Comparative evaluation of rheological models for 3D printable concrete Prabhat Ranjan Prem ⇑ , Darssni Ravichandran, Senthil Kumar Kaliyavaradhan, P.S. Ambily Advanced Materials Laboratory, CSIR-Structural Engineering Research Centre, Chennai, Tamil Nadu, 600113, India article info Article history: Available online 27 April 2022 Keywords: 3D printing Rheology Models Nanosilica (NS) Poly-vinyl Alcohol fiber (PVA) Fly Ash abstract The study investigates different rheology models and examines the effect of dosage of different building materials in a 3D printable mix to achieve the desired rheology. The rheological properties of (i) Nano silica (NS), ii) Poly-vinyl Alcohol (PVA) fiber, and (iii) Class F - Fly ash are examined in the current study. The popular rheology models such as Bingham Model, Herschel-Bulkley model, and Power-law model are comparatively studied with the experimentally obtained rheological properties. Based on the study, it is found that the rheological parameters such as yield stress (Pa), Plastic viscosity (Pa.s), Power-law expo- nent, and consistency or flow co-efficient obtained from the aforementioned models are coherent with the experimental observations. Copyright Ó 2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Confer- ence on Advances in Construction Materials and Structures. 1. Introduction Globally construction industry accounts for 6% of world GDP and is expected to achieve 14.7% world GDP by 2030. However, it is found that construction sector productivity has increased by only 1% over the past 20 years [1]. This is majorly due to construc- tion being manual, skilled workforce shortages, strength develop- ment time, formwork construction, formwork removal time, and conservative approaches to adopt new technologies [2–3]. The cur- rent industrial revolution (Industry 4.0), offers Additive manufac- turing (AM) technology, which if integrated with traditional construction, can cause a positive disruptive transformation in terms of cost scientific, technological and societal impact. Stere- olithography, fused deposition modeling, inkjet powder printing, contour crafting (CC), selective laser sintering, and selective heat- ing sintering are some of the techniques employed in the AM industry. The CC is found to be more suitable for structural con- struction and coined as Concrete 3D printing (C3DP) [4]. In C3DP technology, the structure is modeled in computer-aided design software and converted to 3D geometries. Further, the model is linked to machine controls using G-code which commands the rotation and translation of the printer arm connected to a mixer pump. Cementitious paste, mortar, or concrete are extruded from the pumping nozzle and are vertically built on printed layers. Since 2015, interest and research on C3DP have undergone a paradigm shift. Selection of new and alternative printing materials, mix com- position and design, development and modeling of printability indicators, evaluation of fresh and hardened properties are the most frequently investigated topics in C3DP [5]. It is important to note that the design criteria for selecting mix and materials for routine construction practices [15] cannot be implemented in C3DP, due to inadequate rheological and stiffening behavior. For the case of C3DP, the challenges in the fresh state include available time for material extrusion and pumping (open time), setting dura- tion, printing time, building rate, deformation, distortion, and buckling under self-weight rheological properties and quality control. The issues in the hardened states are interlayer bond strength, bulk density, under-filling, tension reinforcement, creep, shrinkage during hydration, durability, and measurement techniques of hardened material properties [6 –7]. In view of the same, one critical param- eter known as the rheology of C3DP is addressed in the current research. In the paper, first, a brief background on existing linear and non-linear rheology models is presented. Second, the materials employed in the literature for concrete 3D printing are identified, and information regarding the shear rate and shear stress are stud- ied. Next, the effect of dosage on identified materials of concrete 3D printing is studied using experimental data and existing rheol- ogy models. https://doi.org/10.1016/j.matpr.2022.04.555 2214-7853/Copyright Ó 2022 Elsevier Ltd. All rights reserved. Selection and peer-review under responsibility of the scientific committee of the International Conference on Advances in Construction Materials and Structures. ⇑ Corresponding author. E-mail address: prabhat@serc.res.in (P. Ranjan Prem). Materials Today: Proceedings 65 (2022) 1594–1598 Contents lists available at ScienceDirect Materials Today: Proceedings journal homepage: www.elsevier.com/locate/matpr