overall concrete performance. One of the factors that makes the aggregate beneficial is that it enhances the density of the concrete,” says Masal. “Because of that, 3D-printed concrete samples have a higher density, thus improving the performance.” He also adds, “The second point is that this kind of aggregate enhances the porosity of the material and leads to more interconnected pores, resulting in more homogeneous and better bonded microstructures that eventually improve the material’s strength.”
These improvements lead to reduced brittleness in the concrete material, contributing to its overall strength and resilience. While the recycled aggregates make the material stronger, the study showed that even in these mixes, less cement was needed than traditional concrete. In fact, it achieved high performance and low emissions.
“This novel process is much more efficient than traditional casting processes, which is especially advantageous for complicated shapes,” says Masal. “With the development of innovative building materials and construction methods like 3D printing, the concrete industry is taking steps to mitigate carbon emissions.”
Dr. Masal believes that the combination of this new technology with further developments in design and performance, could pave the way for a more sustainable future in the construction industry. He said that he hopes the innovative 3D printing technique for producing strong, durable concrete with lower carbon emissions can help overcome some of the main hurdles in implementing additive manufacturing in the building industry.
“Further research will look at the performance of this approach with higher quantities of recycled aggregates,” he said. “By investigating the behavior of different types of aggregates, we can understand the complex relationship between materials and concrete, paving the way for further improvements and better sustainability.” The research, conducted in Arizona State University’s Construction Engineering and Management Laboratory, is another significant step toward the use of 3D-printed concrete in construction and towards reducing the environmental impact of concrete production and building practices.
