Researchers at Lancaster University have developed a cement mixture, consisting of the waste material flyash and an alkaline solution, which is capable of conducting electricity.
Unlike existing smart concretes, which are typically based on graphene and carbon nanotubes, the new mixture does not contain any expensive materials, and is even cheaper to produce than conventional Portland cement.
In the mixture, known as a potassium-geopolymeric (KGP) composite, electricity is conducted via potassium ions that hop through the crystalline structure, according to project leader Professor Mohamed Saafi, from Lancaster University’s Engineering Department.
“To make cement you have to mix the flyash with an alkaline solution, in this case we use potassium hydroxide and potassium silicate,” he said. “When you mix them together they form a cement material, containing potassium ions that act as the electrolyte.”
The mixture could ultimately store and discharge between 200 to 500W/m2.
A house constructed with exterior or partition walls made with KGP, for example, could store electricity from solar panels during the day, and discharge it at night. Panels built from KGP could also be retrofitted onto homes and other buildings.
A six-metre tall lamppost built from KGP would be capable of storing enough renewable energy to power itself through the evening – typically around 700W.
Meanwhile curb stones could provide power to sensors capable of monitoring traffic, drainage and pollution levels.
Large numbers of KGP-built structures could also be used to balance the grid, storing excess renewable energy and releasing it when demand is high.
“We’re trying to turn buildings and bridges into batteries to reduce the cost of energy,” said Saafi. “At the moment we have a lot of renewable energy sources, but we don’t have a large-scale storage system for all that energy.”
The smart cement mixture can also be used to sense mechanical stress on the structures. Changes in stress, cause by cracks, for example, alter the way potassium ions move through the structure, and therefore the material’s conductivity.
By measuring the material’s conductivity, changes in the structural health of the building could be detected automatically and instantaneously, without the need to install additional sensors.
The researchers are now carrying out further work to optimise the performance of the KGP mixtures, and investigating the use of 3D printing techniques to create different shapes from the smart cement.
The research, which will be published in the journal Composite Structures in October, has been funded by the European Commission’s Horizon 2020 programme, as part of the SAFERUP (Sustainable, Accessible, Safe, Resilient and Smart Urban Pavements) project, led by the University of Bologna.