Mechanical Anisotropy and Pore Evolution Mechanism of 3D Printed Concrete

doi:10.16552/j.cnki.issn1001-1625.2025.1282

Abstract

Abstract:

3D printed concrete （3DPC） faces challenges regarding anisotropy and interlayer weakness， which limit its structural applications. This study investigated the intrinsic correlations between buildability， mechanical behavior， and pore structure of 3DPC through macro-micro scale analysis. Firstly， a material system suitable for extrusion was designed. Furthermore， X-ray computed tomography （X-CT） and digital image correlation （DIC） were employed to quantitatively analyze pore characteristics and their influence on damage evolution. The results show that 3DPC has excellent thixotropy and buildability， and achieves 19 layers of continuous stacking without collapse in ultimate buildability tests. DIC analysis reveals significant anisotropy in crack evolution： X-direction loading causes cracks to propagate upwards and downwards from the edges， Y-direction loading shows bottom-up propagation， while Z-direction loading induces 45° shear failure along the interlayer interface. Microscopic analysis confirms that the complex irregular pores and interlayer interfaces within 3DPC are the sources of crack initiation. This study not only validates the printing performance of the material but also provides a basis for revealing the damage mechanism and achieving crack precise control in 3DPC.

Key words: 3D printed concrete, pore structure, buildability, compressive strength, anisotropy, crack

CLC Number:

TU528

MA Lianxia, LIU Chao, CHEN Wei, ZHU Wenxuan, ZHAO Weifei, YANG Qiuju. Mechanical Anisotropy and Pore Evolution Mechanism of 3D Printed Concrete[J]. BULLETIN OF THE CHINESE CERAMIC SOCIETY, 2026, 45(6): 1914-1923.

Figures/Tables 16

Table 1 Main chemical composition of OPC， FA and SF

Material	Mass fraction/%
Material	CaO	SiO₂	Al₂O₃	Fe₂O₃	SO₃	MgO	K₂O	Na₂O
OPC	63.9	20.6	4.8	3.7	2.4	1.4	0.6	0.4
SF	1.0	86.6	0.5	1.5	0.6	2.8	2.0	0.6
FA`	5.8	51.4	28.2	3.4	1.1	1.3	0.7	0.9

Table 2 Mix ratio for printable mixtures

Material	OPC	ESA	Sand	FA	SF	CE	PVA	SP
Mix ratio/（g·L^-1）	756.4	146.4	1 220.0	48.8	24.4	0.3	0.6	2.9

Fig.1 Schematic diagram of specimen printing， cutting and loading direction

Fig.2 Stacked form of 3DPC specimen

Fig.3 Fluidity test of mortar

Fig.4 Comparison of compressive strength of different specimens

Fig.5 Cast specimens loaded at 7 d of curing

Fig.6 Printed specimens loaded in X-direction at 7 d of curing

Fig.7 Printed specimens loaded in Y-direction at 7 d of curing

Fig.8 Printed specimens loaded in Z-direction at 7 d of curing

Fig.9 Comparison of splitting tensile strength for different specimens

Fig.10 Comparison of flexural strength for different specimens

Fig.11 Three-dimensional pore structure distribution of specimens

Fig.12 Slice images of different specimens

Fig.13 Porosity distribution of different specimens at 1 d of curing （Z-direction）

Fig.14 Porosity distribution of different specimens at 28 d of curing （Z-direction）

References 25

[1]	KHAN M S， SANCHEZ F， ZHOU H Y. 3-D printing of concrete： beyond horizons［J］. Cement and Concrete Research， 2020， 133： 106070. DOI URL
[2]	MENNA C， MATA-FALCÓN J， BOS F P， et al. Opportunities and challenges for structural engineering of digitally fabricated concrete［J］. Cement and Concrete Research， 2020， 133： 106079. DOI URL
[3]	MOHAN M K， RAHUL A V， DE SCHUTTER G， et al. Extrusion-based concrete 3D printing from a material perspective： a state-of-the-art review［J］. Cement and Concrete Composites， 2021， 115： 103855. DOI URL
[4]	WOLFS R J M， BOS F P， SALET T A M. Hardened properties of 3D printed concrete： the influence of process parameters on interlayer adhesion［J］. Cement and Concrete Research， 2019， 119： 132-140. DOI URL
[5]	DING T， XIAO J Z， ZOU S， et al. Hardened properties of layered 3D printed concrete with recycled sand［J］. Cement and Concrete Composites， 2020， 113： 103724. DOI URL
[6]	夏锴伦，陈宇宁，刘超，等. 混凝土3D打印建造的低碳性研究进展［J］. 建筑结构学报， 2024， 45（3）： 15-33.
	XIA K L， CHEN Y N， LIU C， et al. Research progress on low carbon characters of 3D concrete printing based construction［J］. Journal of Building Structures， 2024， 45（3）： 15-33 （in Chinese）. DOI
[7]	KHOSHNEVIS B. Automated construction by contour crafting： related robotics and information technologies［J］. Automation in Construction， 2004， 13（1）： 5-19. DOI URL
[8]	娄梦帆，欧阳振宇. 增强聚合物纤维取向的3D打印壳核结构［C］//中国力学学会. 中国力学大会-2025摘要集（第三册）. 宁波大学， 2025： 261.
	LOU M F， OUYANG Z Y. 3D printed core-shell structure with enhanced polymer fiber orientation［C］// Chinese Society of Theoretical and Applied Mechanics. Abstracts of the Chinese Congress of Theoretical and Applied Mechanics-2025 （volume 3. Ningbo University， 2025： 261 （in Chinese）.
[9]	RAHUL A V， SANTHANAM M. Evaluating the printability of concretes containing lightweight coarse aggregates［J］. Cement and Concrete Composites， 2020， 109： 103570. DOI URL
[10]	张立卿，郭绵珍，李洪艳，等. 3D打印混凝土的流变性能及其影响因素研究综述［J］. 复合材料学报， 2024， 41（11）： 5754-5782.
	ZHANG L Q， GUO M Z， LI H Y， et al. A review of rheological properties and influencing factors of 3D printed concrete［J］. Acta Materiae Compositae Sinica， 2024， 41（11）： 5754-5782 （in Chinese）.
[11]	芮遨宇，王里，马国伟. 层间水膜对3D打印混凝土界面性能的影响［J］. 硅酸盐通报， 2023， 42（7）： 2281-2289.
	RUI A Y， WANG L， MA G W. Effect of interlayer water film on interfacial characteristics of 3D printed concrete［J］. Bulletin of the Chinese Ceramic Society， 2023， 42（7）： 2281-2289 （in Chinese）.
[12]	MECHTCHERINE V， BUSWELL R， KLOFT H， et al. Integrating reinforcement in digital fabrication with concrete： a review and classification framework［J］. Cement and Concrete Composites， 2021， 119： 103964. DOI URL
[13]	WOLFS R J M， BOS F P， SALET T A M. Triaxial compression testing on early age concrete for numerical analysis of 3D concrete printing［J］. Cement and Concrete Composites， 2019， 104： 103344. DOI URL
[14]	CHOUGAN M， HAMIDREZA GHAFFAR S， JAHANZAT M， et al. The influence of nano-additives in strengthening mechanical performance of 3D printed multi-binder geopolymer composites［J］. Construction and Building Materials， 2020， 250： 118928. DOI URL
[15]	KETEL S， FALZONE G， WANG B， et al. A printability index for linking slurry rheology to the geometrical attributes of 3D-printed components［J］. Cement and Concrete Composites， 2019， 101： 32-43. DOI URL
[16]	ZHANG C， HOU Z Y， CHEN C， et al. Design of 3D printable concrete based on the relationship between flowability of cement paste and optimum aggregate content［J］. Cement and Concrete Composites， 2019， 104： 10340
[17]	张荣飞. 3D打印混凝土力学性能及破坏机理研究［D］. 西安：西安建筑科技大学， 2022.
	ZHANG R F. Research on mechanical properties and failure mechanism of 3D printed concrete［D］. Xi’an： Xi’an University of Architecture and Technology， 2022 （in Chinese）.
[18]	MA G W， LI Z J， WANG L， et al. Mechanical anisotropy of aligned fiber reinforced composite for extrusion-based 3D printing［J］. Construction and Building Materials， 2019， 202： 770-783. DOI URL
[19]	RAHUL A V， SANTHANAM M， MEENA H， et al. Mechanical characterization of 3D printable concrete［J］. Construction and Building Materials， 2019， 227： 116710. DOI URL
[20]	ARUNOTHAYAN A R， NEMATOLLAHI B， RANADE R， et al. Fiber orientation effects on ultra-high performance concrete formed by 3D printing［J］. Cement and Concrete Research， 2021， 143： 106384. DOI URL
[21]	谢晓颖. 3D打印水泥砂浆微结构表征及其性能调控［D］. 南京：南京理工大学， 2023.
	XIE X Y. Microstructural characterization and performance regulation of 3D printed cement mortar［D］. Naning： Nanjing University of Science and Technology， 2023 （in Chinese）.
[22]	中国建筑材料联合会. 水泥砂浆流动度试验方法：［S］. 北京：中国标准出版社， 2005.
	China Building Materials Federation. Test method for fluidity of cement mortar：［S］. Beijing： Standards Press of China， 2005 （in Chinese）.
[23]	中华人民共和国住房和城乡建设部. 混凝土物理力学性能试验方法标准：［S］. 北京：中国建筑工业出版社， 2019.
	Ministry of Housing and Urban-Rural Development of the People’s Republic of China. Standard for test methods of physical and mechanical properties of concrete：［S］. Beijing： China Architecture & Building Press， 2019 （in Chinese）.
[24]	朱超，李欣，刘超，等. 3D打印再生混凝土孔隙缺陷构型与受力特性［J］. 建筑材料学报， 2025， 28（8）： 725-732.
	ZHU C， LI X， LIU C， et al. Pore defect configuration and mechanical characteristics of 3D printed recycled concrete［J］. Journal of Building Materials， 2025， 28（8）： 725-732 （in Chinese）.
[25]	YU S W， DU H J， SANJAYAN J. Aggregate-bed 3D concrete printing with cement paste binder［J］. Cement and Concrete Research， 2020， 136： 106169. DOI URL