According to a report from Inhabitat, there’s no need for any adhesive or binding agent at all with the tunnels built by Lock-Block‘s new custom Zipper truck. The video below shows the truck in place where the new tunnel will stand as the large concrete blocks are put into place around a tapered trailer covered in rollers behind the truck. The blocks have interlocking pegs so that they connect and compress together as the truck moves forward, much like how an actual zipper works.
The process means you can build a quarter-mile archway in less than a day, and there’s no need to wait the normal 28 days for curing. To demonstrate the tunnel’s strength, the video shows an excavator drive on top with no problem at all. And these blocks can even be taken down and reused whenever needed.