Construction 3D printing

Construction 3D Printing (c3Dp) or 3D construction Printing (3DCP) refers to various technologies that use 3D printing as a core method to fabricate buildings or construction components. Alternative terms for this process include "additive construction." "3D Concrete" refers to concrete extrusion technologies whereas Autonomous Robotic Construction System (ARCS), large-scale additive manufacturing (LSAM), and freeform construction (FC) refer to other sub-groups.

At construction scale, the main 3D-printing methods are extrusion (concrete/cement, wax, foam, polymers), powder bonding (polymer bond, reactive bond, sintering), and additive welding.

A number of different approaches have been demonstrated to date, which include on-site and off-site fabrication of buildings and construction components, using industrial robots, gantry systems, and tethered autonomous vehicles. Demonstrations of construction 3D printing technologies have included fabrication of housing, construction components (cladding and structural panels and columns), bridges and civil infrastructure, artificial reefs, follies, and sculptures.

3D concrete printing is an emerging technology with the potential to transform building and infrastructure construction by reducing time, material usage, labor requirements, and overall costs, while also enhancing sustainability and minimizing environmental impact. Despite its promise, the technology faces several challenges, including the development and optimization of material mixes, ensuring process consistency and quality control, maintaining structural integrity and durability, and addressing gaps in industry regulation and standardization.

In 1939 William Urschel created the world's first 3D concrete printed building in Valparaiso, Indiana. Urschel patented many of his construction inventions and even had 3D printing that utilized tongue and groove structural designs.

Robotic bricklaying was conceptualized at explored in the 1950s and related technology development around automated construction began in the 1960s, 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 1980s and 1990s. 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 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 cementitious 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.^{[citation needed]}