Naveen Verma (l) and Branko Glisic
Researchers from Princeton University are developing a high-tech type of polyimide sheeting embedded with sensors, batteries and integrated circuits that can be wrapped around buildings and bridges to detect their structural health.
The new product is the work of Professor Branko Glisic and Professor Naveen Verma who liken their new invention to the nervous system in the human body. It was highly commended in the CIOB International Innovation and Research Awards 2013.
The sensor system is formed of a very dense array of smart sensors which are interconnected and embedded into the sheeting. The layered integrated circuits collect and analyse the data and only alert the remote monitors if there is a problem.
“It’s like the human body, nerves don’t tell you you feel healthy all the time, but once you feel sick you’ll know it. And then you start investigating what the problem is,” said Prof Glisic.
Finally, flexible photovoltaics will be layered on top, to feed embedded batteries to provide power.
The sensor glued to concrete
“When we started developing the system we had bridges in mind, but we do see applications in buildings as well as aeroplanes and machines," added Glisic. “Building structures deteriorate over time. In Singapore buildings already have to be monitored with fibre optic strain sensors. But these can only be applied to certain parts of the structure.
“You wouldn’t cover a structure with our sheeting, but you would be able to cover larger areas prone to damage, to monitor more of it, more cheaply.” Glisic added: “The aim is to improve safety of structures, and therefore eliminate collapses of those that are only inspected periodically.
He said that commercialisation was still some time away, but he expected that a fully functioning prototype could be developed within two to three years.
The CIOB judges said: "The analogy of the human nervous system applied for the purposes of structural health monitoring is a brilliant idea. The sensing sheet technology has not only shown its originality in innovation, but has also shown its scope of application.”
… while lightweight concrete wins merit award
An engineer and inventor with a passion for concrete has developed a new lightweight version of the material which would help reduce the depth of foundations needed for tall structures like the Shard.
Philip Owens, who runs technical troubleshooting and research consultancy Nustone, received a merit award in the CIOB International Innovation & Research Awards for the new form of concrete.
"If you were to build structures using this lower weight of concrete they won’t need such deep foundations, which means they won’t interfere with tunnels and such like."
Philip Owens
While lightweight concrete is not new when formed as lightweight aerated blocks, Owens’ innovation is to mix a lightweight aggregate made from detritus clay, such as that produced from tunnelling, for example from Crossrail in London. He then mixes this with the normal concrete constituents of gravel, sand and cement.
Said Owens: “The weight of concrete made with normal aggregates is about 2.4 tonnes/cum. With our lower density material the weight can be designed to be between 1.5 tonnes and 2.4 tonnes/cum.
“If you were to build structures using this lower weight of concrete they won’t need such enormously deep foundations, which means they won’t interfere with tunnels and such like.”
Owens has yet to receive commercial interest in the product, which he said “wasn’t rocket science”.
“Cement manufacturers tend to be ingrained in ways of doing things, but I’m optimistic it will take off in the future in the same way using fly ash in concrete took a while to be accepted. But I probably won’t be around to see it,” added the 83-year-old.
