scholarly journals A Concise Review on Interlayer Bond Strength in 3D Concrete Printing

2021 ◽  
Vol 13 (13) ◽  
pp. 7137
Author(s):  
Adewumi John Babafemi ◽  
John Temitope Kolawole ◽  
Md Jihad Miah ◽  
Suvash Chandra Paul ◽  
Biranchi Panda
Keyword(s):  
Bond Strength ◽  
Critical Parameters ◽  
Printing Process ◽  
Interface Reactions ◽  
Current State ◽  
Concise Review ◽  
Established Fact ◽  
3D Printed ◽  
Key Aspects ◽  
Interlayer Bond

Interlayer bond strength is one of the key aspects of 3D concrete printing. It is a well-established fact that, similar to other 3D printing process material designs, process parameters and printing environment can significantly affect the bond strength between layers of 3D printed concrete. The first section of this review paper highlights the importance of bond strength, which can affect the mechanical and durability properties of 3D printed structures. The next section summarizes all the testing and bond strength measurement methods adopted in the literature, including mechanical and microstructure characterization. Finally, the last two sections focus on the influence of critical parameters on bond strength and different strategies employed in the literature for improving the strength via strengthening mechanical interlocking in the layers and tailoring surface as well as interface reactions. This concise review work will provide a holistic perspective on the current state of the art of interlayer bond strength in 3D concrete printing process.

scholarly journals Effect of Polypropylene Fibre Addition on Properties of Geopolymers Made by 3D Printing for Digital Construction

Materials ◽  
2018 ◽  
Vol 11 (12) ◽  
pp. 2352 ◽  
Author(s):  
Behzad Nematollahi ◽  
Praful Vijay ◽  
Jay Sanjayan ◽  
Ali Nazari ◽  
Ming Xia ◽  
...  
Keyword(s):  
3D Printing ◽  
Bond Strength ◽  
Fibre Volume ◽  
Interface Plane ◽  
Flexural Performance ◽  
Fresh State ◽  
Hardened State ◽  
3D Printed ◽  
Shape Retention ◽  
Interlayer Bond

This paper investigates the effect of polypropylene (PP) fibres on the fresh and hardened properties of 3D-printed fibre-reinforced geopolymer mortars. Different percentages of PP fibres ranging between 0.25% and 1.00% by volume were added to an optimised geopolymer mixture. All samples showed reasonable workability and extrudability. In addition, shape-retention ability in the fresh state was investigated as a major requirement for 3D-printing. The compressive strength of the printed specimens was tested in the hardened state in three loading directions, viz. longitudinal, perpendicular, and lateral. The flexural strength of samples was also tested in the longitudinal and lateral directions. In addition, the interlayer bond strength was investigated. Fibre addition seems to influence compressive strengths positively only when the loading is perpendicular to the interface plane. This is due to the preferential fibre alignment parallel to the direction of extrusion. The addition of fibre significantly enhanced the flexural performance of the printed samples. The use of fibre dosages of 0.75 and 1.00 vol % caused deflection-hardening behaviour of the 3D-printed geopolymers and, hence, a significantly higher fracture energy in comparison to specimens without fibre or with lower fibre content. However, an increase in the fibre volume caused some minor reduction in interlayer bond strength. With respect to properties in the fresh state, higher fibre volumes caused better shape-retention ability in the printed samples. The results indicate the possibility of printing fibre-reinforced geopolymers which meet all the necessary properties in both the fresh and hardened states.

scholarly journals Effect of Structural Build-Up on Interlayer Bond Strength of 3D Printed Cement Mortars

Materials ◽  
2021 ◽  
Vol 14 (2) ◽  
pp. 236
Author(s):  
Tinghong Pan ◽  
Yaqing Jiang ◽  
Hui He ◽  
Yu Wang ◽  
Kangting Yin
Keyword(s):  
Bond Strength ◽  
Surface Moisture ◽  
Cement Mortars ◽  
Nano Clay ◽  
3D Printed ◽  
Time Gap ◽  
The Relationship ◽  
Insight Into ◽  
Interlayer Bond ◽  
Operational Time

Understanding the relationship between the intrinsic characteristics of materials (such as rheological properties and structural build-up) and printability and controlling intrinsic characteristics of materials through additives to achieve excellent printability is vital in digital concrete additive manufacturing. This paper aims at studying the effects of material’s structural build-up on the interlayer bond strength of 3DPC with different time gaps. Structural build-up can indirectly affect the interlayer bond strength by affecting the surface moisture of concrete. Based on the structural build-up of 3DPC, a new parameter, maximum operational time (MOT), is proposed, which can be considered as the limit of time gap to ensure high interlayer bond strength. Slump-retaining polycarboxylate superplasticizer (TS) slightly slows down the physical flocculation rate, but increases the maximum operational time of the cement paste. Nano clay significantly increases the sort-term structural build-up rate and has the function of internal curing and water retaining. Composite with nano-clay and TS can reduce the loss of surface moisture of 3D printed layers, prevent the formation of interface weak layer, and increase the interlayer bond strength between printed layers. This contribution can provide new insight into the design of 3D-printed ink with good extrudability, outstanding buildability, and excellent interlayer bond strength.

scholarly journals Chloride Induced Corrosion and Carbonation in 3D Printed Concrete

2021 ◽  
Vol 7 (1) ◽  
pp. 1
Author(s):  
Jean De’M Malan ◽  
Algurnon Steve van Rooyen ◽  
Gideon P. A. G. van Zijl
Keyword(s):  
Carbon Dioxide ◽  
Flexural Strength ◽  
Bond Strength ◽  
Lack Of Fusion ◽  
Durability Properties ◽  
Chloride Induced Corrosion ◽  
3D Printed ◽  
Strength And Durability ◽  
Durability Performance ◽  
Interlayer Bond

The durability of reinforced concrete structures is dependent on the ability of the concrete cover to combat the ingress of chlorides and carbon dioxide in marine and urban environments. In recent years, interest in additive manufacturing), specifically referring to extrusion based three-dimensional concrete printing (3DCP), has been growing in the construction industry. Despite this being a promising technology that can save construction time, costs and resources, certain issues regarding the lack of fusion between subsequent printed layers have been brought to light. Research has shown that the lack of fusion at the interlayer regions can act as ingress pathways for corrosion contaminants, such as carbon dioxide and chloride aqueous solution, that can cause deterioration. This study investigates the interlayer bond strength (flexural strength) and durability performance of 3D printed concrete subjected to pass times between 0 and 30 min and compares the results to reference cast concrete of the same concrete mixture. The durability study includes Durability Index testing (oxygen permeability, water sorptivity and chloride conductivity index), accelerated concrete carbonation and chloride-induced corrosion. The results show that the cast samples outperform printed samples, yielding greater flexural strength and durability properties, and emphasize the importance of improving the 3DCP interfacial bond. Cast samples are shown to have randomly distributed, compact voids compared to the interconnected and elongated pores located at the interlayer regions of printed samples. In addition, printed samples yield lower interlayer bond strength and durability properties with an increase in pass time, which is attributed to surface moisture evaporation as well as the thixotropic behaviour of the concrete mixture. Good relationships between the mechanical strength and durability performance are also presented.

scholarly journals Dense ceramics with complex shape fabricated by 3D printing: A review

2021 ◽  
Author(s):  
Zhe Chen ◽  
Xiaohong Sun ◽  
Yunpeng Shang ◽  
Kunzhou Xiong ◽  
Zhongkai Xu ◽  
...  
Keyword(s):  
3D Printing ◽  
Complex Shape ◽  
Raw Materials ◽  
Three Dimensional ◽  
Critical Parameters ◽  
Printing Process ◽  
Practical Applications ◽  
3D Printing Technology ◽  
3D Printed ◽  
Ceramic Density

AbstractThree-dimensional (3D) printing technology is becoming a promising method for fabricating highly complex ceramics owing to the arbitrary design and the infinite combination of materials. Insufficient density is one of the main problems with 3D printed ceramics, but concentrated descriptions of making dense ceramics are scarce. This review specifically introduces the principles of the four 3D printing technologies and focuses on the parameters of each technology that affect the densification of 3D printed ceramics, such as the performance of raw materials and the interaction between energy and materials. The technical challenges and suggestions about how to achieve higher ceramic density are presented subsequently. The goal of the presented work is to comprehend the roles of critical parameters in the subsequent 3D printing process to prepare dense ceramics that can meet the practical applications.

Modelling the interlayer bond strength of 3D printed concrete with surface moisture

2021 ◽  
Vol 150 ◽  
pp. 106559
Author(s):  
Gerrit Marius Moelich ◽  
Jacques Kruger ◽  
Riaan Combrinck
Keyword(s):  
Bond Strength ◽  
Surface Moisture ◽  
3D Printed ◽  
Interlayer Bond

Investigations of process parameters during dissolution studies of drug loaded 3D printed tablets

2021 ◽  
pp. 095441192199358
Author(s):  
Varun Sharma ◽  
Khaja Moinuddin Shaik ◽  
Archita Choudhury ◽  
Pramod Kumar ◽  
Prateek Kala ◽  
...  
Keyword(s):  
Dissolution Rate ◽  
Process Parameters ◽  
Empirical Relation ◽  
Three Dimensional ◽  
Critical Parameters ◽  
Fused Deposition Modelling ◽  
Fused Deposition ◽  
Rate Of Dissolution ◽  
3D Printed ◽  
Percentage Release

The present research paper attempts to study the effect of different process parameters on the dissolution rate during 3D printed tablets. Three-dimensional printing has the potential of serving tailored made tablets to cater personalized drug delivery systems. Fluorescein loaded PVA filaments through impregnation route was used to fabricate tablets based on Taguchi based design of experimentation using Fused Deposition Modelling (FDM). The effect of print speed, infill percentage and layer thickness were analyzed to study the effect on rate of dissolution. Infill percentage followed by print speed were found to be critical parameters affecting dissolution rate. The data analysis provided an insight into the study of interaction among different 3D printing parameters to develop an empirical relation for percentage release of the drug in human body.

INNV-05. MULTIDISCIPLINARY SPINE ONCOLOGY CARE ACROSS THE DISEASE CONTINUUM - UPDATES FOR THE BEDSIDE AND THE BOARDS

2021 ◽  
Vol 23 (Supplement_6) ◽  
pp. vi106-vi106
Author(s):  
Erin Dunbar
Keyword(s):  
Initial Symptom ◽  
Multidisciplinary Program ◽  
Current State ◽  
Future State ◽  
Concise Review ◽  
Initial Tumor ◽  
Oncology Care ◽  
Resultant Increase ◽  
Tumor Types ◽  
Primary Spine

Abstract In response to the increased prevalence and complexity of metastatic and primary spine oncology, there has been a resultant increase in stakeholders, treatments and outcomes. A subset of the global multidisciplinary authors will present a timely and concise review of the contents of NOP’s Volume-7, supplement-1, “Multidisciplinary Spine Oncology Care Across the Disease Continuum”. The first portion will review: Epidemiology, Tumor Types, Presentation, Initial Tumor-directed Management, Initial Symptom-directed Management, Subsequent Tumor-directed Management, Subsequent Symptom-directed Management, and Multidisciplinary Program Development and Resources for Stakeholders. The second portion will challenge the current state of care and engage the attendees toward developing initiatives needed for a future state of care. Attendees will receive an update for both the bedside and the boards.

Delinquenzabbruch — Hauptaspekte des gegenwärtigen Forschungsstandes / Criminal Desistance — Key aspects from the current state of research

2016 ◽  
Vol 99 (2) ◽  
Author(s):  
Klaus Boers ◽  
Anna Mareike Herlth
Keyword(s):  
Current State ◽  
Criminal Desistance ◽  
State Of Research ◽  
Key Aspects

ZusammenfassungDie Annahme, dass die meisten Intensivtäter bis ins hohe Erwachsenenalter hinein aktiv bleiben, prägte in den 1980er und 1990er Jahren erneut die kriminologische Verlaufsforschung. Jedoch leiteten die 1993 von Laub und Sampson veröffentlichten Reanalysen der Gluecks- Daten, nach denen auch die meisten persistenten Delinquenzverläufe ab dem frühen Erwachsenenalter abgebrochen wurden, einen Paradigmenwechsel ein. Seitdem entwickelte sich der Delinquenzabbruch zu einem zentralen Bereich der kriminologischen Verlaufsforschung, der auch für die Kriminalpraxis sehr bedeutsam wurde. Denn es ist erfolgversprechender, einen künftigen Delinquenzabbruch zu unterstützen, als Ursachen anzugehen, die in der Regel vor dem Beginn der spätestens im Jugendalter einsetzenden Intensivdelinquenz liegen. Die meist empirisch untermauerte Diskussion um die Bedingungen des Delinquenzabbruchs drehte sich zunächst um den Vorrang entweder struktureller (Partnerbeziehungen, Arbeit) oder subjektiver (Wende zu einem konformen Selbstkonzept) Erklärungen. Sie konzentriert sich aktuell auf Konzeptionen, die diese beiden Aspekte integrieren. Neben solchen ätiologischen Ansätzen werden die einen Delinquenzabbruch eher erschwerenden formellen Kontrollinterventionen erst in neuerer Zeit stärker in den Blick genommen.

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