Cold-Region Additively Constructed Concrete at Sustained −20°C

Abstract This study investigates the feasibility of additively constructed concrete (ACC) under sustained subfreezing conditions (−20°C), an environment that has been largely unaddressed in the existing literature. A gantry-based ACC system was developed within a temperature-controlled enclosure, alongside a cold-weather cementitious formulation (LC-CW) using conventional materials and chemical admixtures to promote early hydration. A brief early-age heating regimen was applied after an initial 6-h subfreezing period to counter the strength suppression observed under sustained −20°C curing, after which curing proceeded at −20°C without further thermal intervention. Fresh-state evaluation confirmed that LC-CW retained approximately 84% of its initial slump flow after 60 min while achieving sufficient early-age structural buildup for continuous layer stacking. The heating regimen increased the 1-day compressive strength to 34.6 MPa and enabled the material to reach the 3.5-MPa frost-protection threshold at approximately 12 h. Laboratory-cast specimens exceeded long-term strength targets, and field-extracted cores reached higher strengths (79.6 MPa at 28 days) owing to increased thermal mass. Interlayer bond strength averaged 2.3 MPa, with a substantial portion of specimens failing in the bulk material rather than at the interface, and no mass loss or surface deterioration occurred after 300 freeze–thaw cycles. Full-scale validation was completed by printing a 1.8-m-tall wall under continuous exposure at −20°C. These results demonstrate the feasibility of ACC using conventional construction materials in extreme cold environments, broadening its applicability for cold-region and remote construction.