Date of Award
Master of Science
Industrial and Manufacturing Systems Engineering
The need to automate the construction process for civil infrastructures has been perpetually propelled by the reported number of detrimental site accidents, enormous time, and material wastages in the current labor-intensive approaches. Additive 3D printing applications in the construction sector could revolutionize the construction sites. The 3D printing technologies will be an eco-friendly variant and will relax the formwork requirement, giving wider build customizability when compared to the traditional construction methods. The notable advantages of 3D printing over conventional construction techniques include safer work ambiance, reduced cost and time for construction.
The first objective of this research work is to identify the concrete mixture that is readily available for 3D printing and establish their material characteristics. This work serves up a model schema for researchers to look up and identify desired mixture properties for instantaneous concrete printing. In this study, ready-to-print fresh cementitious mixtures were characterized for printability and buildability based on their rheological and mechanical properties. Admixtures such as Silica fume and Superplasticizer were added to the ordinary Portland cement in different proportions to test and improve the yield stress and attain the desired viscosity for 3D printing.
The other objective is to study the impacts of using different nozzle geometries in the printed constructs. In the additive 3D printing process, choosing the right nozzle geometry before printing is critical as it affects the surface finish as well as the mechanical properties of the constructs. This study utilizes point cloud data of the printed samples obtained from Structured Light System- a scanning technique to measure the contour deviation and surface roughness. The compression strength of the mixtures was determined to explore the mechanical properties, by conducting compression tests as per the ASTM standards. A comparative study on the compression strength of 3D printed constructs with precast was made to identify the impacts of nozzle geometry in the compression strength.
To summarize, a concrete extrusion system has been built and the concrete flow properties that are desirable for instantaneous 3D printing have been identified. The rheological properties, printability, and buildability of all the identified concrete mixtures were evaluated and the best mixture proportions were advanced for printing constructs. The nozzle geometry study has established the impacts on the contour as well as the mechanical properties on the constructs, and hence urging the need to choose the right nozzle geometry before 3D printing.
Karthick Manikandan Gopalakrishnan Deivanai
Gopalakrishnan Deivanai, Karthick Manikandan, "Additive printing for civil infrastructure: Assessing concrete mix design, printability and nozzle effects" (2020). Graduate Theses and Dissertations. 17937.