Insight #2: Resource Efficiency
The concrete industry is a net consumer of waste
THAN IT SENT TO
Doing more with less’ is a useful summary for resource efficiency and one frequently used in the context of structural design solutions. But just as embodied CO2 does not represent a true carbon footprint, resource or material efficiency should not be considered at just a single lifecycle stage. As with so many aspects of sustainable construction, the most effective solutions require a holistic, whole-life approach.
Concrete and masonry can offer material efficiency at each stage of development, providing varied opportunities to do more with less. This is in part demonstrated by the industry project with WRAP and stakeholders that delivered Resource Efficiency Action Plans for ready-mixed concrete, precast concrete and blocks (see overleaf ), outlining opportunities from factory gate to end of life.
The ability of concrete producers to use waste and by-products from other industries has enabled the industry to become an overall net consumer of waste. During the production process for cement, the sector can safely burn a wide range of materials as alternative fuels such as solvents, tyres, meat and bone meal, sewage sludge, unrecyclable paper and plastic.
The raw virgin materials in concrete can also be replaced with recycled materials and byproducts from other industries. Ground granulated blast-furnace slag (GGBS) is a by product of iron production and fly ash is from electricity generation.
Both are used, in combination with Portland cement, as the cementitious material in concrete and make a valuable contribution towards the durability of concrete and the lowering of its carbon footprint. Recycled and secondary aggregates can be used in concrete (at levels permitted by British Standards) – and the concrete industry’s sustainability strategy introduced a performance indicator to chart this (see page 28).
However, due to the logistics of retrieving suitable segregated concrete and aggregates from construction sites and returning them to separate concrete production plants, the CO2 associated with transport alone can outweigh environmental benefits. The most efficient investment of resources is in a structure that is designed for longevity, and concrete and masonry have the durability and robustness to achieve this.
Infrastructure projects often have a design life of over 120 years; our housing stock needs to be robust to the impacts of climate change; and our commercial buildings need to be designed to be adaptable to future requirements.
This can all be achieved with concrete. And when refurbishment is no longer an option, concrete can be recycled. Concrete is often seen as ubiquitous and low cost and so its use may not be considered as carefully as materials that are scarce or expensive. However, its inherent properties and performance make it an asset to any material-efficient design strategy.
The concrete industry, via The Concrete Centre, provides designers with detailed information on how material use in buildings can be reduced using concrete, including guidance on materialefficient solutions such as posttensioned concrete.