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 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.

Curing of slag concretes at low temperatures: effect on selected durability properties

MRS Advances ◽  
2020 ◽  
Vol 5 (25) ◽  
pp. 1267-1275
Author(s):  
Mike Otieno ◽  
Riccardo Opeka
Keyword(s):  
Oxygen Permeability ◽  
Gas Permeability ◽  
Curing Temperature ◽  
Durability Properties ◽  
Chloride Resistance ◽  
Blastfurnace Slag ◽  
Water Sorptivity ◽  
Chloride Conductivity ◽  
Strength And Durability ◽  
Durability Performance

AbstractThe influence of low curing temperatures (5, 10 and 15 ± 2 °C) on the strength and durability properties of ground granulated blastfurnace slag (GGBS) and ground granulated Corex slag (GGCS) concretes was studied. A standard curing temperature of 23 ± 2 °C) was also used for comparative purposes. Test specimens were cast using 100% CEM I 52.5N (PC), and three PC/Slag (GGBS or GGCS) replacement ratios of 50/50, 65/35 and 80/20, and a w/b ratio of 0.40. The specimens were cured for 28 days by submersion in water at the respective curing temperatures and then tested for durability. Durability was assessed using oxygen permeability, water sorptivity and chloride conductivity tests. The results showed that durability of the concretes decreased as the curing temperature decreased – gas permeability and water sorptivity increased while chloride resistance decreased. It was also observed that at a given curing temperature, the slag blended concretes showed superior durability performance than the plain PC concretes.

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 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 Effect of Influence of Metakaolin and Shredded Plastic Waste on Strength and Durability Properties of M20 Grade Concrete

2019 ◽  
Vol 8 (2) ◽  
pp. 4170-4175
Keyword(s):  
Natural Resources ◽  
Industrial Waste ◽  
Coarse Aggregate ◽  
Environmental Problems ◽  
Plastic Waste ◽  
Strength Parameters ◽  
Durability Properties ◽  
Natural Aggregates ◽  
Strength And Durability ◽  
Durability Performance

The production of cement liberates the equal amount of CO2 into the environment. This will results in various social and environmental problems. There is a need in determining the new cement materials from waste or industrial waste. Second, the extraction of natural aggregates from natural resources poses other environmental problems. So in this article, the experimental programme is conducted to determine the strength and durability performance of cement partially replaced with Metakaolin (MK) (0%, 2.5%, 5%, 7.5% and 10%) and coarse aggregate substituted by shredded plastic waste (SPW) at 0.5% by weight. The main objective of this article was limited to analyzing the strength parameters along with the durability parameters.

scholarly journals Durability Of Advanced Cement-Based Materials Used As Repairs For Deteriorated Concrete

2021 ◽  
Author(s):  
Keikhosrow Tahmureszadeh
Keyword(s):  
Bond Strength ◽  
High Performance Concrete ◽  
Construction Material ◽  
Advanced Technology ◽  
Repair System ◽  
Freeze Thaw ◽  
Thaw Cycle ◽  
Cement Based Materials ◽  
Strength And Durability ◽  
Durability Performance

With advanced technology, the production of strong construction material becomes more feasible. However, use of such materials as repairs on top of existing concrete is challenging, since repair system relies not only on the quality of repair but also on the interaction and compatibility of such material with the substrate. Studies regarding the durability of bond strength are limited. Therefore, the objective of this research is to compare the bond strength and durability performance of advanced cement-based materials including ultra-high performance concrete (UHPC), engineered cementitious composite with slag (ECC-Slag), specialized repair material with self-consolidating properties (SCC), and normal concrete (NC) under two common deterioration modes in Canada (freeze-thaw cycles with de-icing salt, and volumetric expansion of the substrate). The freeze-thaw cycle results show higher bond strength and durability performance for UHPC and NC, respectively. Under expanding deterioration, NC started with higher bond strength and UHPC revealed the best durability performance.

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 Fresh, Mechanical, and Durability Properties of Self-Compacting Mortar Incorporating Alumina Nanoparticles and Rice Husk Ash

Materials ◽  
2021 ◽  
Vol 14 (22) ◽  
pp. 6778
Author(s):  
Bahareh Mehdizadeh ◽  
Soheil Jahandari ◽  
Kirk Vessalas ◽  
Hania Miraki ◽  
Haleh Rasekh ◽  
...  
Keyword(s):  
Electrical Resistivity ◽  
Flexural Strength ◽  
Water Absorption ◽  
Rice Husk ◽  
Rice Husk Ash ◽  
Alumina Nanoparticles ◽  
Chloride Permeability ◽  
Cement Replacement ◽  
Durability Properties ◽  
Durability Performance

This paper presents a comprehensive evaluation on self-compacting (SC) mortars incorporating 0, 1, 3, and 5% alumina nanoparticles (NA) as well as 0% and 30% rice husk ash (RHA) used as Portland cement replacement. To evaluate the workability, mechanical, and durability performance of SC mortars incorporating NA and RHA, the fresh properties (slump flow diameter and V-funnel flow time), hardened properties (compressive strength, flexural strength, and ultrasonic pulse velocity), and durability properties (water absorption, rapid chloride permeability, and electrical resistivity) were determined. The results indicated that the addition of NA and RHA has negligible effect on the workability and water absorption rate of the SC mortars. However, significant compressive and flexural strength development was observed in the SC mortars treated with NA or the combination of NA and RHA. The introduction of RHA and NA also reduced the rapid chloride permeability and enhanced the electrical resistivity of the SC mortars significantly. It is concluded that the coexistence of 30% RHA and 3% NA as cement replacement in SC mortars can provide the best mechanical and durability performance.

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
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