{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2025,12,16]],"date-time":"2025-12-16T05:21:20Z","timestamp":1765862480745,"version":"3.48.0"},"reference-count":20,"publisher":"MDPI AG","issue":"24","license":[{"start":{"date-parts":[[2025,12,14]],"date-time":"2025-12-14T00:00:00Z","timestamp":1765670400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001659","name":"Deutsche Forschungsgemeinschaft","doi-asserted-by":"crossref","award":["414265976"],"award-info":[{"award-number":["414265976"]}],"id":[{"id":"10.13039\/501100001659","id-type":"DOI","asserted-by":"crossref"}]},{"name":"the Publication Fund of Technische Universit\u00e4t Braunschweig"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Buildings"],"abstract":"<jats:p>This study addresses the fabrication challenges associated with producing diverse geometries for concrete dry connections, particularly regarding cost, time, and geometric limitations. The research investigates methods for fabricating precise, rebar-free dry connections in concrete, focusing on stamping and green-state computer numerical control (CNC) milling. These methods are evaluated using metrics such as dimensional accuracy, tool abrasion, and energy consumption. In the stamping process, a design of experiments (DOE) approach varied water content, concrete age, stamping load, and operational factors (vibration and formwork) across cone, truncated cone, truncated pyramid, and pyramid geometries. An optimal age range of 90 to 105 min, within a broader operational window of 90 to 120 min, was identified. Geometry-specific exceptions, such as approximately 68 min for the truncated cone and 130 min for the pyramid, were attributed to interactions between shape and age rather than deviations from general guidance. Within the tested parameters, water fraction primarily influenced lateral geometric error (diameter or width), while age most significantly affected vertical error. For green-state milling, both extrusion- and shotcrete-printed stock were machined at 90 min, 1 day, and 1 week. From 90 min to 1 week, the total milling energy increased on average by about 35%, and at one week end-face (head) passes caused substantially higher tool wear, with mean circumference losses of about 3.2 mm for head engagement and about 1.0 mm for side passes. Tool abrasion and energy demand increased with curing time, and extrusion required marginally more energy at equivalent ages. Milling was conducted in two engagement modes: side (flank) and end-face (head), which were evaluated separately. End-face engagement resulted in substantially greater tool abrasion than side passes, providing a clear explanation for tolerance drift in final joint geometries. Additionally, soil-based forming, which involves imprinting the stamp into soft, oil-treated fine sand to create a reversible mold, produced high-fidelity replicas with clean release for intricate patterns. This approach offers a practical alternative where friction and demolding constraints limit the effectiveness of direct stamping.<\/jats:p>","DOI":"10.3390\/buildings15244521","type":"journal-article","created":{"date-parts":[[2025,12,15]],"date-time":"2025-12-15T15:15:08Z","timestamp":1765811708000},"page":"4521","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Fabrication of Dry Connection Through Stamping and Milling of Green-State Concrete"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0000-0003-1259-6174","authenticated-orcid":false,"given":"Abtin","family":"Baghdadi","sequence":"first","affiliation":[{"name":"Institute of Structural Design, Technical University of Braunschweig, Pockelsstrasse 4, 38106 Braunschweig, Germany"}]},{"given":"Kian","family":"Khanipour Raad","sequence":"additional","affiliation":[{"name":"Institute of Structural Design, Technical University of Braunschweig, Pockelsstrasse 4, 38106 Braunschweig, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-8473-7218","authenticated-orcid":false,"given":"Robin","family":"D\u00f6rrie","sequence":"additional","affiliation":[{"name":"Institute of Structural Design, Technical University of Braunschweig, Pockelsstrasse 4, 38106 Braunschweig, Germany"}]},{"ORCID":"https:\/\/orcid.org\/0000-0003-4891-869X","authenticated-orcid":false,"given":"Harald","family":"Kloft","sequence":"additional","affiliation":[{"name":"Institute of Structural Design, Technical University of Braunschweig, Pockelsstrasse 4, 38106 Braunschweig, Germany"}]}],"member":"1968","published-online":{"date-parts":[[2025,12,14]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"110456","DOI":"10.1016\/j.engstruct.2020.110456","article-title":"Experimental and numerical assessment of new precast concrete connections under bending loads","volume":"212","author":"Baghdadi","year":"2020","journal-title":"Eng. Struct."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"110004","DOI":"10.1016\/j.istruc.2025.110004","article-title":"Bolted steel plates for rigidly connecting decks to beams in precast concrete flooring systems","volume":"81","author":"Baghdadi","year":"2025","journal-title":"Structures"},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"115605","DOI":"10.1016\/j.engstruct.2023.115605","article-title":"Experimental and numerical assessments of new concrete dry connections concerning potentials of robotic CNC manufacturing technique","volume":"280","author":"Baghdadi","year":"2023","journal-title":"Eng. Struct."},{"key":"ref_4","doi-asserted-by":"crossref","unstructured":"Baghdadi, A., Heristchian, M., Ledderose, L., and Kloft, H. (2023). Experimental and numerical assessments of new concrete dry connections concerning potentials of the robotic subtractive manufacturing technique. Buildings, 13.","DOI":"10.3390\/buildings13010210"},{"key":"ref_5","doi-asserted-by":"crossref","unstructured":"Baghdadi, A., Meshkini, A., and Kloft, H. (2021, January 16\u201318). Inspiration of interlocking wooden puzzles for precast concrete construction. Proceedings of the International Fib Symposium on the Conceptual Design of Structures, Attisholz Areal, Switzerland.","DOI":"10.35789\/fib.PROC.0055.2021.CDSymp.P066"},{"key":"ref_6","doi-asserted-by":"crossref","unstructured":"Lanwer, J.P., Weigel, H., Baghdadi, A., Empelmann, M., and Kloft, H. (2022). Joining Principles in AMC\u2014Part 1: Design and Preparation of dry connections. Appl. Sci., 12.","DOI":"10.3390\/app12094138"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"D\u00f6rrie, R., David, M., Freund, N., Lowke, D., Dr\u00f6der, K., and Kloft, H. (2024, January 4\u20136). Surface Processing of Shotcrete 3D Printed Concrete Elements Using a Rotating Trowel Disc\u2013Influence of Timing on Resulting Surface Quality. Proceedings of the RILEM International Conference on Concrete and Digital Fabrication, Munich, Germany. Available online: https:\/\/link.springer.com\/chapter\/10.1007\/978-3-031-70031-6_46.","DOI":"10.1007\/978-3-031-70031-6_46"},{"key":"ref_8","doi-asserted-by":"crossref","unstructured":"Liu, W.J., Niu, X.J., Yang, N., Tan, Y.S., Qiao, Y., Liu, C.F., Wu, K., Li, Q.B., and Hu, Y. (2021). Prediction model of concrete initial setting time based on stepwise regression analysis. Materials, 14.","DOI":"10.3390\/ma14123201"},{"key":"ref_9","doi-asserted-by":"crossref","unstructured":"Lee, J.C. (2023). Evaluation of setting times of concrete using the electro-mechanical impedance sensing technique. Materials, 16.","DOI":"10.3390\/ma16165618"},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"60","DOI":"10.1016\/j.cemconcomp.2013.04.008","article-title":"Effect of curing methods on strength and durability of concrete under hot weather conditions","volume":"41","author":"Ibrahim","year":"2013","journal-title":"Cem. Concr. Compos."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"143","DOI":"10.1617\/s11527-024-02408-9","article-title":"Assessing the setting behavior of ultra-high performance concrete","volume":"57","author":"Saladi","year":"2024","journal-title":"Mater. Struct."},{"key":"ref_12","first-page":"401","article-title":"A Comparative Study on the Effect of Curing on the Strength of Concrete","volume":"2","author":"Goel","year":"2013","journal-title":"Int. J. Eng. Adv. Technol. (IJEAT)"},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"52","DOI":"10.1016\/j.istruc.2022.01.089","article-title":"A review of formwork systems for modern concrete construction","volume":"38","author":"Li","year":"2022","journal-title":"Structures"},{"key":"ref_14","unstructured":"Arnold, R. (2003). Working with Concrete, Taunton Press."},{"key":"ref_15","first-page":"e03848","article-title":"A review on early-age cracking of concrete: Causes and control","volume":"21","author":"Qu","year":"2024","journal-title":"Case Stud. Constr. Mater."},{"key":"ref_16","doi-asserted-by":"crossref","unstructured":"Gamil, Y., Nilimaa, J., Emborg, M., and Cwirzen, A. (2021). Lateral formwork pressure for self-compacting concrete\u2014A review of prediction models and monitoring technologies. Materials, 14.","DOI":"10.3390\/ma14164767"},{"key":"ref_17","doi-asserted-by":"crossref","first-page":"1099","DOI":"10.1617\/s11527-014-0274-y","article-title":"Form pressure generated by fresh concrete: A review about practice in formwork design","volume":"47","author":"Proske","year":"2014","journal-title":"Mater. Struct."},{"key":"ref_18","doi-asserted-by":"crossref","first-page":"840","DOI":"10.1002\/best.201600043","article-title":"Shear strength of thin-walled micro-reinforced concrete members","volume":"111","author":"Busse","year":"2016","journal-title":"Beton Stahlbetonbau"},{"key":"ref_19","doi-asserted-by":"crossref","first-page":"115050","DOI":"10.1016\/j.matdes.2025.115050","article-title":"Investigation on process guidelines and geometric capabilities for robust shotcrete 3D printing","volume":"260","author":"Lachmayer","year":"2025","journal-title":"Mater. Des."},{"key":"ref_20","unstructured":"(2009). Testing Fresh Concrete\u2014Part 5: Flow Table Test (Standard No. DIN EN 12350-5)."}],"container-title":["Buildings"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/2075-5309\/15\/24\/4521\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2025,12,16]],"date-time":"2025-12-16T05:19:20Z","timestamp":1765862360000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/2075-5309\/15\/24\/4521"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2025,12,14]]},"references-count":20,"journal-issue":{"issue":"24","published-online":{"date-parts":[[2025,12]]}},"alternative-id":["buildings15244521"],"URL":"https:\/\/doi.org\/10.3390\/buildings15244521","relation":{},"ISSN":["2075-5309"],"issn-type":[{"type":"electronic","value":"2075-5309"}],"subject":[],"published":{"date-parts":[[2025,12,14]]}}}