Another team of students build a conrete printer that looks like better quality than the last one. But no details on it. Its based off of a rep-rap and looks like it uses alot of PVC and wood. The quality is pretty impressive, so I wonder what they did for an extruder and concrete mixture.
http://3dprintingindustry.com/2015/07/30/texas-student-builds-backyard-concrete-3d-printer-everyone/