Bringing 3-D printing to concrete
For the last two years, Skanska UK has been part of a research consortium studying the possibilities of using 3-D printing to create complex concrete shapes. In prototypes, an advanced six-axis robot produces specialized facade panels and other pieces by extruding a bead of concrete about 10 mm in diameter, making passes back and forth in rapid succession. The concrete has fine aggregates, and it is reinforced both through fibers contained in the mix and by printing the pieces with voids to enable post-tensioning.
“Imagine a building for which every cladding panel is different – suited to the angle of the sun or acoustic requirements – and there is no additional cost to making it completely custom,” says Sam Stacey, Skanska UK head of innovation. “That flexible customization is what 3-D printing offers construction.”
Taking robots to new heights
So many connections for utilities and ceilings must be made to the underside of floor slabs in buildings. Traditionally, this involves much drilling done by workers raised on work platforms, which introduces safety risks and presents other challenges. For a better approach, Skanska Norway – together with an innovative robotics company – is exploring using robots for this work.
“On a recent test during construction of Skanska Norway’s new head office, a drilling robot mounted on a mobile elevated work platform performed two-and-a-half times faster than a comparable two-person crew doing the same work via traditional means,” says Rupert Hanna, global Building Information Modeling (BIM) knowledge manager.
Enabling the robot’s work was the precise drilling pattern it was fed from a 3-D digital model. Skanska Norway hopes to begin using this approach commercially later this year.
Better solutions for handling concrete reinforcing
Installing concrete reinforcing bars is heavy and time-consuming work, and an enormous amount of these rebars are installed every year. We see robots as a better way of doing much of this activity. Near Gothenburg, Skanska Sweden uses robots to bend and weld rebars to use in manufacturing concrete foundation piles. These rebar-welding robots are part of a highly automated system for pile fabrication.
“We purchased our first robot for this application in the 1990s, and this year the robots will enable this facility to produce 175,000 meters of concrete piles,” says Fredrik Andersson, district manager of Skanska Sweden’s foundation unit.
Automating building module assembly
Another far-reaching robot application we see is with building pod assembly. In this research, funded in part from Innovate UK, Skanska UK is exploring how robots can be used for mechanical, electrical, plumbing and carpentry tasks to produce building components. This work would be done in mobile “flying” factories that allow near-site manufacturing in controlled conditions.
“In construction, implementing new techniques tends to be a slow process,” says Stacey. “But Skanska sees it as fairly inevitable that we will be doing more construction off site, and in doing that work we will be using an increasing amount of robotics.”
He adds: “This is absolutely the direction that construction is heading.”