Buildings and bridges could be turned into cheap batteries through new cement mixtures, according to researchers at Lancaster University, in the UK. The team has created a cement mixture which it claims can store electrical energy and monitor its own structural health.
The solution is made from flyash and chemical solutions and the novel potassium-geopolymetric (KGP) composites are reportedly cheaper than Ordinary Portland Cement. Researchers say they are easy to produce and do not need any complex or expensive additives.
Lancaster University’s news report, says “Alternative smart concretes rely on expensive additives such as graphene and carbon nano-tubes and, in addition to cost, these technologies do not scale up well preventing use in large structures.”
The KGP composites rely on the diffusion of potassium ions within the structure to store electrical energy and to sense mechanical stresses. The KGP mixtures could potentially store and discharge between 200 and 500 watts per square metre when fully optimised.
According to the report: “A house with exterior or partition walls built using KGP, when connected to a power source such as solar panels, would be able to store power during the day when empty and discharge it during the evening when the occupiers are home. Existing buildings could have KGP panels retro-fitted.”
Smart cement could also be used to take street lighting off-grid. A typical street lamp post uses 700 watts each night while a six-metre tall lamppost made using KGP could hold enough renewable energy to power itself throughout the evening. Additionally, KGP curb-stones have the potential to store enough energy to power smart street sensors monitoring traffic, drainage and pollution.
Large numbers of structure made with KGP could also store and release excess energy to help smooth demands on the grids, the report adds.
The researchers state the KGP mixtures are also self-sending. The changes in mechanical stress caused by cracks alter the mechanism of ion hopping through the structure and the material’s conductivity. These changes allow the structural health to be monitored automatically through measuring conductivity without needing more sensors.
Structures which include sections made from KGP at critical stress points may provide accurate alerts when cracking occurs.
Professor Mohamed Saafi from Lancaster University’s Engineering Department, and lead author of the study, says: “We have shown for the first time that KGP cement mixtures can be used to store and deliver electrical energy without the need for expensive or hazardous additives.
“These cost-effective mixtures could be used as integral parts of buildings and other infrastructure as a cheap way to store and deliver renewable energy, powering street lighting, traffic lights and electric vehicle charging points.
“In addition, the concrete’s smart properties makes it useful to be used as sensors to monitor the structural health of buildings, bridges and roads.”
The researchers are now carrying out studies to optimise the performance of KGP mixtures and they are also looking at 3D-printing as a way to use the cement to create different architectural shapes.
The research paper, entitled Inherently multifunctional geopolymetric cementitious composite as electrical energy storage and self-sensing structural material is set to be published in the journal ‘Composite Structures’ on 1 October.
