scholarly journals Effect of Curing Methods on Shrinkage Development in 3D-Printed Concrete

Materials ◽  
2020 ◽  
Vol 13 (11) ◽  
pp. 2590 ◽  
Author(s):  
Karol Federowicz ◽  
Maria Kaszyńska ◽  
Adam Zieliński ◽  
Marcin Hoffmann
Keyword(s):  
Original Method ◽  
Innovative Technology ◽  
Strength Development ◽  
Shrinkage Reducing Admixture ◽  
Curing Methods ◽  
Technological Developments ◽  
3D Printers ◽  
3D Printed ◽  
Shrinkage Reducing Admixtures ◽  
Concrete Elements

Technological developments in construction have led to an increase in the use of 3D modelling using CAD environments. The popularity of this approach has increased in tandem with developments in industry branches which use 3D printers to print concrete based printing materials in construction, as these allow freedom in shaping the dimensions of supporting elements. One of the biggest challenges for researchers working on this highly innovative technology is that of cement material shrinkage. This article presents the findings of research on an original method of measuring deformations caused by shrinkage in 3D-printed concrete elements. It also discusses the results of tests on base mixes, as well as comparisons between the influence of internal and external curing methods on the development of deformations and their final outcomes. Furthermore, the article discusses differences between deformations formed after seven days of hardening without curing, with those which occur when two common, traditional concrete curing methods are used: foil insulation and shrinkage reducing admixtures. In addition, the article examines the effects of internal curing on the 1, 7, 14, 21 and 28 day mechanical properties of concrete, in accordance with EN 196-1 and EN 12390-2. Studies have shown that the optimal amount of shrinkage reducing admixtures is 4% (in relation to the mass of cement), resulting in a reduction in total shrinkage of 23%. The use of a shrinkage reducing admixture in 3D-printed concrete does not affect their strength after 28 days, but slows the strength development during the first 7 days.

scholarly journals The role of shrinkage reducing admixtures and supplementary cementitious materials in volume stability and strength development

2019 ◽  
Vol 289 ◽  
pp. 02005
Author(s):  
Ioanna Papayianni ◽  
Fotini Kesikidou ◽  
Philip Henes Alt
Keyword(s):  
Cementitious Materials ◽  
Supplementary Cementitious Materials ◽  
Strength Development ◽  
Capillary Absorption ◽  
Volume Stability ◽  
Cement Mortars ◽  
Shrinkage Reducing Admixture ◽  
Binder Ratio ◽  
Shrinkage Reducing Admixtures ◽  
Water To Binder Ratio

Shrinkage is one of the main reasons for mortar and concrete failures like curling, crack formation and de-bonding. It is a complex phenomenon due to many factors involved, such as the type and amount of cement, water to binder ratio, binder to aggregates ratio and the type and granulometry of the aggregates, relative humidity, air temperature and the temperature of concrete. To reduce this phenomenon, Shrinkage Reducing Admixtures (SRAs) have been studied over the last 30 years. On the other hand, investigation in the field of Supplementary Cementitious Materials (SCMs) has indicated that their use in concrete may improve its volume stability depending on their percentage and the type of the material. In this paper, the addition of a Shrinkage Reducing Admixture and Supplementary Cementitious Materials like ladle furnace slag, calcareous fly ash and limestone filler, were investigated. Their influence, separately and in combination, in volume stability and strength development of cement mortars was identified. Capillary absorption and open porosity were also determined.

scholarly journals Evaluation of the Circularity of Recycled PLA Filaments for 3D Printers

2020 ◽  
Vol 10 (24) ◽  
pp. 8967
Author(s):  
Victor Gil Muñoz ◽  
Luisa M. Muneta ◽  
Ruth Carrasco-Gallego ◽  
Juan de Juanes Marquez ◽  
David Hidalgo-Carvajal
Keyword(s):  
Circular Economy ◽  
Protective Equipment ◽  
Fused Filament Fabrication ◽  
Circular Loop ◽  
Material Supply ◽  
3D Printers ◽  
3D Printed ◽  
Circular Economics ◽  
High Level ◽  
Additional Value

The circular economy model offers great opportunities to companies, as it not only allows them to capture additional value from their products and materials, but also reduce the fluctuations of price-related risks and material supply. These risks are present in all kind of businesses not based on the circular economy. The circular economy also enables economic growth without the need for more resources. This is because each unit has a higher value as a result of recycling and reuse of products and materials after use. Following this circular economics framework, the Polytechnic University of Madrid (Universidad Politécnica de Madrid, UPM) has adopted strategies aimed at improving the circularity of products. In particular, this article provides the result of obtaining recycled PLA filament from waste originating from university 3D FFF (fused filament fabrication) printers and waste generated by “Coronamakers” in the production of visors and parts for PPEs (Personal Protective Equipment) during the lockdown period of COVID-19 in Spain. This filament is used in the production of 3D printed parts that university students use in their classes, so the circular loop is closed. The obtained score of Material Circularity Indicator (MCI) of this material has been calculated, indicating its high level of circularity.

Designing Inclusion: Using 3D Printing to Maximize Adapted Physical Education Participation

2021 ◽  
pp. 004005992110101
Author(s):  
A. Chloe Simpson ◽  
Andrea Ruth Taliaferro
Keyword(s):  
3D Printing ◽  
Student Success ◽  
Assistive Technology ◽  
Adapted Physical Education ◽  
Physical Educators ◽  
Related Service ◽  
3D Printers ◽  
3D Printed ◽  
Education Participation ◽  
Individual Design

While assistive technology is often suggested as a way to increase, maintain, or improve functional ability for individuals with disabilities within physical activity (PA) settings, cost and availability of such items are often noted as barriers. In recent years, 3D printing has become available to the general public through the adoption of 3D printers in schools, libraries, and universities. Through individual design and rapid prototyping, 3D printing can support physical educators in accommodating student need for assistive technology through a multitude of modification possibilities. This article will highlight the capacity for 3D printed assistive technology within educational settings, and will illustrate how teachers, APE specialists, and other related service personnel can utilize this technology to support student success in PE and PA settings. This article will also assist practitioners with locating, uploading, and utilizing existing collections of 3D assistive technology models from open-source websites, such as Thingiverse.

scholarly journals Evaluation of the Ability to Accurately Produce Angular Details by 3D Printing of Plastic Parts

Machines ◽  
2021 ◽  
Vol 9 (8) ◽  
pp. 150
Author(s):  
Andrei Marius Mihalache ◽  
Gheorghe Nagîț ◽  
Laurențiu Slătineanu ◽  
Adelina Hrițuc ◽  
Angelos Markopoulos ◽  
...  
Keyword(s):  
3D Printing ◽  
Point Of View ◽  
Vertex Angle ◽  
Function Type ◽  
Constant Height ◽  
3D Printers ◽  
3D Printed ◽  
Mathematical Processing ◽  
Plastic Parts

3D printing is a process that has become widely used in recent years, allowing the production of parts with relatively complicated shapes from metallic and non-metallic materials. In some cases, it is challenging to evaluate the ability of 3D printers to make fine details of parts. For such an assessment, the printing of samples showing intersections of surfaces with low angle values was considered. An experimental plan was designed and materialized to highlight the influence of different factors, such as the thickness of the deposited material layer, the printing speed, the cooling and filling conditions of the 3D-printed part, and the thickness of the sample. Samples using areas in the form of isosceles triangles with constant height or bases with the same length, respectively, were used. The mathematical processing of the experimental results allowed the determination of empirical mathematical models of the power-function type. It allowed the detection of both the direction of actions and the intensity of the influence exerted by the input factors. It is concluded that the strongest influence on the printer’s ability to produce fine detail, from the point of view addressed in the paper, is exerted by the vertex angle, whose reduction leads to a decrease in printing accuracy.

Assessment of the accuracy of 3D printed teeth by various 3D printers in forensic odontology

2021 ◽  
pp. 111044
Author(s):  
Abraham Johnson ◽  
Gargi Jani ◽  
Rachel Carew ◽  
Astha Pandey
Keyword(s):  
Forensic Odontology ◽  
3D Printers ◽  
3D Printed

scholarly journals Flexible 3D Printed Molds for Educational Use. Digital Fabrication of 3D Typography

2019 ◽  
Vol 15 (13) ◽  
pp. 4 ◽  
Author(s):  
Alejandro Bonnet De León ◽  
Jose Luis Saorin ◽  
Jorge De la Torre-Cantero ◽  
Cecile Meier ◽  
María Cabrera-Pardo
Keyword(s):  
3D Modeling ◽  
Low Cost ◽  
Digital Fabrication ◽  
3D Printer ◽  
School Environments ◽  
Flexible Material ◽  
Educational Environments ◽  
3D Printers ◽  
3D Printed ◽  
The Subject

<p class="0abstract"><span lang="EN-US">One of the drawbacks of using 3D printers in educational environments is that the creation time of each piece is high and therefore it is difficult to manufacture at least one piece for each student. This aspect is important so that each student can feel part of the manufacturing process. To achieve this, 3D printers can be used, not to make pieces, but to make the molds that students use to create replicas. On the other hand, for a mold to be used to make several pieces, it is convenient to make it with flexible material. However, most used material for 3D printers (PLA) is very rigid. To solve this problem, this article designs a methodology that allows the use of low-cost 3D printers (most common in school environments) with flexible material so that each mold can be used to manufacture parts for several students. To print flexible material with low-cost printers, it is necessary to adapt the machine and the print parameters to work properly. This article analyzes the changes to be made with a low cost 3D printer and validates the use of molds in school environments. A pilot test has been carried out with 8 students of the subject of Typography, in the School of Art and Superior of Design of Tenerife. During the activity, the students carried out the process of designing a typography and creating digital molds for 3D printing with flexible material. The designs were made using free 3D modeling programs and low-cost technologies.</span></p>

scholarly journals Development of 3D Printed Networks in Self-Healing Concrete

Materials ◽  
2020 ◽  
Vol 13 (6) ◽  
pp. 1328 ◽  
Author(s):  
Cristina De Nardi ◽  
Diane Gardner ◽  
Anthony Duncan Jefferson
Keyword(s):  
Vascular System ◽  
Physical And Mechanical Properties ◽  
Self Healing ◽  
Vascular Networks ◽  
Minimal Impact ◽  
Cementitious Matrix ◽  
Healing Agent ◽  
3D Printed ◽  
Series Of Experiments ◽  
Concrete Elements

This paper presents a new form of biomimetic cementitious material, which employs 3D-printed tetrahedral mini-vascular networks (MVNs) to store and deliver healing agents to damage sites within cementitious matrices. The MVNs are required to not only protect the healing agent for a sufficient period of time but also survive the mixing process, release the healing agent when the cementitious matrix is damaged, and have minimal impact on the physical and mechanical properties of the host cementitious matrix. A systematic study is described which fulfilled these design requirements and determined the most appropriate form and material for the MVNs. A subsequent series of experiments showed that MVNs filled with sodium silicate, embedded in concrete specimens, are able to respond effectively to damage, behave as a perfusable vascular system and thus act as healing agent reservoirs that are available for multiple damage-healing events. It was also proved that healing agents encapsulated within these MVNs can be transported to cracked zones in concrete elements under capillary driving action, and produce a recovery of strength, stiffness and fracture energy.

scholarly journals Effect of Shrinkage Reducing Admixture on Drying Shrinkage of Concrete with Different w/c Ratios

Materials ◽  
2020 ◽  
Vol 13 (24) ◽  
pp. 5721 ◽  
Author(s):  
Mahdi Kioumarsi ◽  
Fazel Azarhomayun ◽  
Mohammad Haji ◽  
Mohammad Shekarchi
Keyword(s):  
Autogenous Shrinkage ◽  
Drying Shrinkage ◽  
Hardened Concrete ◽  
Free Shrinkage ◽  
Water Penetration ◽  
Concrete Shrinkage ◽  
Different Types ◽  
Shrinkage Reducing Admixture ◽  
Shrinkage Reducing Admixtures ◽  
Liquid Propylene

The reduction of the moisture content of concrete during the drying process reduces the concrete’s volume and causes it to shrink. In general, concrete shrinkage is a phenomenon that causes concrete volume to dwindle and can lead to durability problems. There are different types of this phenomenon, among them chemical shrinkage, autogenous shrinkage, drying shrinkage including free shrinkage and restrained shrinkage, and thermal contraction. Shrinkage-reducing admixtures are commercially available in different forms. The present study investigates the effect of liquid propylene glycol ether on mechanical properties and free shrinkage induced by drying at different water-cement (w/c) ratios. Furthermore, the effect of shrinkage-reducing admixtures on the properties of hardened concrete such as compressive and tensile strength, electrical resistivity, modulus of elasticity, free drying shrinkage, water absorption, and depth of water penetration was investigated. The results indicated that shrinkage reducing agents performed better in a low w/c ratio and resulted in up to 50% shrinkage reduction, which was due to the surface reduction of capillary pores. The prediction of free shrinkage due to drying was also performed using an artificial neural network.

Simulation and practice of particle inertial focusing in 3D-printed serpentine microfluidic chips via commercial 3D-printers

Soft Matter ◽  
2020 ◽  
Vol 16 (12) ◽  
pp. 3096-3105
Author(s):  
Pengju Yin ◽  
Lei Zhao ◽  
Zezhou Chen ◽  
Zhiqiang Jiao ◽  
Hongyan Shi ◽  
...  
Keyword(s):  
Microfluidic Chips ◽  
Inertial Focusing ◽  
Particle Focusing ◽  
3D Printers ◽  
3D Printed

Inertial microfluidic chips were fabricated using commercial 3D-printers and the particle focusing was implemented in channels.

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