According to reports by Mordor Intelligence, the UAE construction market is expected to register a CAGR of 5.5% between 2019 and 2024. Some factors for growth are construction linked to the upcoming Expo 2020, government drive to boost tourism, focus on Smart Cities and foreign investors propelling the construction market in UAE.
This industry relies heavily on the use of concrete. As a building material, it is easily fabricated, and its great simplicity lies in the fact that its constituents are readily available almost anywhere in the world. The functionality and flexibility of concrete has resulted in it becoming the most popular and widely used construction material in the world.
At the same time, the production of concrete has a huge impact on the environment in several ways as follows: energy use is high, machinery is heavily dependent on fossil fuels, the fabrication and shipping of materials can have a great impact on carbon emissions and the mining for raw materials can result in pollution of local water tables. In fact, according to studies by the International Energy Agency, the construction industry accounts for an incredible 36% of worldwide energy usage, and 40% of CO2 emissions. The IEA further estimates that for every kilogram of cement produced, around the same amount of CO2 is released into the atmosphere.
This has resulted in a quest for sustainable construction using materials that are more environmentally friendly than concrete. When sustainable building materials are used, they reduce the impact on the environment, can bring about reduced operating costs and can boost a brand’s reputation by demonstrating its sense of corporate social responsibility.
Matt Smith, associate head of the School of Energy, Geoscience, Infrastructure and Society (EGIS) at the Heriot-Watt University Dubai campus, provides an overview of some of the ways by which concrete, and its use can be made more sustainable.
Innovative architecture and structural design
Using less cement is the most effective way to reduce the carbon footprint of concrete and this can be achieved through efficient and innovative design. There are several ways to optimize material efficiency to reduce concrete use. For example, using shorter bay sizes can allow for thinner slabs. Another is replacing conventional concrete with another kind known as geopolymer concrete made by reacting aluminate and silicate bearing materials with a caustic activator. Reports state that up to 50% of the conventional concrete used in construction can be replaced with geopolymer concrete. And finally, different construction techniques can also bring down the usage of concrete. An example is grasscrete, which is a method of laying concrete flooring, walkways, sidewalks, and driveways in an open pattern allowing grass or other flora to grow. Such a design reduces concrete usage overall while improving stormwater absorption and drainage.
Use of environmentally friendly materials where possible
The drive for sustainable construction materials has resulted in many substitutes for concrete. Straw bales can be used to create a home’s walls inside of a frame, taking the place of concrete. Apart from being affordable, straw bales naturally provide very high levels of insulation for a hot or cold climate. Another example is the well-known wood. Wood offers many advantages that concrete does not. Trees absorb CO2 as they grow, can be processed into construction products with less energy and forests are renewable. Yet another is ferrock – a new material being that uses recycled materials including steel dust to create a concrete-like building material stronger than even concrete. Additionally, ferrock actually absorbs and traps carbon dioxide, making it a carbon neutral material.
Use of admixtures
Sustainable alternatives are only part of the solution. The other part lies in finding ways to increase the lifespan of existing concrete structures, so there is no need to rebuild them. This is most commonly done through the use of admixtures – chemicals which are added to the concrete before or during the mixing stage. Admixtures are normally air-entraining agents, water reducers, water-reducing retarders and accelerators. Concrete admixtures can improve concrete quality, manageability, acceleration, or retardation of setting time and more, depending on desired results. One area of application is in extending the lifespan of concrete. Premature deterioration of concrete infrastructure is an economic cost as well as an environmental impact. Admixtures such as flyash, silica fume, and other pozzolans as well as chemical admixtures can improve the microstructure of concrete and increase life span by more than 100 years.
Asphalt vs concrete roads
Asphalt and concrete are two materials used to pave a road and the while asphalt costs less initially, concrete lasts longer. Roads are a significant part of the construction pie; therefore, it is worth investigating which material – asphalt or concrete – is the better choice. Roads experiencing heavy traffic, especially trucks could possibly be better off constructed from concrete, as it holds up better under heavy loads. On the other hand, asphalt provides a smoother ride, is ready to drive on as soon as it is compacted by a roller and can be repaired just with the use of relatively simple equipment. In the Middle East, the Ministry of Infrastructure Development (MoID) is actively working towards achieving sustainability, encouraging recycling and creating a national green road network. Initiatives include construction of sustainable roads through the use of recycled rubber asphalt.
Recycling of concrete
Concrete can be 100% recycled. Not only that, recycling keeps it out of landfills. As part of the recycling process, concrete is normally crushed and used as secondary product for applications such as gravel, paving materials, and aggregate or even as fill material. Concrete has the natural ability to absorb some amount of CO2. The grinding, crushing and spreading concrete to maximize its surface area at its end of life results in this absorption, is yet another step towards sustainable construction and preferable to manufacturing and usage of fresh concrete.