An Australian inventor has won the silver prize of the Thomas Edison Award with a concrete-free footing system.
The award honours innovations and innovators, with Surefoot taking silver in the Energy and Sustainability – Commercial Construction category.
Neil Despotellis thought of the idea for Surefoot about seven or eight years ago when he was doing work on large cantaports about 6mx6m – the project required holes 2 m deep and 600 mm wide, requiring a lot of work to remove soil.
“I would spend probably two to three days on digging holes. That’s fine when you have machinery that can do the holes for you, but in a lot of cases they were in very tight places in backyards,” he said.
Not only did digging the holes take up a lot of time, but Despotellis said it also took up about 50 to 60 per cent of the cost of the project.
Despotellis started researching solutions that didn’t require concrete as a way of reducing cost and improving the speed of installation, such as using steel.
Product design
Surefoot is a patented steel footing system that has been developed to support a range of structures.
Despotellis initially designed the product as a flat plate. Collaborating with a certifying design engineer, he was able to improve the capability through a folded plate version, increasing model types, improving capacity and decreasing manufacturing costs.
The product is now based on a combination of shallow and deep foundation design principles, using the theory of bearing capacity of a shallow foundation, plus the skin friction and toe resistance of a deep foundation. It can be installed in any soil types.
Compared to traditional footing and piling systems, it only requires lightweight power tools to install and minimum site access.
The company says a cost saving of 50 per cent can be achieved when comparing the amount of steel versus concrete needed for uplift loads of around 5 tonnes.
As the product is a new way of doing things, with Despotellis calling it a “disruptive technology,” testing helped to overcome one of his biggest challenges – convincing engineers that Surefoot worked.
Along with his own tests, Melbourne University and Swinburne University have also tested the product to international standards, which Despotellis said made a difference in winning engineers over.
Tests included compression testing – placing a footing in the ground and putting up to a seven-tonne load on it and measuring the movement of the piles and Surefoot pile cap – as well as uplift testing to test the pull-out of the product in certain types of soil.
Unlike concrete piles, Surefoot does not require any digging or soil removal and can take just six minutes to put a footing in. This compares to concrete piles, which can take days once digging, soil removal and curing time are factored in.
Each system is designed for the conditions of a site, taking into account aspects such as the type of soil on-site, as this can influence the length of the piles and the plate size.
“Depending on the load going on it, for instance if we’re doing a standard house, we might only go down 1.2 m, but if we’re on a bad type of soil, we might go down 1.6 m. We can do nearly all types of soil,” Despotellis said.
Determining the soil type is a key part of installing the system, which is carried out by a geotechnical engineer, and can take as little as five minutes to get a result.
One of the first major projects to use the product was in around 2010 or 2011 in a project in Western Australia to support miners’ accommodation that was up to two-storeys high.
Since then, Despotellis said the product has been through only minor changes, and has even been used in the renovation of a yacht club in Melbourne that involved submerged piling.
In order to deal with the pilings being underwater, Surefoot used stainless steel, with footings bearing loads of up to 30 tonnes each. Despotellis this would have been almost impossible to achieve with concrete, due to the water making it difficult to dig holes.
“The hole got bigger and bigger as you started digging them. As it was partly underwater, we actually installed our footings in the water as well,” Despotellis said.
Surefoot can also be used in other projects where using concrete would be difficult, such as on projects with steep terrains.
On one such project, Surefoot was installed on a sloping plot of land where using machinery was impossible. Digging a hole and pouring in concrete was also not an option.
But Despotellis said as Surefoot has a minimal disturbance on the land and soil, it overcomes the problem on these types of projects, where water drainage can easily divert straight into a newly dug hole.
Surefoot has now been specified in a range of projects around the world, with the product licenced in Europe, Africa, China and New Zealand. But Despotellis said he is continuing with testing to keep refining the product and improve its cost effectiveness.
“My whole idea with Surefoot is the testing is not going to stop,” he said.
“There is so much variance in soil, that I believe testing has to continue all the time to keep improving it.”