Construction 3D Printing Explained : Pre-History
Seeding technologies 1950 - 1995
Robotic bricklaying was conceptualized and explored in the 1950's and related technology development around automated construction began in the 1960's, with pumped concrete and isocyanate foams. Development of automated fabrication of entire buildings using slip forming techniques and robotic assembly of components, akin to 3D printing, were pioneered in Japan to address the dangers of building high rise buildings by Shimizu and Hitachi in the 1980's and 1990's. Many of these early approaches to on-site automation foundered because of the construction 'bubble', their inability to respond to novel architectures and the problems of feeding and preparing materials to the site in built up areas.
Early developments 1995 - 2000
Early construction 3D printing development and research have been under way since 1995. Two methods were invented, one by Joseph Pegna  which was focused on a sand/cement forming technique which utilized steam to selectively bond the material in layers or solid parts, though this technique was never demonstrated.
The second technique, "Contour Crafting" by Behrohk Khoshnevis, initially began as a novel ceramic extrusion and shaping method, as an alternative to the emerging polymer and metal 3D printing techniques, and was patented in 1995. Khoshnevis realized that this technique could exceed these techniques where "current methods are limited to fabrication of part dimensions that are generally less than one meter in each dimension". Around 2000, Khoshnevis's team at USC Vertibi began to focus on construction scale 3D printing of contentious and ceramic pastes, encompassing and exploring automated integration of modular reinforcement, built-in plumbing and electrical services, within one continuous build process. This technology has only been tested at lab scale to date and controversially and allegedly formed the basis for recent efforts in China.
First generation 2000 - 2010
In 2003, Rupert Soar secured funding and formed the free-form construction group at Loughborough University, UK, to explore the potential for up-scaling existing 3D printing techniques for construction applications. Early work identified the challenge of reaching any realistic break-even for the technology at the scale of construction and highlighted that there could be ways into the application by massively increasing the value proposition of integrated design (many functions, one component). In 2005, the group secured funding to build a large-scale construction 3D printing machine using 'off the shelf' components (concrete pumping, spray concrete, gantry system) to explore how complex such components could be and realistically meet the demands for construction.
In 2005 Enrico Dini, Italy, patented the D-Shape technology, employing a massively scaled powder jetting/bonding technique over an area approximately 6m x 6m x 3m. This technique although originally developed with epoxy resin bonding system was later adapted to use inorganic bonding agents. This technology has been used commercially for a range of projects in construction and other sectors including for [artificial reefs].
One of the most recent developments has been the printing of a bridge, the first of this kind in the world, in collaboration with IaaC and Acciona.
In 2008 3D Concrete Printing began at Loughborough University, UK, headed by Richard Buswell and colleagues to extend the groups prior research and look to commercial applications moving from a gantry based technology  to an industrial robot, which they succeeded in licensing the technology to Skanska in 2014.
^ Patent by Dini et. al, "Method and Device for Building Automatically Conglomerate Structures. Patent number US20080148683 A1" web cited 2016-07-18