scholarly journals The Effect of Material Fresh Properties and Process Parameters on Buildability and Interlayer Adhesion of 3D Printed Concrete

Materials ◽  
2019 ◽  
Vol 12 (13) ◽  
pp. 2149 ◽  
Author(s):  
Biranchi Panda ◽  
Nisar Ahamed Noor Mohamed ◽  
Suvash Chandra Paul ◽  
GVP Bhagath Singh ◽  
Ming Jen Tan ◽  
...  
Keyword(s):  
Bond Strength ◽  
Process Parameters ◽  
Control Sample ◽  
Cementitious Materials ◽  
Nano Particles ◽  
High Yield ◽  
Adhesion Properties ◽  
Low Viscosity ◽  
Main Challenge ◽  
3D Printed

The advent of digital concrete fabrication calls for advancing our understanding of the interaction of 3D printing with material rheology and print parameters, in addition to developing new measurement and control techniques. Thixotropy is the main challenge associated with printable material, which offers high yield strength and low viscosity. The higher the thixotropy, the better the shape stability and the higher buildability. However, exceeding a minimum value of thixotropy can cause high extrusion pressure and poor interface bond strength if the printing parameters are not optimized to the part design. This paper aims to investigate the effects of both material and process parameters on the buildability and inter-layer adhesion properties of 3D printed cementitious materials, produced with different thixotropy and print head standoff distances. Nano particles are used to increase the thixotropy and, in this context, a lower standoff distance is found to be useful for improving the bond strength. The low viscosity “control” sample is unaffected by the variation in standoff distances, which is attributed to its flowability and low yield stress characteristics that lead to strong interfacial bonding. This is supported by our microscopic observations.

scholarly journals New water-based flexographic ink based on new ter-polymer nano-particles as eco-friendly binders – Part II

2020 ◽  
Vol 49 (6) ◽  
pp. 473-482
Author(s):  
H. Abd El-Wahab ◽  
G.A. Meligi ◽  
M.G. Hassaan ◽  
L. Lin
Keyword(s):  
Water Resistance ◽  
Low Cost ◽  
Thermo Gravimetric Analysis ◽  
Gel Permeation Chromatography ◽  
Nano Particles ◽  
Gravimetric Analysis ◽  
Adhesion Properties ◽  
Content Type ◽  
Low Viscosity ◽  
Water Based

Purpose The purpose of this study is to prepare, characterise and evaluate nano-emulsions of ter-polymers of various compositions as eco-friendly binders for flexographic ink industry. Design/methodology/approach Various nano-emulsions of ter-polymers were prepared based on Vinyl acetate, Vinyl Versatate, butyl acrylate, acrylic acid and acrylamide monomers by means of a conventional seeded emulsion polymerisation technique, using K2S2O8 as the initiator. The characterisation of the prepared emulsions was performed using Fourier transform infrared, thermo-gravimetric analysis, gel permeation chromatography and transmission electron microscopy. A selection of co-polymers and ter-polymers were formulated with pigments and additional ingredients, as water-based flexographic inks. The inks were characterised for their rheological properties, pH, degree of dispersion, water-resistance and colour density. Findings It was found that the low viscosity of the prepared polymers may reduce the film thickness of the flexographic inks and may also increase the spreading of the ink on the surface. As a result, stable modified poly acrylate-based latex with improved physico-mechanical properties was obtained. The prepared latexes showed improved properties such as enhanced thermal stability and better water resistance. The effect of the emulsifier type on the properties of the resulting emulsion latexes and their corresponding films were investigated. Also, as the hydrophobic monomer increases, so does the colour density and increasing the binder ratio enhances the gloss values. The improving in gloss values were obtained and provide excellent adhesion properties for both the pigment particles and the base paper. Research limitations/implications The study focusses on the preparation of new water-based ter-polymer nano-particles and their use as eco-friendly binders for flexographic ink industry. Ink formulations based on other different type emulsion polymers could also be studied to assess the applicability of the ink formulation system found for other binders. Practical implications The ink formulations developed could find use in industrial-scale printing. Originality/value Eco-friendly environment and low-cost ink formulations for printing on paper substrates are novel.

Effect of Type of Fiber on Inter-Layer Bond and Flexural Strengths of Extrusion-Based 3D Printed Geopolymer

2018 ◽  
Vol 939 ◽  
pp. 155-162 ◽  
Author(s):  
Behzad Nematollahi ◽  
Ming Xia ◽  
Jay Sanjayan ◽  
Praful Vijay
Keyword(s):  
Flexural Strength ◽  
Bond Strength ◽  
Fused Deposition Modeling ◽  
Shear Failure ◽  
Cementitious Materials ◽  
Tensile Failure ◽  
Layer By Layer ◽  
Fused Deposition ◽  
Rate Of Increase ◽  
3D Printed

Extrusion-based 3D concrete printing is analogous to fused deposition modeling method, which extrudes cementitious materials from a nozzle to build a complex concrete structure layer-by-layer without the use of expensive formwork. This study aims to investigate the influence of type of fiber on inter-layer bond strength and flexural strength of extrusion-based 3D printed geopolymer. An extrudable fly ash-based geopolymer composition previously developed by the authors was reinforced by three types of fibers, namely polyvinyl alcohol (PVA), polypropylene (PP) and polyphenylene benzobisoxazole (PBO) fibers. Control geopolymer specimens with no fiber were also 3D printed for comparison purposes. The results indicated that the incorporation of fibers reduced the inter-layer bond strength of 3D printed geopolymer. This pattern was true regardless of the type of fiber. On the other hand, the flexural strength of 3D printed fiber-reinforced geopolymer mixtures was substantially higher than that of the 3D printed geopolymer with no fiber. The rate of increase in the flexural strength depended on the type of fiber. The flexural failures of the specimens were due to the tensile failure of the bottom layer, rather than the shear failure of the interfaces.

scholarly journals Microstructural Characterization of 3D Printed Cementitious Materials

Materials ◽  
2019 ◽  
Vol 12 (18) ◽  
pp. 2993 ◽  
Author(s):  
Jolien Van Der Putten ◽  
Maxim Deprez ◽  
Veerle Cnudde ◽  
Geert De Schutter ◽  
Kim Van Tittelboom
Keyword(s):  
Process Parameters ◽  
Mechanical Performance ◽  
Three Dimensional ◽  
Microstructural Characterization ◽  
Lower Surface ◽  
Cementitious Materials ◽  
Lower Amount ◽  
Time Interval ◽  
3D Printed ◽  
Printing Speed

Three-dimensional concrete printing (3DCP) has progressed rapidly in recent years. With the aim to realize both buildings and civil works without using any molding, not only has the need for reliable mechanical properties of printed concrete grown, but also the need for more durable and environmentally friendly materials. As a consequence of super positioning cementitious layers, voids are created which can negatively affect durability. This paper presents the results of an experimental study on the relationship between 3DCP process parameters and the formed microstructure. The effect of two different process parameters (printing speed and inter-layer time) on the microstructure was established for fresh and hardened states, and the results were correlated with mechanical performance. In the case of a higher printing speed, a lower surface roughness was created due to the higher kinetic energy of the sand particles and the higher force applied. Microstructural investigations revealed that the amount of unhydrated cement particles was higher in the case of a lower inter-layer interval (i.e., 10 min). This phenomenon could be related to the higher water demand of the printed layer in order to rebuild the early Calcium-Silicate-Hydrate (CSH) bridges and the lower amount of water available for further hydration. The number of pores and the pore distribution were also more pronounced in the case of lower time intervals. Increasing the inter-layer time interval or the printing speed both lowered the mechanical performance of the printed specimens. This study emphasizes that individual process parameters will affect not only the structural behavior of the material, but they will also affect the durability and consequently the resistance against aggressive chemical substances.

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.

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.

Evaluation of Adhesion Properties of Modified Asphalt Binders with Use of Binder Bond Strength Test

2017 ◽  
Vol 2632 (1) ◽  
pp. 88-98 ◽  
Author(s):  
Weidong Huang ◽  
Lu Zhou
Keyword(s):  
Bond Strength ◽  
Asphalt Binder ◽  
Gel Permeation Chromatography ◽  
Crumb Rubber ◽  
Asphalt Binders ◽  
Adhesion Properties ◽  
Rubber Powder ◽  
Positive Effects ◽  
Tracking Device ◽  
Styrene Butadiene

Moisture damage is a prominent problem of asphalt pavements. The bond strength between asphalt and aggregates is a crucial factor that influences the capability of asphalt to resist moisture-induced damage. In this study, a binder bond strength (BBS) test was conducted to evaluate the effects of various modifiers and additives of different amounts on bond strength between asphalt and aggregates. Furthermore, the influence of styrene–butadiene–styrene (SBS) on adhesion behavior of asphalt binder was investigated through a gel permeation chromatography (GPC) test. Finally, the results of the BBS test were compared with the findings obtained from a Hamburg wheel-tracking device (HWTD) test, which reflected the moisture sensitivity of mixtures under wet conditions. Results indicated that gilsonite, high-density polyethylene, and polyphosphoric acid improved the bond strength of the base asphalt; SBS had no positive effects on asphalt adhesion properties; and SBS at a low amount reduced the bond strength. Ethylene bis-stearamide wax, crumb rubber, terminal blend (TB) rubber powder, and compound modifier TB rubber powder plus SBS decreased the bond strength. The GPC test results showed that SBS possibly did not actively contribute to the formation of bond strength between asphalt and aggregates. Test data for BBS and HWTD tests under wet conditions confirmed that there was no discernible correlation between these two tests when adhesion properties of modified asphalts were evaluated. However, the results of the BBS test were in accordance with those of the HWTD test when the adhesion of asphalt with different amounts of the same modifier and the mixture resistance to water damage were evaluated.

An Experimental Determination of Optimum Processing Parameters for Al∕SiC Metal Matrix Composites Made Using Ultrasonic Consolidation

2007 ◽  
Vol 129 (4) ◽  
pp. 538-549 ◽  
Author(s):  
Y. Yang ◽  
G. D. Janaki Ram ◽  
B. E. Stucker
Keyword(s):  
Bond Strength ◽  
Metal Matrix Composites ◽  
Process Parameters ◽  
Metal Matrix ◽  
Oscillation Amplitude ◽  
Processing Parameters ◽  
Optimum Combination ◽  
Matrix Composites ◽  
Ultrasonic Consolidation ◽  
Push Out

Ultrasonic consolidation, an emerging additive manufacturing technology, is one of the most recent technologies considered for fabrication of metal matrix composites (MMCs). This study was performed to identify the optimum combination of processing parameters, including oscillation amplitude, welding speed, normal force, operating temperature, and fiber orientation, for manufacture of long-fiber-reinforced MMCs. A design of experiments approach (Taguchi L25 orthogonal array) was adopted to statistically determine the influences of individual process parameters. SiC fibers of 0.1mm diameter were successfully embedded into an Al 3003 metal matrix. Push-out testing was employed to evaluate the bond strength between the fiber and the matrix. Data from push-out tests and microstructural studies were analyzed and an optimum combination of parameters was achieved. The effects of process parameters on bond formation and fiber/matrix bond strength are discussed.

Screening of Different Encapsulated Polymer-Based Healing Agents for Chloride Exposed Self-Healing Concrete Using Chloride Migration Tests

2018 ◽  
Vol 761 ◽  
pp. 152-158 ◽  
Author(s):  
Philip van den Heede ◽  
Bjorn van Belleghem ◽  
Maria Adelaide Araújo ◽  
João Feiteira ◽  
Nele de Belie
Keyword(s):  
Service Life ◽  
High Viscosity ◽  
Cementitious Materials ◽  
Self Healing ◽  
Polymer Precursor ◽  
Marine Environments ◽  
Steel Reinforced Concrete ◽  
Low Viscosity ◽  
Chloride Migration ◽  
The One

The service life of steel reinforced concrete in aggressive marine environments could be increased substantially by embedding a self-healing mechanism that ensures autonomous healing of cracks upon their occurrence. Previous proof-of-concept experiments have shown that the incorporation of encapsulated polymer-based healing agents (HAs) counts as a very appropriate way to achieve this goal. Over the years, several polymer-precursor-capsule systems have been developed in that perspective at our laboratory. Cementitious materials containing either commercial or in-house developed encapsulated HAs have been subjected to preliminary feasibility tests (water absorption, permeability tests, etc.). However, these experiments did not yet allow for a fast and straightforward assessment of the self-healing efficiency (SHE) in relation to the expected durability and service life performance of the material. This approach would have many advantages when having to select the most suitable polymer-precursor-capsule system for a particular concrete application. In this paper, a modified chloride migration test based on the one prescribed in NT Build 492 has been proposed to support the development of self-healing concrete for marine environments. Four polymer-based HAs have been screened that way, i.e. an in-house developed high-viscosity polyurethane (PU) precursor, a commercial low-viscosity PU precursor, the same commercial PU precursor with addition of accelerator and benzoyl peroxide (BPO), and an in-house developed 2-component acrylate-endcapped precursor + cross-linker. For now, a highly repeatable SHE value of 100% could only be obtained for the second option.

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