TRANSITION FROM TRADITIONAL COB CONSTRUCTION TO 3D PRINTING OF CLAY HOMES

3D printing of cementitious material can provide an affordable, sustainable, and optimized approach for the construction of homes, without compromising quality or craftsmanship. While most of the current research and development efforts in this field are focused on cement-based concrete printing, this paper focuses on the current state-of-the-art literature review of designing and developing a sustainable clay-based mixture design that mainly includes clay, sand, straw, lime, and water. The goal of this paper is to bridge the gap between typical traditional earth construction, specifically cob construction, and emerging 3D printing of cementitious materials. The specific objective of this paper is to offer some possible changes in the typical cob mixture so that it can be used for 3D printing of clay-based mixtures with sufficient flowability, buildability, strength, and open time (i.e., the time period between printing of one layer and printing of another layer deposited on a layer below). The paper describes typical clay-based mixtures and their traditional process and then specifies the challenges in going from traditional cob construction to advanced computer-controlled robotic 3D printing.