{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,8]],"date-time":"2026-04-08T07:58:23Z","timestamp":1775635103915,"version":"3.50.1"},"reference-count":60,"publisher":"MDPI AG","issue":"7","license":[{"start":{"date-parts":[[2026,4,7]],"date-time":"2026-04-07T00:00:00Z","timestamp":1775520000000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Qinglan Project in Jiangsu Province of China"},{"name":"Directive Project of Taizhou Science and Technology Support Program","award":["TS202432"],"award-info":[{"award-number":["TS202432"]}]},{"name":"Jiangsu Provincial Department of Education\u2019s \u201cQinglan Project\u201d for Colleges and Universities \u201cRoad and Bridge Engineering Technology Teaching Team\u201d","award":["2024-14"],"award-info":[{"award-number":["2024-14"]}]},{"award":["2024-14"],"award-info":[{"award-number":["2024-14"]}],"id":[{"id":"https:\/\/ror.org\/059md9404","id-type":"ROR","asserted-by":"publisher"}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>To enhance the utilization rate and mechanical performance of recycled sand (RS) in extrusion-based 3D printing, this study investigates the influence of varying incorporation ratios of RS across two particle size fractions: 0.075\u20131.18 mm (RS01) and 1.18\u20132.36 mm (RS12). The RS utilization rate was determined via the material balance method, while microstructural mechanisms were analyzed using scanning electron microscopy and Vickers microhardness testing. The results indicate that: a combination of 75% RS01 and 25% RS12 achieves the maximum RS utilization rate of 84.3%. At an RS12\/RS01 ratio of 1:3, the printed specimens exhibit the smallest tilt angles in bidirectional buildability tests, measuring 7.6\u00b0 and 7.2\u00b0, with corresponding tan \u03b8 values of 0.066 and 0.063. Compared to mortar with 100% RS01, this optimized mixture yields average increases of 36.5% in compressive strength, 40.7% in flexural strength, and 6.8% in interlayer splitting strength. Analysis of variance indicates that different particle size combinations have a significant effect on the mechanical properties. Microhardness analysis reveals that the combination of 75% RS01 and 25% RS12 achieves a minimum interfacial transition zone width of 46 \u00b5m. Utilizing larger-particle-size RS in 3D printing effectively enhances its utilization rate while maintaining satisfactory printability and mechanical properties.<\/jats:p>","DOI":"10.3390\/ma19071478","type":"journal-article","created":{"date-parts":[[2026,4,8]],"date-time":"2026-04-08T07:25:12Z","timestamp":1775633112000},"page":"1478","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Optimizing the Utilization Rate and Performance of 3D-Printed Mortar with Dual-Size Recycled Sand"],"prefix":"10.3390","volume":"19","author":[{"given":"Jie","family":"Huang","sequence":"first","affiliation":[{"name":"School of Urban and Rural Construction, Taizhou Polytechnic College, Taizhou 225300, China"}]},{"given":"Xinjie","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Urban Construction, Changzhou University, Changzhou 213164, China"}]},{"given":"Quanbin","family":"Shi","sequence":"additional","affiliation":[{"name":"School of Urban and Rural Construction, Taizhou Polytechnic College, Taizhou 225300, China"}]},{"given":"Pu","family":"Yuan","sequence":"additional","affiliation":[{"name":"School of Urban Construction, Changzhou University, Changzhou 213164, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5327-0026","authenticated-orcid":false,"given":"Minqi","family":"Hua","sequence":"additional","affiliation":[{"name":"School of Civil Engineering & Architecture, Wuhan University of Technology, Wuhan 430070, China"}]}],"member":"1968","published-online":{"date-parts":[[2026,4,7]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"101032","DOI":"10.1016\/j.cogsc.2025.101032","article-title":"Current trends and challenges in construction and demolition waste recycling","volume":"53","author":"Bonifazi","year":"2025","journal-title":"Curr. 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