Page 4 - Open access sep 2020

TECHNICAL PAPER

CONCRETE

3D PRINTING –

PROGRESS WORLDWIDE

AND IN INDIA SHANTANU BHATTACHERJEE,

A. V. RAHUL, MANU SANTHANAM*

Abstract is cast or printed layer-by-layer through an automated process.
One of the major advantages of this printing technique can
This paper provides a review of the development of digital be attributed to less or no use of formwork. Binder jetting is
fabrication methods in the construction industry and academia, another technology used in 3D printing (Jakupovic, 2016). The
with a major emphasis on extrusion-based 3D printing. A construction is done by ejecting/spraying binders like droplets
detailed description of the work done by the research group in on the top of a build tray with a carrier material like sand or
IIT Madras in developing a Portland cement-based 3D printable cement, as shown in Figure 2.
formulation is discussed. Finally, the areas in digital fabrication
that require further research and attention are also highlighted ETH Zurich developed smart dynamic casting (SDC) (Lloret et
in this paper. al., 2017); this technique is similar to the slip-forming process
but done with a flexible formwork. It employs two different
Keywords: Digital fabrication, extrusion-based 3D printing, 3D shaping methods, the first at the exit point, to have minimum
printable concretes. deformation, and the other one globally, allowing variation
in cross-section. The continuous inline measurements and
1. INTRODUCTION automated feedback loops are used to control the loading on
the concrete already cast at the exit point of the formwork. SDC
Digital printing of concrete is based on the principle of 3D uses formwork pressure and friction measurements to define
printing technology or additive manufacturing. The prevalent upper and lower strength limits. The technology also allows the
processes of digital printing are extrusion-based printing, binder incorporation of reinforcement as the sliding formwork takes
jetting, mesh mould approach (cutting and welding), smart care of the pressure exerted outside, i.e. formwork pressure.
dynamic casting, etc. The additive process in construction with Using flexible formwork, the variable cross-sectional structures
automation is suggested by Pegna (1997) and further developed
by Khoshnevis (2004). can easily be constructed (Lloret et al., 2017). Mesh mould
approach for digital printing is developed considering the
Among all the processes, the most widely used method is the concept of ferrocement. The approach aims to fabricate the
extrusion-based printing (Figure 1). In this process, the concrete steel reinforcement digitally and to use it as a formwork. The

Figure 2: Binder Jetting using D Shape printer adapted from Jakupovic
Figure 1: Extrusion based printing (2016)

8 THE INDIAN CONCRETE JOURNAL | SEPTEMBER 2020
*Corresponding author : Manu Santhanam, Email : manusanthanam@gmail.com