Australia Leading the Way in Construction and Building Materials

Source: Sally Wood

Australian researchers are at the forefront of materials science innovation.

Together, with their industry counterparts, scientists have been bringing research to life to transform Australia’s renewables and technology-first future. Two research projects, from Monash University and UNSW Sydney have been recently published. Together, these breakthroughs will improve a material’s damage tolerance by reducing the use of cement used in construction materials; and offer a design solution to moderate temperatures year-round

Researchers from Monash University recently discovered a design motif derived from the rigid external covering of invertebrates. This research may help to create more damage-tolerant materials for future building and construction projects. The cement industry is one of the largest producers of carbon dioxide. It creates up to 8% of worldwide humanmade emissions of this gas. But this research from Monash University will assist in reducing the use of cement by improving the material’s damage tolerance. Professor Wenhui Duan from the Department of Civil Engineering said the pattern can add a high strength motif to commonly used building materials like composites and cement, and may help in reducing carbon emissions. “We demonstrated the application of this design motif in producing a high strength, damage tolerant lightweight cement material,” he said. In addition, this design motif can also be applied to various materials like ceramic, glass, polymeric and metallic materials for advanced materials design, energy storage, conversion, and architectural structures. The research team replicated the design motif in cement material, which is one of the most consumed construction materials in the world. Together, they used a 3D printing technique combined with nanotechnology and artificial intelligence to fabricate a lightweight cement composite, which adopted a segmental design motif. This demonstrated a superior loadbearing capacity and a unique progressive failure pattern. Since the 1972 discovery of the helical structure—one of the most common structural patterns in biology—there has been a drive to extract design motifs from more than 7 million living species in the world. After 50 years of research undertaking, remarkable repetitions have been confirmed in most classes of species but only eight categories of design motifs have ever been extracted and adopted in materials design, until now. This design structure has been identified in various species such as the exoskeletons of arthropods, the legs of mammals, amphibians and reptiles. They are valuable sources of inspiration for modern materials design and aid the fabrication of structural material. “Compared to the current design motif, our segmental design motif dissipates the energy by segment rotation,” Professor Duan said. “The beauty of our discovered design motif is that the material can exhibit a unique periodic progressive failure behaviour.” “It means we can contain the damage within a particular region of material, while the rest of the structure can still maintain the integrity and most (around 80%) of load-bearing capacity,” he added. The research is widely available in Nature Communications, and forms part of the ARC Nanocomm Hub. This provides a centralised platform to transform the construction materials industry into an advanced manufacturing sector in sustainable and resilient infrastructure assets. Professor Wenhui Duan works at the interface of materials science and civil engineering. He is a Fellow of the Australian Academy of Technology and Engineering, and has been an early pioneer in the development of nanoscience and nanocomposites for civil engineering applications.

A team from UNSW Sydney has developed intelligent building materials that can help keep the temperature in check throughout the seasons. This innovative design solution adjusts the optical properties used in conventional heat mitigation materials to change the amount of heat they reflect and emit. The changes occur depending on the temperature in the air. The materials were designed by a team of researchers, who believe they can be used in buildings worldwide to better protect them from the elements. “This is a smart, intelligent building material that understands the urban temperature, and it is modulated according to the weather conditions. So it is ideal for cities that have issues with overheating in summer, but also have heating requirements during winter,” Professor Mat Santamouris said. Extreme urban heat is the most documented climate change phenomenon. It affects more than 450 cities worldwide. Higher urban temperatures significantly increase energy consumption needs and adverse impacts on health, including heatrelated morbidity and mortality. Professor Santamouris specialises in developing heat mitigation

The new materials used to coat buildings could help moderate temperatures in summer and winter. Photo: Shutterstock.

technologies and strategies that decrease urban temperatures. His team recently tested the new generation of materials in Kolkata, India. Many conventional cooling materials help mitigate urban overheating during warmer periods, but are not necessarily suitable for cities that have winter heating requirements. Because the materials reflect light, they can generate glare, and can only be used in specific locations. “Traditional supercool materials work by having very high reflectivity and emissivity, making them ideal for cities that only require heat mitigation.” “However, they can cause overcooling in cities that also need heating during cooler periods,” Professor Santamouris said. The research team worked with an international collaboration of colleagues from the University of Calcutta, India; Public University of Navarra, Spain; and the University of Tsukuba in Japan. The study is the latest in an ARC Discovery Project, which seeks to develop cooling technologies to mitigate urban overheating and reduce cooling energy demands in buildings. Researchers employed new layers to the conventional supercooling materials to help modify their solar reflectance and emissivity during colder periods without compromising the cooling efficiency. “They also can’t be used in low-level streets or vertical façades because of the glare, so they can only really be used on roofs of high-rise buildings— not in walls or pavements,” Professor Santamouris said. The first layer is composed of a ‘phase change’ material that uses transitional metal oxides to modulate the reflectivity and emissivity during the seasons. Then, a second fluorescent layer increases the cooling capacity of the material. “We have integrated a new layer into the materials which changes the reflectivity and emissivity as a function of the ambient temperature,” Professor Santamouris said. “We have also decreased the reflectivity of the materials to decrease glare by integrating [another] new layer that increases heat losses through fluorescence,” he added. Fluorescent materials absorb solar radiation but immediately re-emit it as a fluorescent emission at a lower wavelength. But this innovative solution compensates for the reflectivity loss and can be used without causing glare. This produces results that have a surface temperature below the ambient temperature during the summer months. As such, it provides cooling to the building, and then provides heating in winter. “It’s an intelligent material that is adaptable to any climate, can be used at a low level, and can be of any colour, and does not create any glare,” Professor Santamouris concluded.