{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,4,9]],"date-time":"2026-04-09T20:30:38Z","timestamp":1775766638300,"version":"3.50.1"},"reference-count":66,"publisher":"MDPI AG","issue":"3","license":[{"start":{"date-parts":[[2026,1,25]],"date-time":"2026-01-25T00:00:00Z","timestamp":1769299200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Hubei Provincial Key Laboratory of Construction and Management in Hydropower Engineering, Three Gorges University","award":["2023KSD018"],"award-info":[{"award-number":["2023KSD018"]}]},{"name":"Hubei International Science and Technology Cooperation Base of Fish Passage, China Three Gorges University"}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>Phosphogypsum (PG) is the main by-product of wet-process phosphoric acid production. Its annual global production reaches about 200 million tons, yet its utilization rate remains low. Consequently, long-term stockpiling of large PG volumes poses immense pressure to the ecological environment. To mitigate negative environmental impacts, the utilization of PG is imperative. Despite progress in PG utilization and 3D-printing technology, there is still a significant lack of understanding about the synergistic activation mechanisms in multi-solid-waste systems. In particular, the composition design, microstructure evolution, and structure\u2013property relationships of 3D-printed PG-based composites are not well-studied, which limits their high-value engineering applications. Three-dimensional-printed phosphogypsum concrete (3DPPGC) is proposed here, promoting PG resource utilization by leveraging the expanding applications of 3D-printed concrete (3DPC). However, the strength of 3DPPGC needs to be enhanced to meet engineering requirements. This study designed the mix proportion of 3DPPGC and fabricated the corresponding test specimens. The optimal Cement Replacement Ratio (CRR) was determined through experimental testing, and the mechanism behind the strength enhancement of the 3DPPGC was elucidated. The results indicated that the 3DPPGC\u2019s mechanical properties peaked at the 70% CRR. Compared with cast specimens, 3DPPGC exhibited a 1.52% increase in 28-day flexural strength in the y-direction, reaching 4.69 MPa. The early-age compressive strength, flexural strength, and later-age compressive strength of 3DPPGC were significantly enhanced when PG, blast-furnace slag (BS), fly ash (FA), and silica fume (SF) were used to partially replace cement. This study provides a theoretical and experimental basis for the large-scale, high-value application of PG in intelligent construction.<\/jats:p>","DOI":"10.3390\/ma19030482","type":"journal-article","created":{"date-parts":[[2026,1,26]],"date-time":"2026-01-26T12:41:16Z","timestamp":1769431276000},"page":"482","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":1,"title":["Strength Enhancement of 3D-Printed Phosphogypsum Concrete Based on Synergistic Activation of Multi-Solid Wastes"],"prefix":"10.3390","volume":"19","author":[{"given":"Junjie","family":"Li","sequence":"first","affiliation":[{"name":"College of Hydraulic and Environmental Engineering, China Three Gorges University, Yichang 443002, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6821-5751","authenticated-orcid":false,"given":"Yangbo","family":"Li","sequence":"additional","affiliation":[{"name":"College of Hydraulic and Environmental Engineering, China Three Gorges University, Yichang 443002, China"}]},{"given":"Xianqiang","family":"Ge","sequence":"additional","affiliation":[{"name":"POWERCHINA BEIJING Engineering Corporation Limited, Beijing 100024, China"}]},{"given":"Ke","family":"Li","sequence":"additional","affiliation":[{"name":"POWERCHINA BEIJING Engineering Corporation Limited, Beijing 100024, China"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-3496-7944","authenticated-orcid":false,"given":"Yahui","family":"Yang","sequence":"additional","affiliation":[{"name":"College of Hydraulic and Environmental Engineering, China Three Gorges University, Yichang 443002, China"}]},{"given":"Shuo","family":"Wang","sequence":"additional","affiliation":[{"name":"College of Hydraulic and Environmental Engineering, China Three Gorges University, Yichang 443002, China"}]}],"member":"1968","published-online":{"date-parts":[[2026,1,25]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"330","DOI":"10.1016\/j.jclepro.2017.04.002","article-title":"Potential benefits of digital fabrication for complex structures: Environmental assessment of a robotically fabricated concrete wall","volume":"154","author":"Hack","year":"2017","journal-title":"J. Clean. Prod."},{"key":"ref_2","doi-asserted-by":"crossref","first-page":"117075","DOI":"10.1016\/j.conbuildmat.2019.117075","article-title":"3D printing of curved concrete surfaces using Adaptable Membrane Formwork","volume":"232","author":"Lim","year":"2020","journal-title":"Constr. Build. Mater."},{"key":"ref_3","doi-asserted-by":"crossref","first-page":"125","DOI":"10.1016\/j.conbuildmat.2018.05.202","article-title":"3D-printed steel reinforcement for digital concrete construction\u2013Manufacture, mechanical properties and bond behaviour","volume":"179","author":"Mechtcherine","year":"2018","journal-title":"Constr. Build. Mater."},{"key":"ref_4","doi-asserted-by":"crossref","first-page":"475","DOI":"10.1007\/s11431-016-9077-7","article-title":"State-of-the-art of 3D printing technology of cementitious material\u2014An emerging technique for construction","volume":"61","author":"Ma","year":"2018","journal-title":"Sci. China Technol. Sci."},{"key":"ref_5","doi-asserted-by":"crossref","first-page":"102933","DOI":"10.1016\/j.autcon.2019.102933","article-title":"Large-scale digital concrete construction\u2013CONPrint3D concept for on-site, monolithic 3D-printing","volume":"107","author":"Mechtcherine","year":"2019","journal-title":"Autom. Constr."},{"key":"ref_6","doi-asserted-by":"crossref","first-page":"172","DOI":"10.1016\/j.compositesb.2018.02.012","article-title":"Additive manufacturing (3D printing): A review of materials, methods, applications and challenges","volume":"143","author":"Ngo","year":"2018","journal-title":"Compos. Part B"},{"key":"ref_7","doi-asserted-by":"crossref","unstructured":"Lyu, F., Zhao, D., Hou, X., Sun, L., and Zhang, Q. (2021). Overview of the development of 3D-printing concrete: A review. Appl. Sci., 11.","DOI":"10.3390\/app11219822"},{"key":"ref_8","first-page":"1769","article-title":"Research Progress and Application of 3D Printing Concrete","volume":"40","author":"Zhang","year":"2021","journal-title":"Bull. Chin. Ceram. Soc."},{"key":"ref_9","first-page":"639","article-title":"A Study on the removal of phosphorus and fluorine impurities from phosphogypsum","volume":"40","author":"Li","year":"2020","journal-title":"Acta Mineral. Sin."},{"key":"ref_10","doi-asserted-by":"crossref","first-page":"558","DOI":"10.1080\/00207233.2017.1330582","article-title":"Phosphogypsum: Potential uses and problems\u2014A review","volume":"74","author":"Saadaoui","year":"2017","journal-title":"Int. J. Environ. Stud."},{"key":"ref_11","doi-asserted-by":"crossref","first-page":"732","DOI":"10.1016\/j.jclepro.2017.08.049","article-title":"Phosphogypsum as a construction material","volume":"166","author":"Rashad","year":"2017","journal-title":"J. Clean. Prod."},{"key":"ref_12","first-page":"115","article-title":"Comprehensive utilization of phosphogypsum and research suggestions on key common technology innovation","volume":"40","author":"Gu","year":"2020","journal-title":"Conserv. Util. Miner. Resour."},{"key":"ref_13","doi-asserted-by":"crossref","first-page":"2150075","DOI":"10.1142\/S0218625X2150075X","article-title":"Comprehensive utilization of phosphogypsum: Adsorption of methylene blue and its application in bricks","volume":"28","author":"Gao","year":"2021","journal-title":"Surf. Rev. Lett."},{"key":"ref_14","doi-asserted-by":"crossref","first-page":"42","DOI":"10.1016\/j.scitotenv.2016.02.070","article-title":"Pollutant flows from a phosphogypsum disposal area to an estuarine environment: An insight from geochemical signatures","volume":"553","author":"Sarmiento","year":"2016","journal-title":"Sci. Total Environ."},{"key":"ref_15","doi-asserted-by":"crossref","unstructured":"Chernysh, Y., Yakhnenko, O., Chubur, V., and Roub\u00edk, H. (2021). Phosphogypsum recycling: A review of environmental issues, current trends, and prospects. Appl. Sci., 11.","DOI":"10.3390\/app11041575"},{"key":"ref_16","first-page":"4","article-title":"Production and discharge of phosphogypsum and research progress on its resource utilization","volume":"49","author":"Zhou","year":"2022","journal-title":"Yunnan Chem. Technol."},{"key":"ref_17","first-page":"1","article-title":"Analysis of comprehensive utilization and industrial development status of phosphogypsum in China in 2023","volume":"39","author":"Cui","year":"2024","journal-title":"Eco-Ind. Sci. Phosphorus Fluor. Eng."},{"key":"ref_18","first-page":"534","article-title":"Research progress on comprehensive utilization of phosphogypsum and its application in the field of building materials","volume":"43","author":"Zhou","year":"2024","journal-title":"Bull. Chin. Ceram. Soc."},{"key":"ref_19","first-page":"167","article-title":"Research progress on comprehensive utilization of phosphogypsum for materials: A review","volume":"37","author":"Zhang","year":"2023","journal-title":"Mater. Rep."},{"key":"ref_20","first-page":"102","article-title":"Study on preparation and modification of phosphogypsum-based architectural gypsum","volume":"55","author":"Guo","year":"2023","journal-title":"Inorg. Chem. Ind."},{"key":"ref_21","first-page":"801","article-title":"Experimental Investigation on Gypsum-Based Self-Leveling Building Putty Materials","volume":"12","author":"Wang","year":"2022","journal-title":"Mater. Sci."},{"key":"ref_22","unstructured":"Wang, Z., Xu, X., Su, L., and Gao, X. (2025). Preparation and properties of phosphogypsum based cement cementitious 3D printing materials. Concrete, 168\u2013172."},{"key":"ref_23","first-page":"1557","article-title":"Study Progress on Reinforcement Technology for 3D Printing Concrete","volume":"43","author":"Mao","year":"2024","journal-title":"Bull. Chin. Ceram. Soc."},{"key":"ref_24","doi-asserted-by":"crossref","first-page":"184","DOI":"10.12677\/HJCE.2019.82024","article-title":"Review on the Performance of Concrete in 3D Printing\u2014Fast-Setting and Early-Strength Concrete","volume":"8","author":"Zhang","year":"2019","journal-title":"Hans J. Civ. Eng."},{"key":"ref_25","doi-asserted-by":"crossref","first-page":"119271","DOI":"10.1016\/j.conbuildmat.2020.119271","article-title":"3D-printable lightweight foamed concrete and comparison with classical foamed concrete in terms of fresh state properties and mechanical strength","volume":"254","author":"Falliano","year":"2020","journal-title":"Constr. Build. Mater."},{"key":"ref_26","first-page":"67","article-title":"Investigation of the printability and mechanical properties of 3D printing UHPC","volume":"35","author":"Bai","year":"2021","journal-title":"Mater. Rep."},{"key":"ref_27","doi-asserted-by":"crossref","first-page":"104688","DOI":"10.1016\/j.cemconcomp.2022.104688","article-title":"Systematic approach for printability evaluation and mechanical property optimization of spray-based 3D printed mortar","volume":"133","author":"Liu","year":"2022","journal-title":"Cem. Concr. Compos."},{"key":"ref_28","doi-asserted-by":"crossref","first-page":"123938","DOI":"10.1016\/j.conbuildmat.2021.123938","article-title":"Stability of steel slag as fine aggregate and its application in 3D printing materials","volume":"299","author":"Dai","year":"2021","journal-title":"Constr. Build. Mater."},{"key":"ref_29","first-page":"97","article-title":"Research progress of cementitious materials and related properties for building 3D printing","volume":"12","author":"Xu","year":"2023","journal-title":"Mater. Rep."},{"key":"ref_30","first-page":"27","article-title":"Comprehensive utilization and impurity removal methods of phosphogypsum","volume":"38","author":"Yan","year":"2023","journal-title":"Phosphate Compd. Fertil."},{"key":"ref_31","first-page":"3248","article-title":"Effect of fluoride on structure and properties of gypsum-based cementitious materials","volume":"42","author":"Guo","year":"2023","journal-title":"Bull. Chin. Ceram. Soc."},{"key":"ref_32","doi-asserted-by":"crossref","unstructured":"Sinka, M., Vai\u010diukynien\u0117, D., Nizevi\u010dien\u0117, D., Sapata, A., Forn\u00e9s, I.V., Vaitkevi\u010dius, V., and \u0160erelis, E. (2024). Utilisation of By-Product Phosphogypsum Through Extrusion-Based 3D Printing. Materials, 17.","DOI":"10.3390\/ma17225570"},{"key":"ref_33","doi-asserted-by":"crossref","first-page":"132802","DOI":"10.1016\/j.conbuildmat.2023.132802","article-title":"Synergistic solidification\/stabilization mechanism of cadmium in phosphogypsum slag-based cementitious material","volume":"400","author":"Ren","year":"2023","journal-title":"Constr. Build. Mater."},{"key":"ref_34","first-page":"136","article-title":"Study on performance optimization and mechanism of phosphogypsumbased composite cementitious materials","volume":"54","author":"Zhang","year":"2022","journal-title":"Inorg. Chem. Ind."},{"key":"ref_35","doi-asserted-by":"crossref","unstructured":"Sahmenko, G., Puzule, L., Sapata, A., Slosbergs, P., Bumanis, G., Sinka, M., and Bajare, D. (2024). Gypsum\u2013cement\u2013Pozzolan composites for 3D printing: Properties and life cycle assessment. J. Compos. Sci., 8.","DOI":"10.3390\/jcs8060212"},{"key":"ref_36","doi-asserted-by":"crossref","unstructured":"Liu, X., Zhai, S., and Zhang, X. (2025). Research on the Effect of Sodium Aluminate on the Early Performance Enhancement and Mechanism of Phosphogypsum-Based Cementitious Materials. Materials, 18.","DOI":"10.3390\/ma18122707"},{"key":"ref_37","doi-asserted-by":"crossref","unstructured":"Tarhan, Y., and Atalay, B.J.P. (2025). Phosphogypsum and Borogypsum as Additives for Sustainable and High-Performance 3D-Printable Concrete. Polymers, 17.","DOI":"10.3390\/polym17182530"},{"key":"ref_38","doi-asserted-by":"crossref","first-page":"1802123","DOI":"10.1002\/adma.201802123","article-title":"Additive manufacturing and performance of architectured cement-based materials","volume":"30","author":"Moini","year":"2018","journal-title":"Adv. Mater."},{"key":"ref_39","first-page":"1545","article-title":"A Fundamental Study Progress on Reinforcement Enhancement of 3D Printed Concrete","volume":"43","author":"Xiao","year":"2024","journal-title":"Bull. Chin. Ceram. Soc."},{"key":"ref_40","doi-asserted-by":"crossref","first-page":"1296","DOI":"10.1016\/j.conbuildmat.2009.12.006","article-title":"Investigation on phosphogypsum\u2013steel slag\u2013granulated blast-furnace slag\u2013limestone cement","volume":"24","author":"Huang","year":"2010","journal-title":"Constr. Build. Mater."},{"key":"ref_41","unstructured":"(2012). Methods for Chemical Analysis of Gypsum (Standard No. GB\/T 5484-2012)."},{"key":"ref_42","doi-asserted-by":"crossref","first-page":"94","DOI":"10.1016\/j.conbuildmat.2017.02.072","article-title":"Effect of triethanolamine on cement hydration toward initial setting time","volume":"141","author":"Yaphary","year":"2017","journal-title":"Constr. Build. Mater."},{"key":"ref_43","first-page":"1113","article-title":"Effect of Fly Ash and Silica Fume Contents on Mechanical Properties of Alkali-Activated Slag-Based Concrete","volume":"59","author":"Xia","year":"2023","journal-title":"J. Southwest Jiaotong Univ."},{"key":"ref_44","unstructured":"(2009). Standard for Test Method of Basic Properties of Construction Mortar (Standard No. JGJ\/T 70-2009)."},{"key":"ref_45","unstructured":"(2005). Test Method for Fluidity of Cement Mortar (Standard No. GB\/T 2419-2005)."},{"key":"ref_46","doi-asserted-by":"crossref","unstructured":"Lafhaj, Z., Rabenantoandro, A.Z., El Moussaoui, S., Dakhli, Z., and Youssef, N. (2019). Experimental approach for printability assessment: Toward a practical decision-making framework of printability for cementitious materials. Buildings, 9.","DOI":"10.3390\/buildings9120245"},{"key":"ref_47","doi-asserted-by":"crossref","unstructured":"Bhattacherjee, S., and Santhanam, M. (2020). Enhancing buildability of 3D printable concrete by spraying of accelerating admixture on surface. Proceedings of the Second RILEM International Conference on Concrete and Digital Fabrication: Digital Concrete, Springer.","DOI":"10.1007\/978-3-030-49916-7_2"},{"key":"ref_48","doi-asserted-by":"crossref","first-page":"106868","DOI":"10.1016\/j.cemconres.2022.106868","article-title":"Hardened properties of 3D printed concrete with recycled coarse aggregate","volume":"159","author":"Liu","year":"2022","journal-title":"Cem. Concr. Res."},{"key":"ref_49","unstructured":"(2003). Standard for Test Method of Mechanical Properties on Ordinary Concrete (Standard No. GB\/T 50081-2002)."},{"key":"ref_50","doi-asserted-by":"crossref","first-page":"118759","DOI":"10.1016\/j.jclepro.2019.118759","article-title":"Effect of different gypsums on the workability and mechanical properties of red mud-slag based grouting materials","volume":"245","author":"Li","year":"2020","journal-title":"J. Clean. Prod."},{"key":"ref_51","doi-asserted-by":"crossref","first-page":"035506","DOI":"10.1088\/2053-1591\/ac5ef6","article-title":"Effect of the phosphogypsum calcination time on the compressive mechanical properties of phosphogypsum-based composite cementitious materials","volume":"9","author":"Zheng","year":"2022","journal-title":"Mater. Res. Express"},{"key":"ref_52","doi-asserted-by":"crossref","first-page":"125685","DOI":"10.1016\/j.conbuildmat.2021.125685","article-title":"Investigation on mechanical properties of excess-sulfate phosphogypsum slag cement: From experiments to molecular dynamics simulation","volume":"315","author":"Li","year":"2022","journal-title":"Constr. Build. Mater."},{"key":"ref_53","doi-asserted-by":"crossref","first-page":"342","DOI":"10.1007\/s11595-010-3342-7","article-title":"Effect of sodium hydroxide on the properties of phosphogypsum based cement","volume":"25","author":"Huang","year":"2010","journal-title":"J. Wuhan Univ. Technol. Mater. Sci. Ed."},{"key":"ref_54","unstructured":"Si, C. (2013). Basic Research on the Solidification of Bayer Process Red Mud. [Master\u2019s Thesis, Kunming University]. (In Chinese)."},{"key":"ref_55","first-page":"172","article-title":"Analysis of Bayer red mud activation mechanism and performance based on orthogonal experiment","volume":"16","author":"Li","year":"2022","journal-title":"Mater. Rep."},{"key":"ref_56","doi-asserted-by":"crossref","first-page":"747","DOI":"10.1016\/S0008-8846(00)00213-1","article-title":"Degree of hydration and gel\/space ratio of high-volume fly ash\/cement systems","volume":"30","author":"Lam","year":"2000","journal-title":"Cem. Concr. Res."},{"key":"ref_57","doi-asserted-by":"crossref","first-page":"457","DOI":"10.1016\/j.conbuildmat.2013.09.058","article-title":"Influence of lithium sulfate addition on the properties of Portland cement paste","volume":"50","author":"Deng","year":"2014","journal-title":"Constr. Build. Mater."},{"key":"ref_58","doi-asserted-by":"crossref","unstructured":"Lin, R.-S., Wang, X.-Y., Lee, H.-S., and Cho, H.-K. (2019). Hydration and microstructure of cement pastes with calcined Hwangtoh clay. Materials, 12.","DOI":"10.3390\/ma12030458"},{"key":"ref_59","doi-asserted-by":"crossref","first-page":"819","DOI":"10.1016\/j.cemconcomp.2012.04.001","article-title":"Improved geopolymerization of bottom ash by incorporating fly ash and using waste gypsum as additive","volume":"34","author":"Boonserm","year":"2012","journal-title":"Cem. Concr. Compos."},{"key":"ref_60","doi-asserted-by":"crossref","first-page":"123668","DOI":"10.1016\/j.conbuildmat.2021.123668","article-title":"Physico-mechanical and microstructural properties of sodium sulfate activated materials: A review","volume":"295","author":"Adesina","year":"2021","journal-title":"Constr. Build. Mater."},{"key":"ref_61","first-page":"782","article-title":"Solidification of Red Mud from Bayer Process Using Chemically Bonded Ceramics","volume":"33","author":"Luo","year":"2014","journal-title":"Bull. Chin. Ceram. Soc."},{"key":"ref_62","doi-asserted-by":"crossref","first-page":"118930","DOI":"10.1016\/j.conbuildmat.2020.118930","article-title":"Study on the inorganic synthesis from recycled cement and solid waste gypsum system: Application in grouting materials","volume":"251","author":"Lin","year":"2020","journal-title":"Constr. Build. Mater."},{"key":"ref_63","doi-asserted-by":"crossref","first-page":"1480","DOI":"10.1016\/j.conbuildmat.2006.07.010","article-title":"Study on lime\u2013fly ash\u2013phosphogypsum binder","volume":"21","author":"Shen","year":"2007","journal-title":"Constr. Build. Mater."},{"key":"ref_64","doi-asserted-by":"crossref","first-page":"9","DOI":"10.1016\/j.conbuildmat.2019.04.052","article-title":"Effect of modified phosphogypsum on the hydration properties of the phosphogypsum-based supersulfated cement","volume":"214","author":"Liu","year":"2019","journal-title":"Constr. Build. Mater."},{"key":"ref_65","doi-asserted-by":"crossref","first-page":"2803","DOI":"10.1520\/JTE20180702","article-title":"Effect of modified phosphogypsum on properties of cement mortar","volume":"48","author":"Gong","year":"2020","journal-title":"J. Test. Eval."},{"key":"ref_66","doi-asserted-by":"crossref","first-page":"227","DOI":"10.1016\/j.cemconcomp.2013.10.010","article-title":"Investigation of properties of fluorogypsum-slag composite binders\u2013hydration, strength and microstructure","volume":"45","author":"Garg","year":"2014","journal-title":"Cem. Concr. Compos."}],"container-title":["Materials"],"original-title":[],"language":"en","link":[{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/3\/482\/pdf","content-type":"unspecified","content-version":"vor","intended-application":"similarity-checking"}],"deposited":{"date-parts":[[2026,1,26]],"date-time":"2026-01-26T12:50:33Z","timestamp":1769431833000},"score":1,"resource":{"primary":{"URL":"https:\/\/www.mdpi.com\/1996-1944\/19\/3\/482"}},"subtitle":[],"short-title":[],"issued":{"date-parts":[[2026,1,25]]},"references-count":66,"journal-issue":{"issue":"3","published-online":{"date-parts":[[2026,2]]}},"alternative-id":["ma19030482"],"URL":"https:\/\/doi.org\/10.3390\/ma19030482","relation":{},"ISSN":["1996-1944"],"issn-type":[{"value":"1996-1944","type":"electronic"}],"subject":[],"published":{"date-parts":[[2026,1,25]]}}}