Influence of nanoclay on the fresh and rheological behaviour of 3D printing mortar

Additive manufacturing is rapidly influencing the construction industry and designing good quality concrete for printing our homes remain a challenge. New materials are being tested for its suitability in a concrete mix. The purpose of this study is to investigate the influence of nanoclay (nC) on fresh and rheological properties of 3D printing concrete. The 3D printing concrete used in this study is prepared by mixing of cement (OPC), fly-ash (FA), basalt fibre (BA), nanoclay (nC) and superplasticizer (SP) with sand at constant water/cement ratio of 0.41. Fresh and rheological properties of this mixture is evaluated with the help of slump flow, cone penetration and cylindrical slump. The amount of nanoclay (nC) in the cementitious mixture is increased from zero to 6 kg/m3. Addition of nanoclay in the cementitious mixture for 3D printing concrete caused an important loss of workability but increased the yield stress of the material, which is attributed to higher cohesiveness of the mix. Adding more nanoclay (nC) in the cementitious mixture not only maintained the desired shape during and after extrusion, but also demonstrated more stable layers, which prevented it from collapsing under gravity and weight of the subsequent layers. A good linear correlation between slump flow, cone penetration test, yield stress and density of the material is established. The aesthetic effect of nanoclay on the cementitious mixture is demonstrated via the extrusion of layers utilising 3D printing mortar.