{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,25]],"date-time":"2026-04-25T13:16:25Z","timestamp":1777122985312,"version":"3.51.4"},"reference-count":61,"publisher":"MDPI AG","issue":"14","license":[{"start":{"date-parts":[[2025,7,21]],"date-time":"2025-07-21T00:00:00Z","timestamp":1753056000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100003524","name":"Ministry of Business, Innovation &amp; Employment (MBIE) of New Zealand","doi-asserted-by":"publisher","award":["UOCX2204"],"award-info":[{"award-number":["UOCX2204"]}],"id":[{"id":"10.13039\/501100003524","id-type":"DOI","asserted-by":"publisher"}]},{"name":"University of Canterbury, Doctoral Scholarship from the Department of Civil and Environmental Engineering","award":["UOCX2204"],"award-info":[{"award-number":["UOCX2204"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Buildings"],"abstract":"<jats:p>Three-dimensional (3D) concrete printing (3DCP) has gained significant attention over the last decade due to its many claimed benefits. The absence of effective real-time quality control mechanisms, however, can lead to inconsistencies in extrusion, compromising the integrity of 3D-printed structures. Although the importance of quality control in 3DCP is broadly acknowledged, research lacks systematic methods. This research investigates the feasibility of using ultrasonic pulse velocity (UPV) as a practical, in situ, real-time monitoring tool for 3DCP. Two different groups of binders were investigated: limestone calcined clay (LC3) and zeolite-based mixes in binary and ternary blends. Filaments of 200 mm were extruded every 5 min, and UPV, pocket hand vane, flow table, and viscometer tests were performed to measure pulse velocity, shear strength, relative deformation, yield stress, and plastic viscosity, respectively, in the fresh state. Once the filaments presented printing defects (e.g., filament tearing, filament width reduction), the tests were concluded, and the open time was recorded. Isothermal calorimetry tests were conducted to obtain the initial heat release and reactivity of the supplementary cementitious materials (SCMs). Results showed a strong correlation (R2 = 0.93) between UPV and initial heat release, indicating that early hydration (ettringite formation) influenced UPV and determined printability across different mixes. No correlation was observed between the other tests and hydration kinetics. UPV demonstrated potential as a real-time monitoring tool, provided the mix-specific pulse velocity is established beforehand. Further research is needed to evaluate UPV performance during active printing when there is an active flow through the printer.<\/jats:p>","DOI":"10.3390\/buildings15142566","type":"journal-article","created":{"date-parts":[[2025,7,21]],"date-time":"2025-07-21T08:47:14Z","timestamp":1753087634000},"page":"2566","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":2,"title":["Ultrasonic Pulse Velocity for Real-Time Filament Quality Monitoring in 3D Concrete Printing Construction"],"prefix":"10.3390","volume":"15","author":[{"ORCID":"https:\/\/orcid.org\/0009-0001-5755-8879","authenticated-orcid":false,"given":"Luis","family":"de la Flor Juncal","sequence":"first","affiliation":[{"name":"Department of Civil and Environmental Engineering, University of Canterbury, Christchurch 8041, New Zealand"}]},{"given":"Allan","family":"Scott","sequence":"additional","affiliation":[{"name":"Department of Civil and Environmental Engineering, University of Canterbury, Christchurch 8041, New Zealand"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-6724-3037","authenticated-orcid":false,"given":"Don","family":"Clucas","sequence":"additional","affiliation":[{"name":"Department of Mechanical Engineering, University of Canterbury, Christchurch 8041, New Zealand"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-1834-8879","authenticated-orcid":false,"given":"Giuseppe","family":"Loporcaro","sequence":"additional","affiliation":[{"name":"Department of Civil and Environmental Engineering, University of Canterbury, Christchurch 8041, New Zealand"}]}],"member":"1968","published-online":{"date-parts":[[2025,7,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"508","DOI":"10.1016\/j.istruc.2022.06.068","article-title":"A review of largescale 3DCP: Material characteristics, mix design, printing process, and reinforcement strategies","volume":"43","author":"Ahmed","year":"2022","journal-title":"Structures"},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"106774","DOI":"10.1016\/j.cemconres.2022.106774","article-title":"Technology readiness: A global snapshot of 3D concrete printing and the frontiers for development","volume":"156","author":"Ma","year":"2022","journal-title":"Cem. 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