Juxtaposing fresh material characterisation methods for buildability assessment of 3D printable cementitious mortars

Freek P. Bos; Jacques Kruger; Sandra S. Lucas; Gideon van Zijl

doi:10.1016/j.cemconcomp.2021.104024

Juxtaposing fresh material characterisation methods for buildability assessment of 3D printable cementitious mortars

Freek P. Bos (Corresponding author)
, Jacques Kruger
, Sandra S. Lucas
, Gideon van Zijl

Research output: Contribution to journal › Article › Academic › peer-review

79 Citations (Scopus)

203 Downloads (Pure)

Abstract

Both industry and academia are rapidly developing processes, materials, and projects to explore the potential of extrusion-layering additive manufacturing of cementitious materials, generally known as 3D concrete printing (3DCP). Because the lack of supportive formwork makes objects prone to failure during printing, a key aspect remains the so-called ‘buildability’, a qualitative descriptor to indicate the resistance against such failures. Obviously, the material characteristics of the applied print mortar are an important (although not sole) parameter to determine buildability. However, it is not yet clear which material properties are the most suitable, and how they should be determined experimentally. In literature, a range of approaches has been suggested, but comparative studies are very few in number and limited in scope. This paper presents a juxtaposition of fresh material characterisation methods by subjecting four different mortars to a range of tests related to buildability, including rotational rheometry, unconfined uniaxial compression tests, direct shear tests, and ultrasonic wave transmission tests. For reference, some hardened state properties were also determined, and a printing trial was performed on one mixture. Significant differences between the mixtures were found, including different development characteristics, even though three of the four mixtures were composed of different proportions of the
same 4 dry materials. Furthermore, it was shown that strength values from different experiments could only be correlated by assuming significant friction angles associated with Mohr-Coulomb failure behaviour. We propose this could be established relatively easily through a novel method, by combining rheometry-shear and uniaxial compression test results. The data seem to indicate this would be a valid approach. Normalized but physically different parameters, such as compressive strength and pulse velocity, could not be
consistently correlated. Their proportions are time and mixture-dependent, which adds significant complexity to quality control and the development of generalized methods to characterize and compare buildability of cementitious mortars.

Original language	English
Article number	104024
Number of pages	18
Journal	Cement & Concrete Composites
Volume	120
DOIs	https://doi.org/10.1016/j.cemconcomp.2021.104024
Publication status	Published - 1 Jul 2021

Funding

Overall, the pure shear strengths develop at a reasonably comparable pace, although noticeable differences occur, e.g. between t = 10 and 30 min. This may be associated with the differences in orientation of the shear planes in the three different tests, the scatter in measurement of the friction angle in DST as well as deviations from the pure stress states assumed in both the RR and UUCT, e.g. through non-homogenous shear distributions in the former or support confinement in the latter. Further experimental research will be required to definitely establish degree of correlation, but based on these results we preliminarily assume it to hold. Thus, friction angles have also been calculated for mixtures B, C, and D, and results listed in Table 7b. The authors would like to gratefully acknowledge the assistance of TU/e MSc students G. van Bakel, T. Gremmen, D. Muijres, and I. Vidimlić, who performed a considerable part of the experimental work presented in this paper. Furthermore, we appreciate the support of Chryso, Vliegasunie, and Saint Gobain Weber Beamix who supplied materials. The SU authors gratefully acknowledge the support of The Concrete Institute, as well as the Wilhelm Frank Trust.

Keywords

3D concrete printing
Buildability
Characterisation
Direct shear
Extrusion layering
Rheology
Rigidity
Strength
Ultrasonic
Unconfined uniaxial compression

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Bos et al. Juxtaposing fresh characterization methodsFinal published version, 3.23 MBLicence: CC BY

Cite this

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title = "Juxtaposing fresh material characterisation methods for buildability assessment of 3D printable cementitious mortars",

abstract = "Both industry and academia are rapidly developing processes, materials, and projects to explore the potential of extrusion-layering additive manufacturing of cementitious materials, generally known as 3D concrete printing (3DCP). Because the lack of supportive formwork makes objects prone to failure during printing, a key aspect remains the so-called {\textquoteleft}buildability{\textquoteright}, a qualitative descriptor to indicate the resistance against such failures. Obviously, the material characteristics of the applied print mortar are an important (although not sole) parameter to determine buildability. However, it is not yet clear which material properties are the most suitable, and how they should be determined experimentally. In literature, a range of approaches has been suggested, but comparative studies are very few in number and limited in scope. This paper presents a juxtaposition of fresh material characterisation methods by subjecting four different mortars to a range of tests related to buildability, including rotational rheometry, unconfined uniaxial compression tests, direct shear tests, and ultrasonic wave transmission tests. For reference, some hardened state properties were also determined, and a printing trial was performed on one mixture. Significant differences between the mixtures were found, including different development characteristics, even though three of the four mixtures were composed of different proportions of the same 4 dry materials. Furthermore, it was shown that strength values from different experiments could only be correlated by assuming significant friction angles associated with Mohr-Coulomb failure behaviour. We propose this could be established relatively easily through a novel method, by combining rheometry-shear and uniaxial compression test results. The data seem to indicate this would be a valid approach. Normalized but physically different parameters, such as compressive strength and pulse velocity, could not be consistently correlated. Their proportions are time and mixture-dependent, which adds significant complexity to quality control and the development of generalized methods to characterize and compare buildability of cementitious mortars. ",

keywords = "3D concrete printing, Buildability, Characterisation, Direct shear, Extrusion layering, Rheology, Rigidity, Strength, Ultrasonic, Unconfined uniaxial compression",

author = "Bos, \{Freek P.\} and Jacques Kruger and Lucas, \{Sandra S.\} and \{van Zijl\}, Gideon",

year = "2021",

month = jul,

day = "1",

doi = "10.1016/j.cemconcomp.2021.104024",

language = "English",

volume = "120",

journal = "Cement \& Concrete Composites",

issn = "0958-9465",

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TY - JOUR

T1 - Juxtaposing fresh material characterisation methods for buildability assessment of 3D printable cementitious mortars

AU - Bos, Freek P.

AU - Kruger, Jacques

AU - Lucas, Sandra S.

AU - van Zijl, Gideon

PY - 2021/7/1

Y1 - 2021/7/1

N2 - Both industry and academia are rapidly developing processes, materials, and projects to explore the potential of extrusion-layering additive manufacturing of cementitious materials, generally known as 3D concrete printing (3DCP). Because the lack of supportive formwork makes objects prone to failure during printing, a key aspect remains the so-called ‘buildability’, a qualitative descriptor to indicate the resistance against such failures. Obviously, the material characteristics of the applied print mortar are an important (although not sole) parameter to determine buildability. However, it is not yet clear which material properties are the most suitable, and how they should be determined experimentally. In literature, a range of approaches has been suggested, but comparative studies are very few in number and limited in scope. This paper presents a juxtaposition of fresh material characterisation methods by subjecting four different mortars to a range of tests related to buildability, including rotational rheometry, unconfined uniaxial compression tests, direct shear tests, and ultrasonic wave transmission tests. For reference, some hardened state properties were also determined, and a printing trial was performed on one mixture. Significant differences between the mixtures were found, including different development characteristics, even though three of the four mixtures were composed of different proportions of the same 4 dry materials. Furthermore, it was shown that strength values from different experiments could only be correlated by assuming significant friction angles associated with Mohr-Coulomb failure behaviour. We propose this could be established relatively easily through a novel method, by combining rheometry-shear and uniaxial compression test results. The data seem to indicate this would be a valid approach. Normalized but physically different parameters, such as compressive strength and pulse velocity, could not be consistently correlated. Their proportions are time and mixture-dependent, which adds significant complexity to quality control and the development of generalized methods to characterize and compare buildability of cementitious mortars.

AB - Both industry and academia are rapidly developing processes, materials, and projects to explore the potential of extrusion-layering additive manufacturing of cementitious materials, generally known as 3D concrete printing (3DCP). Because the lack of supportive formwork makes objects prone to failure during printing, a key aspect remains the so-called ‘buildability’, a qualitative descriptor to indicate the resistance against such failures. Obviously, the material characteristics of the applied print mortar are an important (although not sole) parameter to determine buildability. However, it is not yet clear which material properties are the most suitable, and how they should be determined experimentally. In literature, a range of approaches has been suggested, but comparative studies are very few in number and limited in scope. This paper presents a juxtaposition of fresh material characterisation methods by subjecting four different mortars to a range of tests related to buildability, including rotational rheometry, unconfined uniaxial compression tests, direct shear tests, and ultrasonic wave transmission tests. For reference, some hardened state properties were also determined, and a printing trial was performed on one mixture. Significant differences between the mixtures were found, including different development characteristics, even though three of the four mixtures were composed of different proportions of the same 4 dry materials. Furthermore, it was shown that strength values from different experiments could only be correlated by assuming significant friction angles associated with Mohr-Coulomb failure behaviour. We propose this could be established relatively easily through a novel method, by combining rheometry-shear and uniaxial compression test results. The data seem to indicate this would be a valid approach. Normalized but physically different parameters, such as compressive strength and pulse velocity, could not be consistently correlated. Their proportions are time and mixture-dependent, which adds significant complexity to quality control and the development of generalized methods to characterize and compare buildability of cementitious mortars.

KW - 3D concrete printing

KW - Buildability

KW - Characterisation

KW - Direct shear

KW - Extrusion layering

KW - Rheology

KW - Rigidity

KW - Strength

KW - Ultrasonic

KW - Unconfined uniaxial compression

UR - https://www.scopus.com/pages/publications/85104455822

U2 - 10.1016/j.cemconcomp.2021.104024

DO - 10.1016/j.cemconcomp.2021.104024

M3 - Article

SN - 0958-9465

VL - 120

JO - Cement & Concrete Composites

JF - Cement & Concrete Composites

M1 - 104024

ER -

Juxtaposing fresh material characterisation methods for buildability assessment of 3D printable cementitious mortars

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