3D printing of geopolymer mortar: Overview of the effect of mix design and printing parameters on the strength

Abstract

In the last centuries when the Additive Manufacturing (AM) started, the major focus was on mostly plastic and metal printing process. Using AM, the production of goods made of plastic and metal increased a lot. Nowadays concrete is also produced by printing commonly known as Three Dimensional Concrete Printing (3DCP). 3DCP is a process where a concrete like materials are extruded through a designated size and shape of the nozzle. The nozzle can be placed on a gantry or just connecting with a robotic arm and extruded any designated shape according to their digital design input. The aim of this paper is at summarizing the effect of mix design and printing parameters on the compressive and flexural strength of 3D printable geopolymer concrete. The results are collected from the published literatures from different parts of the world specifically on 3D printable geopolymer mortars. Various relationships are developed for mixing parameters such as activator to binder ratio, mix density, viscosity and compared with their corresponding compressive and flexural strengths at 7 and 28 days. Similarly, strengths for printing parameters such as nozzle types, position of nozzle and loading direction are also investigated. A statistical data analysis (ANOVA) has been performed at the end to correlate the effects of these factors on strength. It is found that the strength of 3D printable geopolymer mortars is greatly influenced by its mix design and printing constraints.