A. V. Rahul

A. V. Rahul
Ghent University | UGhent · Department of Structural Engineering

PhD
Postdoctoral researcher, Ghent University

About

24
Publications
15,965
Reads
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707
Citations
Citations since 2016
24 Research Items
699 Citations
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Introduction
A. V. Rahul is currently a postdoctoral researcher at the Magnel-Vandepitte laboratory, department of structural engineering, Ghent University, Belgium. His current research is on developing sustainable cementitious materials for the 3D printing of breakwater units. He finished his Ph.D. from IIT Madras, India.
Additional affiliations
January 2020 - present
Ghent University
Position
  • PostDoc Position
Education
July 2016 - December 2019
Indian Institute of Technology Madras
Field of study
  • Concrete 3D printing
June 2011 - June 2013
National Institute of Technology Karnataka
Field of study
  • Construction technology and management

Publications

Publications (24)
Article
This paper provides a comprehensive review of the material behaviour for extrusion-based concrete 3D printing spanning from the early age to long-term performance. We begin with a discussion on the recent progress on the understanding of early-age behaviour. Following this, the mechanical response in the hardened state, and the different strategies...
Article
3D printing with cementitious materials is an emerging technology and provides an active area of research. Despite this, there are only limited studies that examine the pumping behaviour of high yield stress fluids such as printable concrete. We present a study on the rheological behaviour of 3D printable cementitious materials with different aggre...
Article
In this paper, a Helmholtz-potential-based thermodynamic approach was developed for modelling fluids that exhibit both yielding and thixotropic behavior. The yielding behavior was captured using a framework of multiple natural configurations. The thixotropy was described using a structural parameter. The Helmholtz potential is made a function of a...
Article
The current study deals with a yield stress based mixture design approach for 3D printable concretes. The mixtures were evaluated based on buildability, extrudability, robustness and tests for structural build-up. For the print parameters (such as pump type, nozzle size and extrusion velocity) used in the study, it was found that both extrudability...
Article
This paper examines the printability of concrete formulations made using lightweight expanded clay aggregates (LECA) of maximum size 10 mm. The effect of coarse aggregate addition on the two essential aspects of printing, i.e., extrudability and buildability are examined using a piston-pump-based 3D printer system. The extrudability is assessed by...
Article
A twin-pipe pumping system has been developed to overcome the conflicting requirements in 3D concrete printing between pumping and deposition. In the twin-pipe pumping system, a helical static mixer, consisting of a series of mixing elements, is used to blend a cement-based mixture and a limestone-based mixture right before ex-trusion. As these two...
Article
To achieve stiffening control in 3D concrete printing, a twin-pipe pumping (TPP) system has been developed, where two streams of cementitious materials are pumped separately via two pumps and blended over a helical static mixer right before extrusion. However, in addition to the interlayer region, the presence of striations consisting of unmixed li...
Article
Enhanced structural build-up and strength development are crucial for various construction processes, especially in extrusion-based concrete 3D printing. However, controlling the stiffening process could be quite challenging as there are conflicting requirements during the pumping and deposition phase. We present a study to enhance the structural b...
Article
This study aims to interpret the early-stage rheology of alkali-activated slag (AAS) paste from microstructure perspectives. The microstructures visualized by cryogenic scanning electron microscopy (cryo-SEM) revealed the essential distinction between hydroxide and silicate-activated slag pastes. The hydroxide-based mixture showed typical suspensio...
Conference Paper
Extrusion-based 3D concrete printing is an emerging technology in the construction field due to the many advantages associated with it as compared to conventional mould casting technology. However, many aspects like durability and long-term service performance are yet to be investigated in detail. The present study focuses on understanding the salt...
Article
Extrusion-based concrete 3D printing is a promising technology and has the potential for being a sustainable construction solution by utilizing structural optimization and reduced material usage. However, studies focusing on the sustainability assessment of 3D printable concrete mixtures are not many. In the current study, a quantitative assessment...
Article
To tackle the conflicts between the pumping and deposition process in 3D concrete printing, a twin-pipe pumping (TPP) system with a helical static mixer can be used. In this way, a cement-based mixture (without accelerator) and a limestone powder-based mixture (with a high dosage of accelerator) are transported separately and mixed within the helic...
Article
In the current study, we examine the influence of natural and recycled coarse aggregates on the rheological, mechanical and shrinkage behaviour of 3D printable concrete. The rheological properties were analyzed using a dynamic shear rheometer, and it was observed that the addition of coarse aggregates significantly decreased the yield stress and ma...
Article
Full-text available
This paper explores the sustainability aspects of binders used in concrete 3D concrete printing. Firstly, a prospective approach to conduct sustainability assessment based on the life cycle of 3D printed structures is presented, which also highlights the importance of considering the functional requirements of the mixes used for 3D printing. The po...
Article
Full-text available
Similar to conventional cast concrete, printable materials require reinforcement to counteract their low tensile strength. However, as traditional reinforcement strategies are not commonly used in 3D print applications, fiber reinforcement can serve as an alternative. This study aims to assess the influence of different polypropylene fiber lengths...
Article
Calcium sulfoaluminate (CSA) cement is one of the promising low-CO2 alternate binder systems that could replace Portland cement in a variety of applications. In the current study, the feasibility of using CSA cement as a binder for 3D printable concrete was investigated. Very short open time due to the rapid hydration and high plastic viscosity are...
Article
Full-text available
Porosity of a mortar significantly influences its mechanical characteristics as well as durability. To ensure compatibility while designing a repair mortar for historic masonry, it is important to have both a qualitative and quantitative description of the pore structure. In this paper, we present the porosity investigations of two types of historic...
Article
In many applications such as grouting, shotcrete, and 3D concrete printing, conflicting material requirements exist between the transportation and fabrication process, as fresh materials should be pumped easily with a low stiffening rate and a high fluidity while a rapid strength gain must occur after placement. In such applications, it is therefor...
Article
Full-text available
This paper provides a review of the development of digital fabrication methods in the construction industry and academia, with a major emphasis on extrusion-based 3D printing. A detailed description of the work done by the research group in IIT Madras in developing a Portland cement-based 3D printable formulation is discussed. Finally, the areas in...
Article
A rapid and reliable performance test will enable fast and suitable selection of binder for each service environment. In order to evaluate the possibility of using smaller specimens to accelerate the sulphate resistance tests, Portland cement mortar specimens of sizes 20 × 20 × 160 mm, 25 × 25 × 280 mm and 40 × 40 × 160 mm were continuously immerse...
Conference Paper
3D concrete printing technology has gained huge momentum in the past two decades. The enhanced geometric freedom associated with 3D concrete printing could be beneficial for a variety of applications. However, the relatively high binder content in 3D printable concrete makes them less sustainable compared to mould-cast concrete. Therefore, developi...
Article
A critical criterion for the extrusion of cementitious materials is that the mix used must remain stable and homogeneous without undergoing phase separation. Therefore, it is important to have an assessment of water retention capacity of mortars to be used for such purposes. Although there are empirical methods like bleed test (ASTM C1741 – 18), th...
Article
The current study deals with test methods for characterizing the mechanical behaviour of 3D printed wall elements. At first, the effect of interfaces present in a printed concrete element was examined through an assessment of porosity and bond shear test. The porosity was evaluated using specimens extracted from the bulk as well as from the interfa...

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Projects

Projects (3)
Archived project
- A thermodynamic framework for modelling the yielding and thixotropic behaviour - A thermodynamic framework for describing the early age structural build-up due to hydration - Modelling the creep-recovery response of cement-based materials - Experimental corroborations
Project
- Development of sustainable cementitious materials for 3D printing - Durability assessment of printable concrete for marine environment
Archived project
- Mixture design and rheological characterization of 3D printable concrete - Mechanical characterization of printable concrete