International Research Journal of Engineering and Technology (IRJET)
e-ISSN: 2395-0056
Volume: 10 Issue: 05 | May 2023
p-ISSN: 2395-0072
www.irjet.net
3D Printable Concrete: Mixture Design, Simulation & Test Methods Jithin Sudhakrishnan1, Reshma Nair P J2, Manjusha Mathew3 1Mtech student, Structural and construction management, MGMCET, Pampakuda P.O, Muvattupuzha, Kerala, India 2Assistant professor, Civil Department, MGMCET, Pampakuda P.O, Muvattupuzha, Kerala, India 3Assistant professor, Civil Department, MGMCET, Pampakuda P.O, Muvattupuzha, Kerala, India
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Abstract – Over the past decade, 3D concrete printing has
under the gravitational load of already printed concrete layers above the printed layers without any support formwork. Compared to conventional concrete, 3DPC, as a keystone of a new, automatic, digital technology, brings numerous benefits to construction, like highly flexible architectural design, formwork-free fabrication, rapid construction, acceptable working conditions, material savings, etc. working conditions, material savings, etc. Cost efficiency also can be improved by this technology. Now the projects incorporating 3d printers are becoming recognized in the industry as an alternate technology in residential construction projects.3DPC has been successfully utilized in fabricating bridges, houses, bus stations, post offices and many other objects. Even though its rapid growing, we have only limited knowledge about this subject. For a successful extrusion process, the material must be flow able enough so that it can be extruded through the nozzle. But after the layer is extruded, the extruded layered concrete must have sufficient shear strength to resist deformation due to its superstructural weight & self-weight. Here thereby rheological parameters come in to play. The material must be fluid like with a low viscosity while inside the pump and nozzle, but once it’s extruded out this should change to a solid like behavior with enough strength to resist deformation. With respect to the material used, so many approaches can be used for achieving this. We know that in 3D printing of polymers (e.g., poly lactic acid (PLA)), this is achieved by a sudden change in temperature. While inside the nozzle, the filament made with polymer is heated to above its melting point, then allowing it to flow through the nozzle. But once extruded, it is rapidly allowed to cool and causing a transition to a solid state. For concrete and other non-Newtonian yield stress fluids, the fundamental principle is far different. The pump applies enough stress to exceed the yield stress of the material, allowing it to flow and extrude through the nozzle end. After extrusion is done, the high yield stress allows the material to resist deformation and prevent flow in the material. Also, it is noticed that yield stress of the extruded concrete increases with time. Therefore, yield stress of concrete is identified as an important parameter for mixture design of 3DPC. A high yield stress is required to prevent deformation of extruded layers. Apart from this, if the yield stress and plastic viscosity become very high such that they exceed the capability of the pump, then extrusion of the material becomes fail. So, there is an optimum range of yield stress in which the material is both extrudable and buildable is found out by researchers.
shown tremendous potential in the field of construction industry especially in the field of residential projects. The fresh stage and hardened state requirements of 3D printable concrete are not controlled by the present codes and standards. Even though the conventional 3D printing with PLA, ABS etc. are becoming popular and accessible in common market, the concept of 3D concrete printing is still inaccessible even to the scholars and researchers due to the high cost involved. So, we need to develop a cost-effective methodology for experimenting and testing of 3D printable concrete mixes. In this paper, various historical data on mix design proportions are studied and a general conclusion is made so that how a more acceptable mix can be made with the locally available materials in the market with proper granular material packing. A software called Elkem Material Mix Analyzer is used for the optimization of the mix. The concept of Manual Extrusion (Manual 3D printing with hand held extruder) is introduced here for experiment purpose. Aspects of mixture compositions and their effects on properties especially on fresh stage and hardened stage of 3DPC are highlighted and mix design approaches are described. Presently we are following a trial-and-error approach, and which remains the norm. We have to develop a standard guide line to achieve design targets common to specific parameters of 3D printer and which should be universally acceptable. Key Words: 3D printable concrete (3DPC), Rheological properties, Mix Design of printable concrete, Manual Extrusion, Material Mix Analyzer, Hand printing.
1.INTRODUCTION In 3D printing the concept followed is additive manufacturing technique. Normally the structure is built layer by layer based on three-dimensional computergenerated model. Khoshnevis has invented the contour crafting technique, which is found as the major mile stone in this sector. 3D concrete printing is now found as an innovative technology that shows amazing potential with regard to the increase of safety and productivity in construction. The main economically feasible concrete printing methods are based on layered extrusion. So we can say that 3D printable concrete (3DPC) is a “tailor-made” material that can be delivered by the concrete mixer and pump and adjustable extrusion nozzle of a 3D printer. And then after deposition, it should maintain its shape stability
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