Insight #4: Water
The concrete industry has cut mains water consumption by almost 10%
PUBLISHED IN 2017
Climate change and population growth are adding to the complexity of water resource management, increasing the incidence of summer drought and large-scale flooding at any time of year. Water is important at many stages of concrete production.
It is essential to the hydration of cement, which enables it to act as the main binder for concrete, and is also used for washing during the extraction of aggregates, as quenching for GGBS, during the mixing and placing of concrete, for cleaning plant and in dust suppression measures. In some parts of the concrete supply chain water use can be reasonably clearly defined.
In others, such as the extraction of aggregates, there is often large-scale water movement – for example, for washing – that does not involve “consumption” as such. The Concrete Industry Sustainable Construction Strategy included a commitment to develop a water strategy and targets for the reduction of water consumption.
Recognising that the public mains supply is the least sustainable source of water for concrete production, the industry has been measuring mains water usage and reporting annually on efforts to reduce mains water consumption. In the base year 2008, the value was approximately 86 litres/tonne and in 2016 approximately 78 litres/tonne, a 9.3% reduction.
This has been achieved by using alternative sources such as licensed water abstraction, recycled production water and harvested rainwater. Waterreducing admixtures are now used in most types of concrete. Recent developments in highperformance water reducers and such innovations as “wash-water admixtures”, which allow residues in mixer trucks to be treated and reused, have also contributed.
The MPA Water Strategy was published in 2017 following review of the processes used in the concrete supply chain. This is based on three main principles: 1. Minimising water consumption 2. Prioritising use of the most sustainable water sources available 3. Protecting the environment through good water stewardship The concrete production sectors are now working to produce more detailed action plans, which are also part of the industry Resource Efficiency Action Plans.