Concrete plays a key role in water supply infrastructure, since it provides an easily-realised means of holding and transporting water.
Concrete production is currently a major contributor to anthropogenic carbon emissions. Much research has rightly focused on reducing the embodied carbon of concrete through the use of alternative materials and manufacturing techniques. However, it is unlikely that net-zero can be achieved purely by this route without offsetting. Therefore, to address this, the best complementary strategy is to move towards the design of infrastructure whose intended service lives are considerably greater than current practice – ‘diluting’ embodied carbon through longevity. Longevity is achieved through ensuring that concrete is durable.
One of the key threats to the durability of concrete used for such purposes is ‘soft water leaching’. This occurs when water with a low concentration of dissolved salts comes into contact with concrete, particularly under fast rates of flow. Soft water leaching is of particular concern in Scotland, where high purity and predominantly igneous geology makes the majority of water soft.
The vulnerability of concrete to soft water leaching is very dependent on the chemical composition of the cement used. The number of cement components available is now relatively wide and includes a number of industrial by-products whose use allows the embodied carbon of concrete to be significantly reduced. However, porosity is also important, and this is strongly influenced by the extent to which the particles that make up concrete pack together efficiently. The aim of this project is simultaneously use both these approaches to develop a method for designing concrete which maximises the resistance of concrete to soft water leaching, whilst maintaining low embodied carbon.
The approach that will be taken will combine computer modelling (using a technique known as geochemical modelling, plus established particle packing models) with laboratory experiments. This approach is useful, since it allows the process of identifying cement formulations which should perform optimally against soft water leaching to be identified rapidly by investigation in theoretical terms, followed by experimental verification and refinement. The initial modelling approach may also turn out to be useful in that this approach may be incorporated into the design process.