3D printed concrete (3DPC) technology brings remarkable benefits to construction industry stakeholders. It offers design flexibility, construction automation, and precision while promoting waste reduction, material efficiency, and cost savings. By meeting the growing demand for sustainable practices, 3DPC enhances the lifecycle performance of concrete structures. This technical session aims to shed light on the recent innovations and applications of sustainable 3DPC, including, but not limited to, the innovations in use of low-carbon binders, geopolymers, and recycled and waste materials as additives, the exploration of low-binder solutions and life-cycle cost and environment impact analyses, and the application of advanced analytical tools, such as machine learning, in concrete mix design and performance prediction. It is to engage industry leaders, researchers, and practitioners in advancing 3DCP technology and to promote innovative materials, efficient processes, and resilient structures.
Learning Objectives:
Optimizing Rheological Performance of Low Carbon 3D Printable Cementitious Mixtures through Targeted Superabsorbent Polymer Incorporation
Presented By: Narayanan Neithalath
Affiliation: Arizona State University
Description: Low carbon cementitious systems for 3D printing are prone to multiple shrinkage phenomena including plastic, autogenous shrinkage and drying shrinkage, with autogenous shrinkage being particularly critical at low water to binder ratios. In this context, the use of superabsorbent polymers as internal curing agents presents a promising approach to mitigate shrinkage by serving as water reservoirs that gradually release moisture during hydration. This mechanism not only helps to reduce shrinkage but also modifies the fresh properties of the mixtures by increasing yield stress and viscosity, potentially enhancing printability. The present study focuses on the rheological behaviour of low carbon 3D printable cementitious mixtures modified with a range of superabsorbent polymers. The investigation examines variations in superabsorbent polymer chemistry, dosage levels and particle size distributions, with superabsorbent polymers classified into fine (less than 75 microns), medium (75 to 300 microns) and coarse (greater than 300 microns) fractions spanning a full gradation from 45 to 800 microns. The static and dynamic yield stresses, plastic viscosity and thixotropic properties were assessed to evaluate the overall flow behavior and structural build-up of the mixtures. Overall, the study provides valuable insights for optimizing mix designs in sustainable 3D printing by effectively controlling water retention and mitigating shrinkage, particularly plastic and autogenous shrinkage, through the targeted incorporation of superabsorbent polymers.
Optimizing 3D-Printed Concrete: A Sustainable Approach Using CPM and LCA
Presented By: Claudiane Ouellet-Plamondon
Affiliation: ETS Montreal, Universite Du Quebec
Description: Developing sustainable concrete formulations for 3D printing remains a crucial challenge in minimizing the environmental footprint of the construction sector. This study presents an optimized Limestone Calcined Clay Cement-based concrete specifically designed for two-component 3D printing. The Compressive Packing Model (CPM) was utilized to explore mix design possibilities through ternary diagrams, providing a structured representation of optimal proportions. To enhance sustainability, CPM was integrated with Life Cycle Assessment (LCA) to identify mixtures with the lowest carbon footprint while preserving both mechanical and rheological performance. By incorporating LCA into the optimization process, a mix achieving a compressive strength of 60 MPa was identified, balancing environmental and economic factors. A total of 20 different formulations were analyzed, significantly reducing the need for extensive experimental trials. Furthermore, rheological properties were refined by optimizing the superplasticizer dosage to ensure compatibility with extrusion-based 3D printing. The findings illustrate that combining CPM with LCA enables a comprehensive multi-criterion optimization approach, simultaneously addressing mechanical performance, workability, and sustainability. This strategy facilitates the adaptation of concrete formulations to locally available resources and eco-friendly alternatives, making it applicable to a broad range of sustainable construction initiatives. Ultimately, the proposed methodology streamlines the development of low-carbon concrete for 3D printing and provides an efficient framework for material selection and optimization in digital construction technologies.
Additive Construction of Low Embodied Carbon Concrete: Geopolymer Concrete
Presented By: Islam Mantawy
Affiliation: Rowan University
Description: Additive construction offers significant advantages over traditional methods, including precise material deposition, reduced waste, enhanced design flexibility for complex geometries, and accelerated construction timelines. However, conventional concrete production poses substantial environmental challenges, primarily due to the high energy consumption and greenhouse gas emissions associated with Portland cement. To mitigate these issues, this study investigates using geopolymer concrete – a sustainable, cement-free material made from industrial by-products activated by alkali activators – for additive construction. The research focuses on three key areas: (1) the development of customized geopolymer concrete mixtures tailored for additive construction, (2) the establishment of a reliable 3D printing process for constructing structures, and (3) the demonstration of the printability and structural integrity of 3D printed geopolymer elements. The results demonstrate that the developed mixtures enable the successful printing of intricate structures, such as circular paths, slopes, and varying cross-sections, validating their potential for additive construction. Additionally, findings indicate that (1) increasing slag content in the binder enhances compressive strength, (2) precise temperature control of the alkaline activator is crucial for optimizing setting time and printability, and (3) incorporating an idle period before printing facilitates the transition from a flowable mixture to a printable consistency. This research highlights the viability of geopolymer concrete as a sustainable alternative for additive construction, addressing environmental concerns while maintaining the structural and functional requirements of complex 3D printed structures.
Impact of 3D Printing Process Parameters on the Print Quality and Mechanical Properties of Geopolymers
Presented By: Oguzhan Sahin
Affiliation: Civil Engineering, Ankara University
Description: This study aimed to examine the impact of various operational and production parameters on the properties of 3D-printed geopolymer specimens. To achieve this, a printable geopolymer mixture was developed and evaluated for its extrudability and buildability using empirical tests (flowability and buildability assessments) and printing trials conducted at different printing speeds (ranging from 5 mm/s to 50 mm/s). Following these preliminary assessments, prismatic specimens were printed using four distinct path designs—regular, grid, angular, and criss-crossed. The mechanical properties of the printed specimens were then analysed based on their loading direction through compressive and flexural strength tests. The extrudability evaluation revealed that no cracks, voids, or defects were observed in the printed structures, even at high printing speeds. Additionally, the geopolymer mortar mixture demonstrated excellent buildability, as the printed structures maintained their intended shape without any discontinuities or defects. The buildability test results indicated a direct correlation between printing speed and deformation, with higher speeds leading to greater deformations. Regardless of the printing path design, specimens subjected to lateral loading exhibited higher compressive and flexural strength than those loaded perpendicularly. Among the different printing configurations, the criss-cross pattern achieved the highest compressive strength, followed by angular, grid, and regular designs. Similarly, the criss-cross configuration also yielded the greatest flexural strength, with the regular, angular, and grid patterns exhibiting progressively lower values. Overall, the findings highlight the anisotropic nature of 3D-printed structures. Moreover, the study suggests that optimizing production parameters—such as printing speed and path design—can significantly enhance the mechanical performance of 3D-printed geopolymer structures.
Exploring Low-Binder Solutions in Two-Stage 3D Concrete Printing for Reduced Carbon Footprint
Presented By: Onur Ozturk
Affiliation: Cornell University
Description: 3D concrete printing (3DCP) has often faced criticism regarding its sustainability due to the high cementitious material requirements needed for printability, which contribute to significant carbon emissions. A promising solution is the two-stage (2K) 3DCP system, where a flowable mixture is combined with an accelerator at the nozzle to provide the necessary structural build-up for the extruded material. This approach has the potential to reduce binder content, as the build-up is primarily facilitated by the accelerator, rather than relying heavily on the fine materials commonly used in one-stage systems. In our research, we explored the potential of the 2K system for reducing binder content while still achieving the necessary structural build-up which was assessed through green strength and buildability tests. We systematically reduced the binder content in the mixture while carefully optimizing the composition of non-reactive materials and adjusting the amount of accelerator injected at the nozzle. By analyzing the performance of the printed samples, we identified the limits of binder reduction within the 2K system without compromising structural stability. The results show that it is possible to significantly reduce binder content in 3DCP by the utilization of 2K system while maintaining adequate buildability and green strength, underscoring the potential of this approach to advance low-carbon concrete technologies. This research provides valuable insights into the optimization of 3D printing materials and contributes to the development of more sustainable, environmentally friendly construction practices.
Ultra-low Dosages of Novel Graphene Types Enhance the Rheological, Buildability, and Mechanical Properties of 3D Printed Binders
Presented By: Sahil Surehali
Affiliation: Arizona State University
Description: Incorporating graphene as a high-performance additive in concrete offers significant advantages; however, challenges related to cost, production scalability, and dispersion efficiency hinder its widespread adoption. This study examines the influence of ultra-low dosages (=0.02% by binder mass) of two novel graphene variants—fractal graphene (FG) and reactive graphene (RG)—manufactured through a cost-efficient, eco-friendly, and scalable detonation-based process, on the rheological and mechanical characteristics of 3D-printable concrete. FG and RG contribute to notable improvements in dynamic and static yield stresses and viscoelastic properties, with RG-modified mixtures displaying enhanced effects due to functionalized surface groups. The evolution of static yield stress (ts) and storage modulus (G’) provides insights into structural build-up mechanisms enabled by graphene particles, which are crucial for extrusion and shape retention. Experimental buildability tests on hollow cylindrical specimens indicate that the ultra-low graphene dosages more than double the maximum achievable build heights. Finally, the effects of ultra-low dosages of FG and RG on the hardened properties, specifically on compressive and flexural strength, are described to elucidate the improvements in mechanical properties due to graphene nanoparticles. Overall, FG and RG enable improved rheological properties and buildability, allowing for reduced cement content while maintaining or improving mechanical performance. Additionally, the cost-effective and environmentally friendly detonation synthesis process used for FG and RG significantly lowers the material's global warming potential (GWP) and energy demand. Therefore, FG and RG present a potential to develop high-performance 3D printable cement-based mixtures while meeting the rheological and printability requirements and enhancing structural integrity and material efficiency.
3D-Printed Concrete Acoustic Metamaterials for Low-Frequency Traffic Noise Mitigation
Presented By: David Cubillos
Affiliation:
Description: Traffic noise mitigation in the low- to mid-frequency range remains challenging, as conventional concrete barriers show limited effectiveness. This research investigates the development of 3D-printed concrete acoustic metamaterials designed to attenuate roadway noise through geometry-driven resonance. A honeycomb-type lattice integrating arrays of Helmholtz-type resonators was designed based on analytical models relating cavity volume, neck geometry, and impedance behavior to absorption performance. Numerical and experimental results demonstrated that the printed prototype increased sound absorption by more than twofold compared to the baseline condition, with coefficients exceeding 0.9 in the 770 Hz–1 kHz range and maintaining high performance up to 10 kHz. The prototypes were fabricated using a custom 3D-printable mortar optimized for rheological stability and geometric accuracy. These results confirm the feasibility of integrating resonant acoustic functionality directly into cementitious structures, demonstrating potential for scalable, sustainable, and frequency-selective noise barriers for transportation infrastructure.