From bricks made of mushrooms to energy-generating paint, Construction News takes a look at some of the innovative building materials and products set to transform the industry
Bio-concrete
The Global Concrete and Cement Association says that concrete can self-heal to a degree. But one way to increase concrete’s self-healing ability is the inclusion into the concrete mix of micro-organisms that produce calcium carbonate (limestone). When this bio-concrete is damaged and the bacteria is exposed to water, it produces limestone which fills the cracks. Loren Burnett, chief executive and co-founder of Prometheus Materials, which produces a bio-cement, says the company’s bio-cement process harnesses the abilities of naturally occurring microalgae. However, a 2022 study found that high pH levels and mechanical stress in the first few days of placement could kill the bacteria and severely reduce the ability of bio-concrete to self-repair.
Graphene-enhanced concrete
Replacing some of the cement content in concrete can cut embodied carbon while also improving performance. A January 2022 peer-reviewed study by the University of Wollongong found that using graphene-enhanced concrete could enhance the durability of concrete and mortar exposed to corrosive water environments. Tests indicated that, based on the mix formulation for wastewater infrastructure, First Graphene’s PureGRAPH 50 product delivers a 10-20 per cent improvement in 28-day compressive strength. However, a December 2023 case study from the University of Hafr Al Batin in Saudi Arabia described “inherent environmental risks” from graphene-enhanced concrete. For instance, graphene concrete is classified as hazardous waste and “requires stringent management practices during its disposal”, the Saudi study said.
Hempcrete
According to the Alliance for Sustainable Building Products, HCB Hempcrete Blocks are made by combining the woody stem of the industrial hemp plant with a lime binder. The blocks, supplied by UK Hempcrete and manufactured by Equilibrium in Italy, are a low-embodied-carbon alternative to conventional insulated walling systems. The combination of hemp and lime is naturally resistant to fire, pests and rot. This means that no additional chemical treatment is needed, so there are no harmful chemicals in the final product. HCB blocks are hygroscopic, so they passively regulate internal humidity to avoid condensation and damp. However, UK Hempcrete has noted: “Examples can be found where a lack of understanding of the material and proper construction techniques has resulted in problems” at the construction stage.
Photovoltaic glass
Photovoltaic glass can be used as a material for building purposes as well as generating electricity from sunlight. The panes are made of layers of heat-treated safety glass that can provide the same thermal and sound insulation as conventional architectural glass. At the same time, it lets natural light into a building in the same way as conventional glass. Photovoltaic glass has a higher upfront cost than the conventional product. But by providing the same thermal insulation as conventional glass while generating free clean electricity from the sun, the product enables improved energy efficiency, decreased operation and maintenance costs, and a lower carbon footprint.
Solar paint
While not yet on the market, multiple companies and research institutions are developing different types of solar paint that can generate clean electricity and be used alongside photovoltaic cells or as a standalone application. Researchers believe that solar paints could be used in multiple ways, including on buildings and homes that are not suitable for the installation of cells. Alternatively, they could be applied to existing clean energy infrastructure, such as wind turbines, to provide a more consistent flow of energy. But according to industry body Solar Action Alliance, the efficiency of solar paint ranges between 3 and 8 per cent. In comparison, traditional solar panels are 20 per cent efficient, with experts saying that solar paint will have to be 10 per cent efficient for it to be commercially viable.
Better bricks – from recycled aggregate to fungus
Recycled material bricks
Bricks made from recycled materials are sometimes given the misnomer of ‘recycled bricks’, which could leave the impression that they are salvaged from demolition sites. Those are actually called ‘reclaimed’ bricks, while recycled material bricks are completely new products, and are sometimes called ‘waste’ bricks. Waste bricks are produced from waste clays and chalks. One example of this is the K-BRIQ, which is made from over 90 per cent aggregates from construction and demolition waste, including old bricks, rubble and mortars. Manufacturer Kenoteq says that producing the K-BRIQ consumes less than 10 per cent of the energy used in traditional clay brick production. In addition, manufacture and cure takes less than 24 hours. A study in the International Journal of Engineering and Technology found that bricks made from ordinary Portland cement and fly ash – mixed with construction and demolition waste as coarse and fine aggregate – were stronger and less water absorbent than conventional burnt clay bricks.
Plastic bricks
Manufacturers of plastic bricks have proliferated across the world. Charity Recycle Rebuild has worked with Netherlands-based Precious Plastic to develop a brick made from 100 per cent recycled plastic, while Kenyan social enterprise Gjenge produces paving blocks from plastic waste. A study by researchers in South Africa found that masonry bricks made from scrap plastic waste and foundry sand had a compressive strength that was 2.5 times higher than clay fired bricks. However, a 2019 study in the International Research Journal of Engineering and Technology said that plastic bricks are “useful for the construction industry” but there are potential drawbacks, including that it can be difficult to bond plastic with conventional mortar. Another downside of plastic bricks is that they can be difficult to keep clean because of their porosity, so they are not suitable for rooms like bathrooms. In addition, plastic can deform when exposed to strong sunlight or extreme cold.
Pollution-absorbing bricks
Conceptualised as building materials that can filter harmful particulates from the air, pollution-absorbing or air-purifying bricks are being put forward as a solution to poor indoor air quality. One such product is the Breathe Brick, developed by professors and staff at California Polytechnic State University. The university says: “As part of a two-wall system, the brick forms the exterior structural wall separated from a typical insulated partition by a ventilation gap.” But according to architecture forum Rethinking the Future, the exterior wall takes up to double the original space, which leads to contraction of the interior space.
Mycelium bricks
Mycelium is the root system of fungal organisms. When hardened, it turns into a tough water and fire resistant material and is already used for packaging. When it comes to building materials, researchers believe it has a lot of potential, although its application to date has been limited to temporary structures such as art installations. While stronger than traditional products relative to their weight, mycelium bricks are less reliable as a weight-bearing material and are prone to break down in poor conditions. Nevertheless, interest in mycelium bricks is growing, not least because they are potentially 100 per cent biodegradable and made from renewable material.
Read our feature on Material Changes
