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Title:Effect of vibration on yield stress of concrete for 3D printing applications
Author(s):Pattaje Sooryanarayana, Karthik
Advisor(s):Lange, David A.
Department / Program:Civil & Environmental Eng
Discipline:Civil Engineering
Degree Granting Institution:University of Illinois at Urbana-Champaign
Subject(s):Concrete, 3D Printing, Vibration, Yield stress, ICAR rheometer
Abstract:Concrete 3D printing is one of the latest developments in the field of construction. It promises several benefits but needs further development before it can be used as a practical construction technique. One primary challenge is the requirement for 3D printable concrete to behave like a fluid during pumping and extrusion, and like a solid after extrusion. This paradox could potentially be solved by using vibration to control the yield stress of concrete. Research has shown that concrete behaves like a Newtonian fluid during vibration at low shear rates. The primary objective of this research is to qualitatively understand the effects of vibration on the fresh properties of concrete and its implications for 3D printing with a vibrating nozzle. An existing concrete rheometer was modified to be able to reliably measure yield stress of concrete during vibration. This thesis details the modifications made to the rheometer and discusses the reliability of the measurements made with the modified rheometer. The relationship between yield stress and time was evaluated and the effect of the destructive yield stress measurement technique on its result was discussed. A test protocol was developed to mimic concrete 3D printing using vibration. The parabolic relationship between yield stress and sand content was verified at different hydration ages using the developed test protocol. The effect of vibration on the yield stress of concrete during the dormant stage was studied. The reduction in yield stress during vibration was found to be instantaneous and reversible throughout the dormant period. It was also found out that vibration causes the yield stress of concrete to grow at a slower pace. It was also observed that the effect of vibration on concrete is dependent on the amplitude of vibration.
Issue Date:2018-07-19
Rights Information:Copyright 2018 Karthik Pattaje Sooryanarayana
Date Available in IDEALS:2018-09-27
Date Deposited:2018-08

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