{"status":"ok","message-type":"work","message-version":"1.0.0","message":{"indexed":{"date-parts":[[2026,9,10]],"date-time":"2026-09-10T11:10:18Z","timestamp":1789038618851,"version":"build-2803163510"},"reference-count":42,"publisher":"MDPI AG","issue":"18","license":[{"start":{"date-parts":[[2026,9,10]],"date-time":"2026-09-10T00:00:00Z","timestamp":1788998400000},"content-version":"vor","delay-in-days":0,"URL":"https:\/\/creativecommons.org\/licenses\/by\/4.0\/"}],"funder":[{"name":"Deep Earth Probe and Mineral Resources Exploration-National Science and Technology Major Project","award":["2024ZD1003905"],"award-info":[{"award-number":["2024ZD1003905"]}]},{"award":["2024ZD1003905"],"award-info":[{"award-number":["2024ZD1003905"]}],"id":[{"id":"https:\/\/ror.org\/039b65w79","id-type":"ROR","asserted-by":"publisher"}]},{"name":"Key Research and Development Special Tasks of Xinjiang Province","award":["2022B01051-2"],"award-info":[{"award-number":["2022B01051-2"]}]}],"content-domain":{"domain":[],"crossmark-restriction":false},"short-container-title":["Materials"],"abstract":"<jats:p>To improve fly ash utilization in mine grouting materials and address the slow reaction and limited early-age strength of fly ash-based binders, a fly ash-based grout was prepared using fly ash and S95-grade ground granulated blast-furnace slag at a mass ratio of 70:30 and activated with NaOH-Na2SO4. A full-factorial experiment evaluated the effects of water-to-solid ratio, total activator dosage, and NaOH:Na2SO4 on fluidity, bleeding rate, stone formation rate, and compressive strength at 7 and 28 d. Representative 7 d specimens were characterized by SEM, EDS, and XRD. Increasing the water-to-solid ratio improved fluidity but increased the bleeding rate and reduced the stone formation rate and compressive strength. The preferred mixture had a water-to-solid ratio of 0.55, a total activator dosage of 5%, and NaOH:Na2SO4 = 2:1. It exhibited a fluidity of 195.0 mm, a bleeding rate of 1.70%, a stone formation rate of 99.50%, and compressive strengths of 8.5 MPa at 7 d and 11.3 MPa at 28 d. At NaOH:Na2SO4 = 2:1, the specimen showed a denser microstructure with fewer pores and cracks, a local Ca\/Si ratio of approximately 0.94, and more evident reaction-product features. The results provide an experimental basis for mix-proportion selection of fly ash-based grouting materials.<\/jats:p>","DOI":"10.3390\/ma19183854","type":"journal-article","created":{"date-parts":[[2026,9,10]],"date-time":"2026-09-10T10:27:21Z","timestamp":1789036041000},"page":"3854","update-policy":"https:\/\/doi.org\/10.3390\/mdpi_crossmark_policy","source":"Crossref","is-referenced-by-count":0,"title":["Mix-Proportion Evaluation and Microstructural Characteristics of NaOH-Na2SO4 Composite-Activated Fly Ash-Based Grouting Materials"],"prefix":"10.3390","volume":"19","author":[{"given":"Mengxin","family":"Xu","sequence":"first","affiliation":[{"name":"School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221116, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Feng","family":"Ju","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0002-5613-1822","authenticated-orcid":false,"given":"Meng","family":"Xiao","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Tengfei","family":"Wang","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"ORCID":"https:\/\/orcid.org\/0000-0001-6243-8284","authenticated-orcid":false,"given":"Dong","family":"Wang","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lidong","family":"Yin","sequence":"additional","affiliation":[{"name":"State Key Laboratory of Intelligent Construction and Healthy Operation and Maintenance of Deep Underground Engineering, China University of Mining and Technology, Xuzhou 221116, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Yingbo","family":"Wang","sequence":"additional","affiliation":[{"name":"School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221116, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Lu","family":"Si","sequence":"additional","affiliation":[{"name":"School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221116, China"}],"role":[{"vocabulary":"crossref","role":"author"}]},{"given":"Dongming","family":"Yang","sequence":"additional","affiliation":[{"name":"School of Mechanics and Civil Engineering, China University of Mining and Technology, Xuzhou 221116, China"}],"role":[{"vocabulary":"crossref","role":"author"}]}],"member":"1968","published-online":{"date-parts":[[2026,9,10]]},"reference":[{"key":"ref_1","first-page":"206","article-title":"Development of new polymer grouting material for mine and application of grouting reinforcement","volume":"42","author":"Zheng","year":"2023","journal-title":"Shaanxi Coal"},{"key":"ref_2","first-page":"282","article-title":"Current situation and development strategy of grouting material","volume":"50","author":"Jiang","year":"2022","journal-title":"New Chem. 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