The Current Condition Of 3D Concrete Technology

Background of 3D printing

3D printing, also known as additive manufacturing (AM). It is a group of emerging techniques for create 3D structure directly from a digital model, in different layers. Which helps to decrease the amount of waste material.

Current technology for concrete printing

In the last few year, for concrete concrete construction the various 3DCP technologies have been developed to adopt AM. These technologies are mainly based on two technologies

Extrusion based technique

This technology is mainly made by analogous to the fussed deposition modelling (FDM) method, which extrudes cementitious material from a nozzle mounted on a gantry, crane or 6 axes robotic arm to print a structure layer by layer. This method is mainly used for the large scale buildings with the complex geometries and it is aimed at the on-site construction

a) Con print 3D: Concrete on site 3D printing. It is developed at TU Dresden, Germany. In which bring 3DCP directly in to the building sites

b) Large scale 3D: CP using ultra high performance concrete. This is the new technology has been introduced by the research team in France for the large scale 3DCP using UHPC. Here, it is an extrusion based technique• In which deposit the UHPC layer by layer through an extrusion print head mounted on 6 axes robotic arm.

Powder based technique

The powder based technique it is an another typical AM process. Here, which can construct accurate structure with complex geometries. Here, the main functions is depositing binder liquid in to powder bed to bind powder. Then it impacts the bed. It is an offsite process. Then it can be used for the precast components

a) Powder based 3DCP using geo-polym. Recently, the research team was develop an innovative technology to adopt geo-polymer based material.

b) This is for the requirement and demand of commercially available powder based 3D printers

c) It is the best alternative to OPC

d) It is formed due to the alkaline activation of flyash, industrial by products of coal power station & iron manufacture

e) Geo-polymers has superior mechanical, chemical & thermal properties.

Compressive strength of the structures

To prepare geo-polymer powder, anhydrous sodium. Meta silicate beads dry milled in planetary ball mill for 5minutes with ceramic balls. Then in hobart mixture dry mixed the materials like slag, anhydrous sodium meta silicate & fine sand. Then we get a homogeneous material. Here use the cube with 20x20x20mm size & 56x35x25mm complex geometrical structure. Before and after the post curing compressive strength of the printed cubic structure was measured in both X orientation & Z orientation. In saturated anhydrous sodium meta silicate solution in which the cubic structure is immersed for 1day & 7 days at 60 degree Celcious.