{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,3,24]],"date-time":"2026-03-24T08:17:09Z","timestamp":1774340229210,"version":"3.50.1"},"reference-count":35,"publisher":"MDPI AG","issue":"6","license":[{"start":{"date-parts":[[2026,3,21]],"date-time":"2026-03-21T00:00:00Z","timestamp":1774051200000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China Project","doi-asserted-by":"crossref","award":["52568066"],"award-info":[{"award-number":["52568066"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"DOI":"10.13039\/501100001809","name":"National Natural Science Foundation of China Project","doi-asserted-by":"crossref","award":["42362033"],"award-info":[{"award-number":["42362033"]}],"id":[{"id":"10.13039\/501100001809","id-type":"DOI","asserted-by":"crossref"}]},{"name":"Gansu Province Industrial Support Program Project","award":["2023CYZC-34"],"award-info":[{"award-number":["2023CYZC-34"]}]},{"name":"Youth Doctoral Support Project of the Education Department of Gansu Province","award":["2024QB-053"],"award-info":[{"award-number":["2024QB-053"]}]},{"name":"Patent Transformation Guidance Fund Project of Lanzhou Jiaotong University","award":["ZH2023008"],"award-info":[{"award-number":["ZH2023008"]}]},{"name":"Gansu Provincial Department of Education: Outstanding Graduate Student \u201cInnovation Star\u201d Project","award":["2026CXZX-741"],"award-info":[{"award-number":["2026CXZX-741"]}]},{"name":"Special Project for Scientific and Technological Special Commissioners of Gansu Province Science and Technology Program","award":["25CXGA024"],"award-info":[{"award-number":["25CXGA024"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>To address the engineering problems of high cement content, high brittleness, and weak frost resistance of cement-improved loess in the seasonal frozen soil area of Northwest China, F1 ion curing agent (F1) and cement composite improved loess (FCIL) were used in this paper. Through unconfined compressive (UC) strength tests, consolidated undrained (CU) triaxial shear tests, and microscopic pore characteristics analysis, the mechanical properties, freeze\u2013thaw cycle deterioration law, and microscopic pore structure of FCIL were studied. The effects of cement content (Cc), F1 dosage (CF), number of freeze\u2013thaw cycles (NF-T), and confining pressure (\u03c33) on the strength, deformation behavior, and pore characteristics of FCIL were analyzed. The synergistic improvement mechanism of FCIL, as well as the freeze\u2013thaw damage mechanism, was elucidated. The results show that Cc is the primary factor controlling the strength of improved loess. The incorporation of F1 can further increase UCS and markedly enhance the failure strain (\u03b5f), thereby achieving simultaneous improvements in strength and ductility. An appropriate mix proportion was identified as CF = 0.2 L\/m3 and Cc = 6%. After 7 d curing, FCIL exhibited a UCS of 1.35 MPa, a cohesion (c) of 205 kPa, an internal friction angle (\u03c6) of 36.2\u00b0, and \u03b5f 1.8 times that of loess improved with Cc = 6% cement alone. CU triaxial shear tests indicate that, under all tested conditions, the stress\u2013strain responses of FCIL exhibit \u03c33-sensitive strain-softening behavior. As Cc and \u03c33 increase, triaxial peak strength (qmax) and secant modulus (E50) increase significantly. Compared with natural loess (NL), FCIL shows a markedly lower porosity (n), a substantial increase in the proportion of micropores, and reductions in medium and small pores. After multiple freeze\u2013thaw cycles, the evolution of the pore structure is effectively restrained. This indicates that the combined use of F1 and cement promotes the formation of a dense layered stacking structure, significantly improves the microscopic pore-size distribution, and enhances the mechanical performance of loess under freeze\u2013thaw environments.<\/jats:p>","DOI":"10.3390\/ma19061242","type":"journal-article","created":{"date-parts":[[2026,3,23]],"date-time":"2026-03-23T08:47:42Z","timestamp":1774255662000},"page":"1242","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Mechanical Properties and Freeze\u2013Thaw Cycling Degradation of Loess Improved with an Ionic Curing Agent and Cement Composite"],"prefix":"10.3390","volume":"19","author":[{"given":"Xingwei","family":"Wang","sequence":"first","affiliation":[{"name":"School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Jiandong","family":"Li","sequence":"additional","affiliation":[{"name":"School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Xu","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China"},{"name":"National and Local Joint Engineering Laboratory for Disaster Prevention and Control in Road and Bridge Engineering, Lanzhou 730070, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Baiwei","family":"Li","sequence":"additional","affiliation":[{"name":"School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"given":"Yanjie","family":"Zhang","sequence":"additional","affiliation":[{"name":"School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China"}],"role":[{"role":"author","vocabulary":"crossref"}]},{"ORCID":"https:\/\/orcid.org\/0009-0002-3465-9519","authenticated-orcid":false,"given":"Zhen","family":"Zuo","sequence":"additional","affiliation":[{"name":"School of Civil Engineering, Lanzhou Jiaotong University, Lanzhou 730070, China"}],"role":[{"role":"author","vocabulary":"crossref"}]}],"member":"1968","published-online":{"date-parts":[[2026,3,21]]},"reference":[{"key":"ref_1","doi-asserted-by":"crossref","first-page":"102947","DOI":"10.1016\/j.earscirev.2019.102947","article-title":"Loess genesis and worldwide distribution","volume":"201","author":"Li","year":"2020","journal-title":"Earth-Sci. 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