The building industry is one of the largest contributors to greenhouse gas emissions. To address this, many new construction materials are incorporating eco-friendly elements that reduce embodied carbon.
One example is cross-laminated timber, which uses wood that has been shaped and glued under tremendous pressure. Other innovative materials include memory steel, which could be a gamechanger for infrastructure.
Cross-laminated timber
With construction being responsible for a significant portion of global carbon emissions, designers and builders have been scrambling to find materials that reduce the environmental harm caused by building structures. A recent breakthrough is cross-laminated timber, which consists of several layers of structural grade wood that are stacked and glued together to create solid, energy-efficient buildings.
CLT has been used in Europe for a few decades, but it’s now starting to gain traction in the US, where construction firms are using it to build homes and other buildings that are lighter, stronger, and more energy-efficient than those built with traditional concrete and steel. CLT is made by stacking and gluing kiln-dried lumber boards in perpendicular layers. These boards are then fabricated into panels that can be custom-manufactured to meet the specifications of a project, and they’re typically crane-guided onto a building site.
The biggest reason why CLT is a sustainable building material is that it’s made from wood, which comes from a renewable resource (especially when gathered from sustainably managed forests) and doesn’t require fossil fuels during production. Furthermore, the wood in CLT has captured some of the atmospheric carbon dioxide during photosynthesis, so it can continue to sequester carbon as long as the building stands.
In addition to its green attributes, CLT is easy to work with and can be recycled at the end of its life cycle. Additionally, CLT is naturally insulated and requires less energy to heat and cool, which can further reduce a building’s carbon footprint.
Memory steel
Architects and builders have long relied on concrete and steel to build buildings, but these three materials are among the most energy-intensive and emit the most greenhouse gases. Fortunately, there are several new green building materials that can reduce emissions and create more environmentally friendly buildings.
One such material is memory steel. Memory steel is a shape-memory alloy that contracts when heated and can be used to reinforce concrete structures. Its use could help to reduce the amount of water and electricity needed in a building, which would cut down on emissions and save money.
Another promising green construction material is cross-laminated timber. This is made from small pieces of softwood glued together and pressed under tremendous pressure in opposing directions to give it superhuman strength. It also allows for wood that has been affected by drought or insects to be included in the structure without compromising structural integrity.
As a result, it’s a sustainable, affordable and durable alternative to traditional steel. However, one of the barriers to its adoption is that individual developers do not routinely count the embodied carbon in their construction projects. To address this issue, contractors can form buyer’s clubs to aggregate purchase commitments and seek out offtake agreements with near-zero emissions mills. They can also use environmental product declarations and life cycle assessments to support their quantification of embodied carbon.
Volcanic rock
Volcanic rock is a material that is readily available, as it comes from volcanic eruptions and fissures in the Earth’s crust. It is also aesthetically appealing, as some minerals in the rocks can reach sizes that make them useful for decorative purposes, such as the polished banded rhyolites and basalts used to create artisanal pottery (Figure 74.3).
A volcanic rock’s textural characteristics depend on how quickly it cools: If lava cools slowly, it forms a coarse-grained rock called an intrusive igneous rock. If it cools almost instantly, the magma becomes an extrusive igneous rock that is fine-grained and glassy, like obsidian.
The same volcanic rock can be pulverized into a fine powder and mixed into concrete, which requires less energy to produce than traditional cement. According to a recent study by engineers at MIT, replacing up to 50 percent of the traditional cement with volcanic ash can reduce a structure’s embodied energy by 16 percent.
In addition to the embodied energy savings, volcanic ash also has other sustainable advantages: it is readily available worldwide; it contains abundant silica and aluminum, which give concrete its strength; it can bind with water to form a paste that makes it stronger than pure limestone; and it is rich in magnesium, which enhances concrete’s durability. A concrete mix containing volcanic ash can also be shaped to mimic the appearance of traditional bricks.
Martian concrete
As humans prepare to move beyond our planet’s atmosphere, researchers are working hard to turn the red dust of Mars into a durable building material. A team of scientists led by Lin Wan from Northwestern University has formulated a construction material that uses Martian soil mixed with molten sulphur to create an amazingly strong concrete-like material that can be printed with 3-D printers.
Known as StarCrete, the new material is far more sustainable than traditional concrete. Currently, 5 to 8 percent of all greenhouse gas emissions come from cement and concrete production. This is because it requires huge amounts of energy, which usually comes from fossil fuels. Using the new material, however, could cut this figure dramatically.
The key advantage of StarCrete over regular concrete is that it doesn’t require water to form. This is vital on Mars, where water in the form of ice is a scarce commodity and the vast majority of the planet’s surface is a hostile desert.
Using the new material will also make it easier to build on the surface of Mars, where a lot of work is still needed to find ways to protect people from cosmic radiation and extreme temperatures. It’s hoped that the material will be particularly suitable for modular underground living, which would also help to expose underground ice and permafrost for in situ resource utilization (ISRU). In addition, the new material could even be used to print structures with complex shapes, such as domes and curved walls, that cannot easily be made from conventional concrete.