An ab initio approach for thixotropy characterisation of (nanoparticle-infused) 3D printable concrete: Fid-Bau Portal

An ab initio approach for thixotropy characterisation of (nanoparticle-infused) 3D printable concrete

Kruger, Jacques / Zeranka, Stephan / van Zijl, Gideon

Highlights • Rthix, the re-flocculation rate, is up to one order of magnitude larger than Athix. • Addition of an optimum quantity nano-silica increases thixotropy. • Optimum superplasticizer dosage improves thixotropy behaviour. • Nano-silica addition improves material buildability for 3D concrete printing.

Abstract This paper presents a novel rheological thixotropy model that specifically appertains to the characterisation of materials that are suitable for 3D printing of concrete (3DPC). The model accounts for both physical and chemical influences on a material’s microstructure, denoted by $R_{t h i x}$ (re-flocculation) and $A_{t h i x}$ (structuration) respectively. Rheological analyses are performed on a reference material with varying superplasticizer (SP) and nano-silica (nS) dosages in order to determine their effects on the aforementioned parameters. Specific focus is placed on the re-flocculation thixotropy mechanism. The advantages of adding nanoparticles to concrete for 3DPC is practically validated by printing circular hollow columns until failure occurs. The result is supported by the thixotropy model, which is applied to the materials that are used for the 3DPC tests. It is concluded that, for this study, $R_{t h i x}$ is a better measure of thixotropy behaviour that is suitable for 3DPC than $A_{t h i x}$ .