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:
(1) To introduce the concept of 3DPC and its significance in the context of sustainable construction practices;
(2) To share information on the technical aspects of sustainable 3DPC, including its compositions, printing quality, performance characteristics, and AI-enhanced performance predictions;
(3) To facilitate knowledge of the environmental benefits of sustainable 3DPC, such as reduced carbon emissions, energy savings, and improved resource efficiency;
(4) To discuss challenges and opportunities associated with the widespread adoption of sustainable 3DPC.
Functionally Efficient Structures by 3D Concrete Printing
Presented By: Kolluru Subramaniam
Affiliation: Indian Institute of Technology Hyderabad
Description: In construction, 3D concrete printing (3DCP) is emerging as a technology that has the potential to create a significant impact on the state of practice and overcome several limitations of conventional construction processes. 3DCP focuses on delivery systems that build a structure using layer deposition. 3DCP technology is, however, still in a nascent stage in construction-related applications. Techniques for printing free-standing structures are not sufficiently developed for large-scale applications. In this paper, the concept of form-specific structural system optimization that broadly follows ‘material-follows-force’ will be used to arrive at a shape that reduces weight while minimizing the requirement of conventional reinforcement. This concept of form optimization is demonstrated with the design of two structures: (a) a bridge that is off-site printed; and (b) an on-site printed protective structure against blast and ballistic threat.
The structural system of the bridge was developed following the concept of a tied arch. The tied arch, which combines the tension ties with compression struts, is used to develop a force transfer system that minimizes the reinforcement requirement. The form of the printed structure was developed by replacing the 2D stress field of continuous structure with a truss mesh of nodes and 1-D element connections representing the new reduced-weight lattice design as shown in Figure 1(a). The printed structural system was developed following a form optimization process involving iterative analysis and evaluation, as illustrated in Figure 1 (b) for a pedestrian bridge of 8 m span. The evolution of the structural system of the bridge is optimized for the use of material while ensuring stiffness.
The protective structure was designed with a structural system for out-of-plane loading. The surface of the structure was form-optimized for enhanced blast and ballistic performance. The structural form with integrated reinforcement consisted of laye
AI-driven Design of Sustainable 3D Printing Binders: Enhancing the use of Indigenous Materials
Presented By: Kamal Khayat
Affiliation: Missouri S&T
Description: The shift toward sustainable 3D printing binders requires reducing cement usage while maintaining print quality and mechanical performance. This study explores both commercially available and indigenous supplementary cementitious materials and fiber reinforcements as partial cement replacements. Fresh, hardened, and printing properties were systematically measured to establish printability criteria. An ensemble machine learning framework was developed to predict fresh and hardened properties, which were then applied as key indicators to evaluate the printability of each binder. The framework further enables the prediction of printing performance for mixtures deemed printable. To promote broader adoption, the developed machine learning model has been deployed as an online tool. Overall, this study demonstrates how AI-driven modeling can accelerate the screening and optimization of sustainable 3D printing binders.
Harnessing Concrete 3D Printing for Building Surface Cooling and Urban Heat Island Mitigation
Presented By: Hongyu Zhou
Affiliation: University of Tennessee
Description: Recent advances in large-scale concrete 3D printing and digital construction have significantly expanded the design possibilities for building envelopes, unlocking opportunities for multi-functional systems that reduce energy use and enhance thermal performance. This presentation introduces a 3D-printed vertical concrete green wall system (3D-VtGW), demonstrating how modular, prefabricated wall elements can serve both as the primary building enclosure and as an integrated green wall for surface cooling. A prototype commercial building in Nanjing, China was used to showcase how these multifunctional walls—via plant shading, evapotranspiration, and soil’s thermal storage—reduce exterior wall temperatures and overall through-wall heat transfer. This substantially improves occupant thermal comfort and contributes to the mitigation of urban heat island effects. Energy simulations based on local climatic conditions indicate notable reductions in energy consumption with the 3D-VtGW system. The findings emphasize the transformative potential of digital fabrication to integrate architecture, sustainability, and landscape design, ultimately enabling more efficient, climate-responsive buildings
Real-time Vibrorheological Control Strategies for 3D Printable Cement Mortar
Presented By: Jae Hong Kim
Affiliation: KAIST
Description: This presentation introduces a comprehensive vibrorheological control strategy for 3D printable cement-based materials, addressing key challenges in construction automation through innovative additive manufacturing techniques. Our research demonstrates how strategic application and elimination of vibration can effectively control the thixotropic behavior of cement-based materials throughout the printing process. By quantifying this relationship in energy density terms, we establish that vibration intensity directly correlates with both material flowability during extrusion and accelerated thixotropic recovery upon vibration cessation. The experimental framework examines how vibration affects cement-based materials in two critical phases: during application to enhance workability and after elimination to accelerate shape stability. Through rheological analysis and printing experiments, we demonstrate that materials can transition effectively from high flowability states necessary for extrusion to rapidly increasing yield stress when vibration is removed. This approach successfully addresses critical technical challenges including weak interlayer bonding, reinforcement integration, and shape stability maintenance. Printing tests validate that materials subjected to controlled vibration parameters demonstrated improved surface quality and reinforcement integration while requiring significantly reduced waiting times to achieve shape stability. This unified vibrorheological control methodology represents a significant advancement in optimizing additive construction processes and expanding the practical applications of 3D concrete printing technology.
AI-Powered Process Optimization for 3D-Printed Ultra-High-Performance Concrete Incorporating Agricultural Waste-Derived Pozzolans
Presented By: Yen-Fang Su
Affiliation: Louisiana State University
Description: Ultra-high performance concrete (UHPC) is a highly promising material for construction 3D
printing because of its superior mechanical performance and durability. Nevertheless, the high cement content has severe environmental issues, including high CO2 emissions and resource depletion. This study explores the possibility of using sugarcane bagasse ash (SCBA) as a supplementary cementitious material to enhance the sustainability of UHPC in the context of 3D printing technology. SCBA is an agricultural waste-derived pozzolan of sugarcane-based biofuel production with high amorphous silica content and pozzolanic activity. Therefore, SCBA can be a sustainable alternative to cement due to its amorphous silica and pozzolanic reactions, which can contribute to strength development. Its tilization not only improves concrete performance but also attains a circular economy via the recycling of industrial wastes. In addition, its fine particle size and pozzolanic nature can improve the printability of UHPC by adjusting rheological properties and improving the flow consistency during extrusion, ensuring smooth and stable layer deposition. Nevertheless, due to the highly variable nature of agricultural waste-derived materials, process optimization—including SCBA processing, UHPC mixing, and 3D printing—must be carefully designed. Thus, this research aims to leverage machine learning techniques to optimize the application of SCBA in UHPC and investigate its e ffects on fresh and hardened properties. The SCBA, sourced from different sugarcane farms, was meticulously characterized to establish the dataset. Trial mixes were then developed, and their designs were iterated using a sequential design methodology. The printability of the UHPC was evaluated based on key parameters such as rheological properties, setting time, extrudability, and buildability, while the mechanical performance of the printable UHPC was assessed through its hardened strength properties. The compatibility of SC
Sustainable 3D Printing with Bio-based Concrete
Presented By: Magdalena Rajczakowska
Affiliation: Lulea University of Technology
Description: This presentation discusses a preliminary study on the use of multiscale plant-based fibers in 3D concrete printing, focusing on their potential reinforcing effects and internal curing properties. The research explores how incorporating micronized hemp, millimeter-sized hemp particles, and plant fibers affects the properties of printed concrete. Heat of hydration measurements, TGA, and SEM were applied to quantify cement binder interactions with raw and NaOH-treated fibers. Compressive strength, rheology, and printability were evaluated.
Results show that treated hemp fines below 50 µm improve the composite's strength and rheology, whereas coarser particles weaken it. NaOH pre-treatment is necessary to prevent hydration retardation. Lignocellulosic fibers reduce density and offer crack control. Longer 6 mm fibers bridge macro-cracks, while sub-mm fibers control micro-cracking and shrinkage. Ongoing research will further investigate these mechanisms to support greener 3DCP with fossil-free reinforcement.
Sustainable 3DPC: Fact or Uncomfortable Fiction?
Presented By: Sean Monkman
Affiliation: Six Down Consulting LLC
Description: The perception that 3D printable concrete (3DPC) is inherently unsustainable is largely shaped by existing literature. A systematic review of over 1100 published 3DPC mix designs reveals that most formulations rely on high cement contents and exhibit GHG emissions significantly exceeding those of conventional ready-mixed concrete. However, low-carbon examples do exist, demonstrating that more sustainable approaches are possible. Insights into binder blends, aggregate proportions, and particle size distribution suggest best practices that can enhance 3DPC’s sustainability, necessitating a shift in research priorities. Mix designs with 1000 kg of cement and 1000 kg of sand should be unceremoniously retired.
Microstructural Investigation of the Effect of Freeze–Thaw Cycles on Bond Strength of 3D-Printed Concrete
Presented By: Seyed Moein Mousavi Takami
Affiliation: Clemson University
Description: The durability of 3D-printed concrete (3DPC) under freezing and thawing conditions remains one of the critical challenges for its long-term structural performance in cold climates. Unlike conventionally cast concrete, 3DPC exhibits distinct anisotropic properties due to its layer-by-layer deposition, leading to potential weaknesses at interlayer interfaces. Unlike conventionally cast concrete, 3DPC exhibits distinct anisotropic properties due to its layer-by-layer deposition, at the interlayer interfaces. This study investigates the degradation of interlayer bond strength in 3D-printed concrete subjected to repeated freeze–thaw (F–T) cycles and correlates the macroscopic strength loss with microstructural alterations. Two-layer and multilayer specimens were printed using cementitious mixtures with optimized rheology. Mechanical testing was conducted to evaluate the interlayer bond strength using the splitting tensile test at different exposure stages. Complementary microstructural analyses-including scanning electron microscopy (SEM), energy-dispersive X-ray spectroscopy (EDS), and X-ray computed tomography (XCT)-were conducted to characterize changes in pore structure, microcracking, and hydration products across the layer interface. The results from mass loss, dynamic modulus reduction, and interlayer bond strength tests before and after F–T exposure were correlated with the observed microstructural evolution.