Concrete-based additive construction (3DCP) leads the construction AM material stack, with cementitious extrusion capable of building 36-hour deployable shelters and pedestrian bridges longer than 100 m, while metal laser powder bed fusion (L-PBF) and polymer fused filament fabrication (FFF) remain bounded by part size, equipment envelope, and per-kilogram cost [S1][S3].
Material selection in this segment is not the same exercise as in automotive or aerospace series production: a process engineer is balancing rheology window, layer-bond strength, and long-term durability against a code environment that has not yet absorbed the technology as a default, and only 33 peer-reviewed MMAM-construction articles cleared a five-year Scopus/Web of Science filter as of the 2025 Ghasemi review [S1].
Cementitious Mixes: Rheology Is the Spec
In 3DCP, the print head is essentially a rheology pump, not a concrete truck: the same mix must flow through a 20-40 mm nozzle, hold shape under self-weight, and bond to the previous layer before its own set kinetics overtake the build rate [S2].
NIST's program description (2025) states that hydration kinetics, rheology, and nanoscale C-S-H formation all feed back into the macroscopic build rate, compressive strength, and inter-layer bond, which is why they treat the 3DCP process as a dynamic system rather than a static concrete pour [S2]. The same source flags inter-layer interfaces and web-to-perimeter connections as the primary crack-propagation paths in current reinforced 3DCP walls, which behave structurally closer to reinforced CMU masonry than to cast-in-place concrete [S2]. For a spec writer, that means the lever is not 28-day cylinder strength alone; it is open time, yield stress, thixotropy, and aggregate grading, each of which has to be qualified against the specific gantry or robotic arm being deployed.
Polymer Filaments and Metal Powders: Where They Fit, Where They Don't
FFF polymers (PLA, PETG, ABS, and engineering grades such as PC and PA-CF) are specified for formwork, mock-ups, jigs, and small architectural nodes, not for primary load-bearing structure, because layer adhesion, moisture uptake, and UV aging dominate long-term performance and are not yet codified for building enclosure or structural duty [S1][S3].
Metal L-PBF (typically 316L, 17-4 PH, maraging 300, Ti-6Al-4V, and AlSi10Mg) is used for custom connectors, facade anchors, and topology-optimized nodes, where Equispheres (2024-05) frames the material decision as a three-way trade between alloy selection, powder design (size distribution, morphology, flow), and process design (laser power, spot size, hatch, scan strategy) [S5]. A complementary 2026 spec-first walkthrough of metal powder selection for general fabrication maps the same selection logic onto construction-adjacent fabrication shops, where powder lot consistency and MQ/PQ data carry more weight than nominal alloy chemistry [S5][S6]. The hard constraint is build envelope: most construction-scale gantries operate in the 10-30 m range on at least one axis, and metal L-PBF chambers are typically limited to a few hundred millimetres on every axis, so metal AM in construction is a node-and-connector play, not a wall-and-slab play [S3][S6].
Regolith Geopolymers and Lunar/Off-Planet Concrete
Regolith-based geopolymers are positioned as a fourth material family, with the 2025 Heliyon scoping review explicitly listing them among the structural materials enabled by construction AM, and the same paper noting that AM reduces material waste and unlocks geometries that conventional formwork cannot achieve [S3].
For terrestrial construction, the practical question is binder availability and curing conditions: alkali-activated geopolymers and sulfoaluminate systems are being qualified for low-carbon and rapid-build scenarios, with mix design driven by locally sourced fines rather than by a single global reference mix [S3][S7]. A closer look at how construction AM overlaps with industrial 3D printing more broadly is given in this AM-material spec-first overview, which is a useful cross-check when justifying an AM bill of material to a project reviewer who only knows cast-in-place concrete [S3].
Selection Criteria: A Side-by-Side Map
Choosing among cementitious, polymer, metal, and geopolymer families is a four-criteria decision: build rate (kg/h or m²/h), part size, structural duty, and code acceptance, and a practical comparison looks like this: [S5]
Cementitious extrusion: high build rate, large envelope (10-30 m gantries are common), primary structural duty, but limited code coverage and weather-window sensitivity during placement [S2][S3]. Polymer FFF: low build rate, small-to-medium envelope, non-structural or temporary duty, and mature material standards inherited from the broader plastics industry [S1][S3]. Metal L-PBF: very low build rate per kg, small envelope, structural node duty, and the strongest MQ/PQ dataset of the four, but at the highest per-kilogram cost and the longest qualification cycle [S5]. Regolith-based geopolymers: experimental build rate, envelope set by the printer rather than the material, and essentially no building code at present, which confines them to research, defense, and space-agency pilots [S3][S7].
For process engineers the rule of thumb is: if the part is wall, slab, or column, specify a 3DCP mix and a qualified gantry; if the part is a connector, anchor, or topology-optimized node, specify a powder designed for the chosen L-PBF machine and request a documented MQ/PQ package; if the part is formwork, mock-up, or site jigs, polymer FFF is fine and should be selected for dimensional stability and UV/aging data rather than raw tensile strength [S1][S5][S6].
Limits, Failure Modes, and What's Still Missing
The Ghasemi 2025 review is explicit that the construction sector lags behind other AM industries, and it names the gap precisely: material interface challenges, environmental durability concerns, and the absence of design tools specific to building-scale components, alongside the need for standardized protocols covering Equipment Design, Process Control, Design Integration, Digital Tools, and Materials Research [S1].
On the failure-mode side, NIST highlights that the 3DCP process-machine-material coupling changes the failure path: layer interfaces, web-to-perimeter bonds, and the dependence of structural response on machine settings and material formulation are the open items blocking performance-based standards, which is why most current 3DCP practice borrows reinforced-masonry logic rather than reinforced-concrete logic [S2]. The Heliyon 2025 review adds that regulatory, safety, and quality challenges still cap construction AM, and the technology should complement rather than replace conventional methods in the near term [S3]. On the equipment side, the underlying gantry, pump, and print-head hardware that drives material placement is best understood through the construction machinery and equipment category reference, which sets the baseline for the pumps, robotic arms, and end-effectors that any mix design eventually has to survive [S3][S8].
Tooling, Formwork, and Site Adjacencies
Polymer and metal AM are also quietly reshaping the construction site itself, not just the structure, because 3D-printed formwork, custom rebar spacers, and topology-optimized connection hardware can be produced on or near the project [S3][S6].
For these applications, the spec-first logic is closer to general industrial AM than to architectural 3DCP: pick the alloy or polymer for the duty, pick the powder or filament design for the machine, and qualify the process with a documented MQ/PQ package; this is the same workflow a 2026 additive manufacturing material spec map for automotive series and tooling lays out, and the construction-site variants inherit the discipline even if the volumes are lower [S5]. For the printing and post-processing equipment itself, the construction tools category reference covers the hand-held and small-format hardware that prints jigs and fixtures on a site trailer, which is where most early construction-AM budgets actually land [S6][S8].
Where To Go Next
Track NIST's 3DCP measurement-science deliverables, the next Ghasemi/MMAM review cycle expected in 2026-2027, and any ACIL or ASTM E60 committee output on performance-based 3DCP standards; these are the three signals most likely to move construction AM from pilot to default spec. [S2]
On the materials side, watch for published MQ/PQ datasets on 316L and 17-4 PH for facade-anchor duty, and for sulfoaluminate and alkali-activated binder data tied to a specific gantry model, since the binder-printer pair is the unit a code-writer will actually cite [S2][S3][S5].