The role of early age structural build-up in digital fabrication with concrete

Reiter, Lex; Wangler, Timothy; Roussel, Nicolas; Flatt, Robert J.

doi:10.1016/j.cemconres.2018.05.011

Cited by 324 publications

(125 citation statements)

References 40 publications

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“…3D concrete printing (3DCP), also referred to as digital fabrication or additive manufacturing of concrete, has been under development by both the academic research and construction industries in the past decade [1][2][3]. The unique advantages of 3DCP over conventional concrete construction may include saving labors and costs, eliminating formwork, increasing flexibility in architecture design, as well as reducing the construction time [3][4][5][6]. Until now, there are two main approaches in 3DCP: the extrusion-based method and the powder-based method [2,7].…”

Section: Introductionmentioning

confidence: 99%

Limestone and Calcined Clay-Based Sustainable Cementitious Materials for 3D Concrete Printing: A Fundamental Study of Extrudability and Early-Age Strength Development

Chen

Figueiredo

et al. 2019

Applied Sciences

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The goal of this study is to investigate the effects of different grades of calcined clay on the extrudability and early-age strength development under ambient conditions. Four mix designs were proposed. Three of them contained high, medium, and low grades of calcined clay, respectively, and one was the reference without calcined clay. In terms of extrudability, an extrusion test method based on the ram extruder was introduced to observe the quality of extruded material filaments, and to determine the extrusion pressure of tested materials at different ages. For evaluating the very early-age strength development, the penetration resistance test, the green strength test, and the ultrasonic pulse velocity test were applied. Furthermore, the mechanical properties of the developed mix designs were determined by the compressive strength test at 1, 7 and 28 days. Finally, the main finding of this study was that increasing the metakaolin content in calcined clay could significantly increase the extrusion pressures and green strength, shorten the initial setting time and enhance the compressive strength at 1, 7, and 28 days.

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Section: Introductionmentioning

confidence: 99%

Limestone and Calcined Clay-Based Sustainable Cementitious Materials for 3D Concrete Printing: A Fundamental Study of Extrudability and Early-Age Strength Development

Chen

Figueiredo

et al. 2019

Applied Sciences

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“…Literature authors have assumed that the rate of formation of Calcium silicate hydrate (CSH) crystal during the so-called "dormant" is constant because of the heat of hydration. Consequently, they conclude that, during this period, the evolution of the mechanical properties is linear then followed by an exponential part [57,58]. After 80 min, increases of resistance on order of 168%, 137% for M1, M2 while M3 remains relatively constant in terms of mechanical performance.…”

Section: Buildability Evaluationmentioning

confidence: 94%

Experimental Approach for Printability Assessment: Toward a Practical Decision-Making Framework of Printability for Cementitious Materials

et al. 2019

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The objective of this paper is to propose a pre-experimental framework of printability pre-assessment of cementitious materials. This study firstly presents a general review of additive manufacturing in construction and then examines the main characteristic of the material formulation and printability properties based on extrusion technique. This framework comes with experimental tests to determine a qualitative printability index of mixtures. It uses mix-designs reported in the literature to define interval ratio of mixture design to be investigated in this study. The focus was put on two criteria that influence the formulation namely flowability and buildability. Two practiced based tests, mini slump and cone penetrometer, were used to draw the flowability and buildability dimensionless index. The results were analyzed by introducing an optimal printability coefficient and examining their time evolution. An optimal time of printing was determined Toptimal. Finally, a 3D mortar printing system and its operational process are presented. Then, based on the measurement, the optimal mixture is identified and printed in a large-scale geometry.

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“…In addition to the inherent stability of the strand, the printed material also has to bear the load of the subsequent layers. To enable the printed layer to bear the load of the next layer without collapsing, a minimum yield stress is necessary [5,[17][18][19][20]. For this purpose, t min defines the point in time when a subsequent layer can be applied to the existing layer [20], see Figure 1.…”

Section: Introductionmentioning

confidence: 99%

The Effect of Accelerator Dosage on Fresh Concrete Properties and on Interlayer Strength in Shotcrete 3D Printing

2020

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Recently, the progress in 3D concrete printing has developed enormously. However, for the techniques available, there is still a severe lack of knowledge of the functional interaction of processing technology, concrete rheology and admixture usage. For shotcrete 3D printing technology, we present the effect of accelerator dosages (0%, 2%, 4% and 6%) on fresh concrete properties and on interlayer strength. Therefore, early yield stress development up to 90 min is measured with penetration resistance measurements. Deformation of layers under loading is investigated with digital image correlation and a mechanical testing machine. One point in time (10 min after deposition) is examined to quantify vertical buildability of elements depending on the accelerator dosage. Four different interlayer times (0, 2, 5 and 30 min), which occur for the production of small and large elements as well as due to delay during production, are investigated mechanically as well as quantitatively with computed tomography regarding the formation of cold joints. With increased accelerator dosage, an instantaneous increase in early age yield stress and yield stress evolution was observed. An increase in interlayer time leads to a reduced strength. This is mainly attributed to the observed reduced mechanical interlocking effect of the strands. Finally, a model to describe interlayer quality is presented. In the end, advantages as well as limitations of the findings are discussed.

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The role of early age structural build-up in digital fabrication with concrete

Cited by 324 publications

References 40 publications

Limestone and Calcined Clay-Based Sustainable Cementitious Materials for 3D Concrete Printing: A Fundamental Study of Extrudability and Early-Age Strength Development

Limestone and Calcined Clay-Based Sustainable Cementitious Materials for 3D Concrete Printing: A Fundamental Study of Extrudability and Early-Age Strength Development

Experimental Approach for Printability Assessment: Toward a Practical Decision-Making Framework of Printability for Cementitious Materials

The Effect of Accelerator Dosage on Fresh Concrete Properties and on Interlayer Strength in Shotcrete 3D Printing

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